Paints and Coatings for External Timber Joinery - Session 1: Repairing and Preparing Joinery for Finishing

Alison: So, this is the first session that we're covering about paints and coatings for external joinery. So, my name's Alison Henry, and I'm Head of Building Conservation and the Technical Conservation Team at Historic England. And I'm very pleased to welcome my co-presenters. So, firstly, my partner, Domenico D’Alessandro.

Domenico: Hello. Hi, everyone. My name is Domenico D’Alessandro. I am Joint Head of Building Conservation with Alison, and I lead our Building Conservation Research Program.

Alison: Okay. Thanks, Domenico. And then, secondly, our guest speaker today, Vincent Reed.

Vincent: Hello, everybody. I'm Vincent Reid from Vincent Reed Ltd. I'm a consultant and conservator of historic joinery.

Alison: Brilliant. Thank you. So, just before we make a proper start, particularly as we've got so many new people who haven't been to technical Tuesdays before, big welcome to you. But I just wanted to let you know a little bit more about the technical conservation team. So, we're a group of technical specialists. We include conservators, scientists, engineers and various others. And we do research and develop guidance and advice on technical conservation issues. And there's a couple of links there. So, the first one that Matt has pasted into the chat for you, that takes you to the main technical advice page on our website, and that's where you can find all our technical guidance. And then that little brochure, the front cover image shown on the right there, all our published research reports and technical advice notes are all free to download, and they're all collated into that little catalogue. So, if you go to the web page there, the technical conservation guidance page, you can sign up there to our monthly newsletters in case you missed the opportunity that you had at the very beginning of the webinar. Every time- you'll see then when we produce any new guidance or any new advice. And you won't be inundated with emails. It really is just once a month. And it is only the technical conservation team's guidance. We don't cover wider HE News.

So anyway, moving on to today's topic, I mentioned a minute ago, this is the first of two webinars on paints and coatings for external joinery. And today we're really just focusing on repairing and preparing external timber joinery for repainting. So, we're not going to be covering major joinery repairs. That will be another webinar in itself. It's just those little repairs and bits of filling that might need to be done before repainting. And also, we're not going to say very much about different types of paint because that will be covered next week. So, we've got another webinar next Tuesday, and our guest speaker then is Peter Collins, who is a paint chemist. So, he's the right person for those sorts of questions.

But before we move on to Vincent's part of the presentation, we just wanted to let you know about a new research project that Historic England has started on paints and coatings. So, I'm going to hand over to Domenico now to tell you about that, and about how you can get involved. So, Domenico, over to you.

Domenico: Thank you. Thank you, Alison, and hello again, everyone. I'm just going to give you a very brief introduction about our research. I’m starting here showing you this painting by George Scharf, dating from 1829. It is showing you Allen's shop in St. Martin's Lane in London. As you can see, there are a house painter and his apprentice leaving with fresh supplies. They bring with them brushes, a jug of oil, a keg of white lead, and a paint pot of ground paste freshly prepared by Mr. Allen. You can see him grinding the pigment through the door. So, at the time of this painting, we are looking at the 1820s. There were a number of publications explaining how to use paint which was being supplied in a form that is recognizable today: cheap oil paints for essential purposes in a state ready to use. So, this was the rise of DIY, do it yourself. But painting is a complex art. Tools, workmanship, substrate and paint technology all play a part.

Nowadays it has become apparent that there is limited independent guidance available on the topic of paints and coatings, and many means have become current practice. Great attention is paid to the durability of the paint itself rather than the protection offered to the substrate. To address these concerns, we are undertaking research together with a range of partners and stakeholders. This is titled, as you can see here, understanding the properties and performance of historic paints and coatings, and identifying appropriate contemporary options for conservation.

The main aims of the research are to provide evidence-based advice, as well as a robust methodology for selection and specification of paints and coatings. At the same time, we would like to improve public perception of traditional external paint, increasing knowledge and developing capacity building projects to address availability of suitable paints and coating materials. And of course, skills.

Our areas of research broadly coincide with different types of substrate, So, we have external porous substrates and concrete, external timber, ferrous and non-ferrous metals, and we’re also looking at internal decoration.

We are posting relevant updates on our website in the Conservation Reserve section under materials and techniques. Matt has just posted the link in the chat. I would just like to highlight that we have an active call for case studies at the moment for inclusion in our research pilot starting soon. We will be focusing on timber, external lime plaster, and ferrous metal substrates, and you can take part by completing and submitting a short online form by the 26th of July. And more information is on our web page. Thank you.

Alison: Okay. Well, thank you very much, Domenico. So, now I'm going to hand over to Vincent. Vincent has come a long way since he was pictured here at the tender age of 16, just after he started his apprenticeship as an antique furniture restorer in the famous Brighton Lanes, and he spent the last 35 years working with historic woodwork. He's worked at many notable buildings, including Buckingham Palace, St Paul's Cathedral, the Tower of London, and King's College Chapel, as well as many much more modest privately-owned properties. Vincent now works with some of the UK's leading conservation architects and building firms providing conservation and restoration Advisory Service. And I'm absolutely delighted that he's with us today to present this webinar. So, Vincent, over to you.

Vincent: Thank you very much, Alison. Thank you for that introduction, and hello to everybody. Thanks very much for attending today's webinar. I am excited to share some of the knowledge and experience I have gained over my 35 years as a craftsman in the heritage buildings industry. Now, as Alison said, I began my career as an antique furniture restorer, but during my apprenticeship, I learned the importance of retaining original materials and conserving patina, which is the fundamental principles in our field. These principles have remained at the forefront of my mind as I transitioned into working with heritage joinery around 20 years ago. Now, to put this into perspective, imagine removing an original surface from an antique table using a belt sander. Now, such an idea would be shocking to most, but unfortunately, heritage joinery does not always receive the same level of consideration. So, today I aim to highlight the conservation and restoration practices I have used throughout my career and discuss how we can apply them to ensure preservation of our invaluable heritage joinery.

So, we're going to move onto the first slide. And why I produced this slide is, I wanted to really get people to grasp the importance of the difference between period joinery versus modern joinery. Now, understanding this difference is crucial. Recognizing why our historic joinery has stood the test of time provides valuable insights and aids in making informed decisions during conservation and restoration efforts. Now, this knowledge ensures that we respect and preserve the integrity of our heritage while applying appropriate techniques and materials. So, we're going to start with the left hand pane, or our period joinery first, and see what the difference is between the two.

So, we have slow-grown timber from colder climates. Back then they chose these incredibly hardy trees, and they can be identified by narrow growth rings. And this was due to these really harsh, cold conditions. Now, this not only produces the strongest trees, they actually- it gives strength and stability, which makes it an ideal choice when being used for joinery. Also, winter harvesting. Less sap during this time in the winter, meaning less sugar for wood-boring insects. Natural slow drying. Things were a lot slower then. And this causes less stress and potential structural failure. Timber selection. There was a much deeper knowledge of timber selection in the past. Specific sections of the tree were carefully chosen and optimised for the intended use, ensuring the highest quality of durability of the wood. We also have a dry joint construction. Glued joints in external joinery are actually a recent development. The glue was occasionally used for internal joinery such as staircases, but when using it externally, it creates a moisture trap which we'll see a little bit later on. And also, organic materials. Period properties are constructed from material sourced directly from nature. And most of these natural materials are both porous and flexible, which contributes to longevity and resilience of our historic structures.

The other thing people forget about are naturally-heated houses. The open fire was the sole source of heating imperial properties, and these houses had a higher relative humidity and moisture content, which meant that the joinery also had higher moisture levels when first installed, and this has enabled it to be closer to the external environmental conditions. So, if we go on the left, we can just see that the modern fast-grown timber from warmer climates, everything is rushed these days and thrown up.

Everything is harvested throughout the year, not just in winter. So you sometimes go to the timber merchant, you buy wood with insect holes already in them, and possibly some of them alive. Accelerated drying. We use huge, massive kilns. now. The trees are cut down and just thrown into these kilns, and obviously that's not going to do them a lot of good at all.

And also we don't select wood, certain component parts for joinery either. Back then we used to do a huge amount of that. Man-made or synthetic glues are introduced in modern joinery, which causes some problems, and also non-permeable materials such as fillers and resins. And also the big bugbear for our properties is the introduction of central heating, which started around 1880, which, again, has caused quite a lot of issues.

So I'm going to go onto the next slide now. Now, this is how modern materials can create and cause damage to our heritage joinery. So, let's start with resins and fillers. Now, this is often a quick and easy solution, but it's often used without proper understanding of potential risks. Now, the number of times I've assessed external painted joinery which on the first inspection looks okay, in quite good order, but once I've actually gone into a little bit more detail, it often reveals some really undetected damage below the surface. Now, the many modern fillers and resins, they're rigid, they’re non-flexible, they do not expand and contract like wood, which can cause problems. So, when these non-permeable materials are used as a replacement, it can have detrimental effects which will be demonstrated in our next slide.

So moving on to synthetic glues, these blues are predominantly designed to keep moisture out. But inevitably, when moisture finds a way behind this barrier, it cannot escape. So again, we'll be looking at the effects of this a little further into the presentation. Cementitious mortars, they are rigid with a low porosity. And modern paints. Some modern paints are so rigid, and they're vulnerable to cracking. They don't expand and contract. And just one minor surface crack on a modern layer of paint can lead to an awful lot of damage over time.

So, okay, now here's one of my favourite slides. So the 1960s saw a boom in synthetic materials such as paints and fillers and modified mortars. Now, in this slide, I want to take you through what I think has led to the replacement of this oak sill, which is circa 1825. This is original to the house, and it was just shy of its 200th birthday. But unfortunately, we didn't get the opportunity to sing Happy Birthday to it. Now, this most probably would have had a linseed oil based paint containing lead. Now, this combination was highly effective for the following reasons: the property of both linseed and lead are flexible, wickable, and lead also acted as a fungicide. So, this wonder combination of natural products has made a fantastic preserving agent, and is one of the reasons we still have a good example of external historic joinery in our heritage buildings today. Now, for the first 140 years of its life, this window would have received low maintenance with a change of paint colour from time to time. But let's ask ourselves, what has happened in the last 50 or 60 years that has caused so much damage, that replacement was required?

So, my interpretation of this is the following. The original paint was possibly removed to make room for this wonder paint, this new wonder paint that came in, that was a very quick-drying paint. So, very attractive. Now, after about 6 to 12 months, this very rigid paint has cracked. And there's these cracks that form on the surface. Now, then somebody comes along with a non-permeable, new, state-of-the-art filler, and this was used to fill the crack. Another coat was then applied of paint. Now we have two non permeable layers that trap moisture. Now the process has been repeated, but each time a certain amount of rotten wood is removed, just causing the crack to turn into a hole which gets wider and deeper due to trapped moisture. Now again, on first inspection, you could not tell the degree of damage. Actually, the lump of filler I removed, it was so large and below this was just wet compost with insects running around. Now bear in mind, this was mid-summer, and that particular summer we hadn't had rain for quite some time, which is- we have something like that now. But so this actually resulted in the replacement of the sill. So, this just gives you an indication what some synthetic man-made products can do to heritage joinery if it's not regularly maintained and looked at.

Domenico: Vincent, so, is some of the damage also because people no longer maintain traditional joinery properly?

Vincent: Yeah, I think there's a couple of things, Domenico. That is one case. We don't have regular maintenance checks on a property. There's not a record of, right, this was painted this particular date and this month, and it needs to be checked every 12 months, an inspection has to be carried out. So there is the lack of that. People seem to think that these paints and repairs are going to last for a good five years before we need to look at it. There's that reason. But there's another reason as well. And it is the non-permeable fillers that are used. Because on the surface it could easily look like this sill is in perfectly good working order. And the reason that this non-permeable filler is just rigid. It's like a big lump of plastic, so you can't see. So, therefore, if somebody's inspecting a window sill, for instance, unless you get a screwdriver or something that is quite invasive to have a good dig around, which you can't, you know, when you're surveying a property, you're going to sign it off as okay. It's only when you start really tapping and starting lifting things here and there, you understand the extent of the damage.

Domenico: Thank you, Vincent.

Vincent: My pleasure. Pleasure. So, here I am. And this is heartbreak. You can see the expression on my face here. That's not because I'm pushing the saw hard. That's because I'm just so upset that I've had to cut this sill out that lasted so long. But I'm removing it. You can see on the left-hand side the extent of the damage that this has caused. And it's just such a shame.

Alison: Okay, Vincent, thank you. That's really, really useful. And we tend to be aware, I think, of the harm that cement mortars have done to masonry. We don't tend to think, I don't think, so much about how modern materials can harm joinery as well. So, we're moving on now, and you're going to give some tips about repairing joinery before repainting.

Vincent: Thanks, Alison. Okay. So again, I want to talk about repairing joinery. And one of the biggest issues, I believe, is that the moisture readings are not checked in buildings and, you know, you have to take readings to existing joinery within the building. It’s absolutely essential. So, moisture and relative humidity readings have got to be carried out to the room and to existing joinery within the building. And this is to ensure that the introduction of timber for repairs is either the same or similar. Now, what happens is most wood which is purchased is kiln-dried and it's the moisture content ranges from 8 to 12%. This is suitable for internal work, but external joinery generally has a higher moisture content ranging from 12 to 18% and sometimes higher. Now, repaired patches can either expand or contract, causing differences in levels. And in worse cases — and I've seen this myself — they actually dislodge where the glue line delaminates and breaks. And also after a time the surface level between the join of your new piece of wood and your existing component part, there's a step formed. It swells, and so you have a step which is going up in your original joinery, or it will drop down. So, you'll see this visible, and that can be a big problem.

Alison: So can I just butt in there, Vincent? That's just a normal moisture meter, is it?

Vincent: Yeah, that's quite a good moisture meter. That's a Protimeter, which I'm going to show in a demo. But it's really small, and anybody that's surveying or looking after historic buildings really should have one of these, because it's very good. They're about £250, I think, Protimeter. And it gives you a really good indication of the levels of moisture. It won't read humidity, but it will read moisture levels in existing wood.

Alison: Presumably the requirement to test and match moisture content when you're replacing timber, that's something that should be included in a specification, would you say?

Vincent: Yeah, I do, actually, because you never see it. So anybody can just go and repair these buildings and use anything and it can cause problems in the future. So yeah, I would strongly recommend that that's included.

Alison: Yeah. Thank you.

Vincent: Okay, so this one of my favourite slides. This is an architrave. Okay. It's a bit of internal joinery, but it's an architrave from 1730. Now, have a look at this. These are two pieces of wood that have been joined together, and the joiner has matched the grain orientation from the piece on the top to the piece on the bottom. Now, why have they done this? Well, they had so much knowledge. They've done this because they knew that if they didn't get that right, those two pieces would delaminate, because with grain orientation, if it varies, it will expand and contract at different rates. So I don't even believe this has been pinned or nailed in. I think that's just animal glue. They stuck those two pieces together. But again, the lost art of selection is a real shame. But it's really, really important.

Now we go on to wood repairs. And I often get asked this, you know, how much of the original material should be removed? Well, obviously, we want to keep as much of the original material as possible. But you must consider the glueing surface area. It's got to be sufficient enough to ensure a strong repair. So there’s no point in just removing a small amount and then having a repair that's going to fall off in a couple of months or a couple of years' time. It's got to have enough surface area to ensure a good repair.

Now, how do we make good repairs? There are a couple of ways we can make good repairs. Always use angles. Never use butt joints. The angles give a good glueing surface, and also they're more desirable than joints. And also the other thing is to try to achieve a wood to wood repair. Now, what I mean by this is that a lot of people just rely on the glue too much. When I was an apprentice, we used to have to get chalk and rub each piece that we were trying to stick together. And if there are any highlights using this chalk, you get one side chalk the other side, rub it on to the other side. Is there any bits of chalk left on that surface, you had to chisel that off and tell you until the whole side was covered in chalk. And it was such an incredible surface. So a small amount of glue, a tiny amount of glue, can actually be incredibly strong. So again, it's just down to the craftsman.

Now, also, we have to look at strength. Is the repair going to be strong enough if it's put under stress? Now, if it's a moving part, such as doors or windows, it's got to be durable. So this must be taken into consideration. Now, also, what comes up, when to replace. You know, each case needs to be individually examined. But as a rule, I believe that if two thirds are non-repairable, then it may be time for a replacement. That’s what I normally say. And also, try not to hide these repairs. If a repair is good enough, it’s quite nice to see. This is mainly- we’re talking about varnish finishes now, but don't always try to hide the repairs. It’s part of the history of the building.

Now, on this particular slide, this is demonstrating. This is the bottom. It's the other way round, but this is the bottom of a sash window and it's where moisture has got in. It just rotted the lower part of the sash window. Now, here you can see that angle. I'm just going to go up to here and use my pointer.

There we go. So let's have a look at this angle here, this joint here. That's quite a steep angle. Now, the reason I put that street angle in there was a couple of things. I didn't want to remove any more original material. I want to retain as much of the original material as possible. But also I've got this section along here which is being glued and pinned into this fascia. Now I've got double, so it meant that I had the ability to put a much steeper angle. If I didn't have the fascia to pin to, then this angle would be almost past my hand. It would be a much longer angle. So more glueing surface and more strength. So again, it's just another way of having a look at how some repairs are made.

Now, here's one of my favourite examples. A client phoned us up and they said, please, can you come out and look at our [27:26 inaudible] window? We've had so many people, so many contractors coming out and they just want to completely replace it. And we were able to go to the site, examine, and actually take this window out, and save 70% of the original window. And the client was absolutely delighted. So this is another indication that if your repairs are good enough, and they're nice and strong, and you've got some lovely splice joints, you can retain original material. But it is, again, done on an individual basis. So, it's not always the case. But I think a lot of people just tend to think it's just too much trouble and let some replace it. So, here's another example here.

Now let's go into some non-wood repairs. We've talked about wood repairs, and let’s go to non-wood repairs. Now we have oakum on the left-hand side. This is a rope made of flax fibres which is drenched in either pine tar or linseed oil. And it makes a really good caulking method to seal joints. You sort of smash into these holes. But the good thing about it is, actually, it's wickable. Moisture will go in, but moisture is allowed to escape. So that's a possibility. Then you put a skim of lime putty over the top, but it is going to be a soft repair. That's one option. And then we move over to the right. This is a water-based filler. Now, this is going to be a general purpose filler. The good thing about these fillers is that they are porous. They will take moisture on, but also expel as well. And then much, much softer. And then, we go down to the two-part fillers and resins. Now, these are very, very hard resins, and they're non-permeable. Now, these can create a barrier that prevents moisture from escaping the wood. Now, if moisture is already present in the wood at the time of the repair, or enters through other means, it can become trapped beneath the filler. And this trapped moisture can lead to rot, mould growth within the wood, and exacerbates the damage rather than repairing it. So it can be very detrimental.

Alison: I just wanted to chip in there, because I never realised that you could use water-based fillers externally. I assumed because they were water sensitive that they were for internal use only. But of course, if it's protected by paint, then I can see that it would survive, wouldn't it?

Vincent: Yeah. And I think what it is is that all these modern synthetic materials that have been produced, the whole thing is about that water can't get through these. These are really, really hard and rigid. And so the problem is, people buy into that and they tend to use them, because they think it's the right thing to do. But what will happen is that… You know, you can use these. I've used internal polyphenols before for external joinery, but I would prefer that that repair would fail and be visible on inspection rather than a piece of car body filler that you couldn't see at all. So, I'm an advocate for that. So yeah. So yeah, yeah, absolutely. You can, and it is protected with a paint layer over the top as well.

Alison: Thank you.

Vincent: Pleasure. Right. So, when would we consider using non-wood repair? So, let's have a look at this image. This is a house from 1840, and the original front door. Now, this obviously is under cover. So, this door is never — unless there's a leak — never going to be exposed to external elements. Now, let's say, for instance, we had a repair around the hinges on this door. So, what we need to do is, we need to actually remove the door to cut a piece of wood in if we're going to do a wood repair. But let's say we get to the hinges, and they're rusted in, or the door furniture just is seized. And for you to have to remove it, you're going to damage your screws, you're going to damage your hinges. There may be a case then. Okay, well, look, this isn't going to receive any moisture, so why don't we use a resin or filler in this repair? Because the benefit about using these fillers is that you don't have to take as much of the original material away. So that's, you know, one of the ways we can look at using fillers, because this is not going to be exposed to the external elements.

Now, on this next slide, this is actually a project that we've been doing recently. This is an oak casement window. It has eight panes of glass in with profile glazing bars. Now, here on the left-hand side, I can get a small screwdriver, I can dig right the way down, ten millimeters into that wood. So what do I do here? Do I take the whole window apart and put a good, strong wood repair in there? The issue being with that is that I'm going to create quite a lot of damage, removing all the glazing bars, the other joints, re-drilling all the holes. So, I chose to put an epoxy resin consolidator in here. And this is an external face we're looking at, and I've just done the right-hand side, so the style rather than the bottom rail. Now, I preferred that option because it meant that I wasn't going to cause further damage. So there are times when you need to do this, but it's just, as I said before, on an individual basis.

Now what the problem is, is some of these glue joints. What happens is, in modern joinery, the joints are glued, and this is a modern window and that glue has trapped the water and it has rotted the windows from inside because it inhibits the drying. But also what I find is that, incorrectly, period joinery that hasn't had a jot of glue on it will also receive some glue when it's being repaired. And that's the issue because it's going to trap moisture. But also if somebody wanted to repair that in the future and dismantle that window, it's almost impossible to dismantle synthetic manmade glues. They're almost impossible. You can dissolve animal glues, but people don't use animal glues anymore. So it's another problem with glue joints. You don't need it if your joint is good enough.

Now, why do dry joints work? This is circa 1830, this image here. Now, this is partially an external bit of joinery. It was under a portico with some panelling in a Victorian mansion, so it did get a bit of moisture where it was. Now this has just been created using a mortise tenon, and it’s a draw tenon. So that hole in the middle holds a peg. But the hole between the tenon and the outer casing in the mortise is slightly misaligned. So, as you drive the peg through, it pinches that joint up to the shoulder. And that's how it is fixed. And as you can see here, it's absolutely perfect. It's in perfect condition. And then what we do here is do exactly the same thing. We have to slightly widen the hole of the dell to produce another draw tendon or you fill that hole up and then produce another draw tenon to the side of it. So this is what it does. It allows water to escape, and it just avoids any wet conditions that can cause fungi thriving and which will eventually lead to rot. Now, if that had been glued, we wouldn't be looking at that tenon now. That would be long gone. So again, another thing to consider.

Alison: That was absolutely great. Now this is the pioneering move in technical Tuesday. This is the first time we've done this sort of live demo. So, we're now joining Vincent there in his workshop. And we'd be very interested to hear your feedback about whether this sort of live demo works in our webinars, and whether you find this a bit more stimulating than simply looking at PowerPoint slides. But anyway, off you go, Vincent.

Vincent: Okay. Nice to meet you, everybody. It’s a bit strange to me because I’m staring at just a blank screen. So, I'm presuming you're there, but… Nice to meet you. That's good. Welcome to my workshop. It's a bit difficult, as Alison said, this is the first time we're doing this, but it's quite difficult because I can’t move around too much. But I thought it would be nice for you to see me in my working environment.

So, let's have a look at some fillers and resins to start with. So here I've got three types of filler. Let's put that to the side. Now here we have our two-part filler. This is a two part filler and it's exactly the same as car body filler. So, if I tap that, we all hear how rock-hard that is. It's basically like a lump of plastic going into your repair. On this side, I'm not going to do the same here, because this is a resin, and that hasn't actually gone off because it was a little bit old. But that would go equally- not quite as hard as this, but it will get pretty hard. The difference between these two is that this is very, very difficult to chisel carve. This is much easier. This almost behaves like wood. So this is why it's quite a popular option for joiners and carpenters, because they can fill their holes and they come along with a chisel profile plain or something like that, and they can actually mould that in. So it's a great material, but it's just, again, beware where this stuff is being put. Now, here I've got some hard- this is poly filler. Now, if I'm going to try and snap this look, it just literally breaks off in my hand. If I tried that with the two-part fillers, it's impossible. Absolutely impossible. So this is still hard enough to put in holes if you need to. But the good thing is that water is going to escape once it gets in. So, there are two fillers.

Can we see that okay, Alison? Is that all going well so far?

Alison: It's looking good and we're getting lots of positive comments in the chat. Thank you for your comments.

Vincent: Okay. So we touched upon a moisture meter. Now, this is a Protimeter. Now this is the moisture which is about £250. This is what I use. I've also got a slightly bigger swankier version. But it's really the case of…. Oh, actually, hold on for 2 seconds. I want to just show you, before we go on to the moisture readings, I'm going to put this up to the camera. And here, this is the same type of window sill that you saw in the picture that had to be replaced. This is another one that's had to be replaced, but in here is the car filler. So, I'm going to see… This has not been rehearsed, by the way. I’m gonna see what happens when we take this out. And there it is. It's on the top. And underneath here, it's just going to be rotten. And that’s going to travel all the way through here. So what's happening is that it looks okay. If that was all like that, you think, okay, that's fine. But it's not. It’s car filler. And it will go underneath. And this is all of our rot here. You can see it. It's almost like soil. Okay, so that's what you find. This is what you can't do on surveys, obviously, something like that. So I wanted to show you that. Right.

Let's go back to the moisture meter. I've got two extremes here, but let's take this very, very wet, rotten piece of wood. Now, here's my moisture meter. It's currently on A, which is the setting for this type of wood. And all you do is stick it into the wood. Now that's actually showing- You probably can't see that, but that's actually showing 100%. Now, let's go to the face here. I put it in and here we go. That's showing 14.3. So actually on the face, it's quite dry. So again, another tip here is that you can put your moisture meter on the surface of something. It's showing 14.3, which is absolutely correct for something like this. But we're 100% underneath because of these fillers. So let's take a new piece of wood. This is going to be about… Oh, live demos. I think Ainsley Hariott is going to come out in a minute and start cooking. Feels like that. So, this is 14, you see. So these two pieces of pine could actually be married together. So that's a little demo on moisture readings.

Now we’re going to go into glues. We have a traditional glue, which is here. This is hot animal glue. This is what was traditionally used. But as I said, it wasn't used on internal joinery. But you can see thi, you have to use this hot and gloopy stuff. I love the smell of this. Most people hate the smell of this. It is from animal skin and bone. So it's not really that nice. But there we go. Then we have things like, you know, your common PVA glue because this is your normal wood white glue and then you can get tougher. But a tight bond, that's tough for PVA then. This is the stuff that's been used a huge amount. Don't worry about the name. So this is a polyurethane glue. Now, this is the glue that people love to use because it fills gaps with lots of foam here. When you see this expanding glue, that's what it is. But it's not tried and tested. I don't like it. And also is just used too often for carrying out repairs. So that's a little section of the wood, the glue that you can use.

Now here, I know this is a chair, obviously it is not external joinery, but it is the same principle that I will show you here. Now, how much wood did I remove here? If you see on this side, this knee, it was completely broken. It was exactly the same on this side. So I had to decide how much of this material I wanted to use. And basically, I removed this much material you see here. That's the broken knee. And look at this very, very steep angle. So I cut that out, and it had to be nice and long for my glue to have a knot surface. And then here we have it. This is the joint from here to here. Now, this is a really, really good joint. It's incredibly strong. If I grab this leg alone and probably smacked it on the bench, it probably wouldn't break here. It will break here. This is just glued using a block plane and animal glue, and that's it. But it takes a long, long time to do something like that. But that's an example of a really, really good wood repair. So that's it. Back to you, Alison.

Alison: Okay. Well, that was brilliant. So somebody commented, you need twice the time. So, yeah, we could have spent a lot longer on that. But that gave you a flavour of the sort of work you're doing, some of those materials, which I think will address some of the questions in the chat as well. So anyway, now back to PowerPoints, and we're going to look at some preparation of joinery before painting.

Vincent: Matt, can I just have a quick gauge of the time before I just start?

Matt: Yeah, we've got 10 to 2. So I know we are going to run slightly over time. So what we'll do, we’ll keep on. The Q&A session will probably run beyond 2:00. Those of you who have to leave for other commitments, we do apologise. But this is being recorded, and the Q&A session will be on the recording. So, maybe that's your option, to view the Q&A in the recording. Back to you, Vincent.

Vincent: Great. I'll try and speed up a tad. So let's have a think about what the sanding does to the surface of wood or any type of surface. Now, when wooden surfaces are sanded, we have to understand that wood fibres are damaged. This results in a rough, open, porous surface. So, let's imagine taking a section of rope and repeatedly cutting it lengthwise around its circumference with a Stanley knife or scalpel. This would split all the fibres, causing the rope to expand in size. Now a similar effect occurs when you sand wood fibres. Fibres become significantly more absorbent and the contact with any liquid, such as paint or varnish, causes them to expand. And this leads to a rough surface rather than a smooth one. So we've all sort of felt that rough surface, and that’s either down to a bad environment for dust or it's the grain that's been damaged and then raised as liquids hold onto it.

When do we use sandpaper? Well, we use sandpaper to make a surface smoother. By that we go through the grades, and go right through the grades from the roughest to the smoothest. And we can also use that for adhesion as well.

On the next slide, when we come across our surface for painting, it is really important to assess what's going on. Now, are there any potential historic layers below this? All too commonly this just gets removed and it just gets disregarded. So could there be this magic combo of linseed and lead? Don't remove this, but just maybe try to remove the top modern layer. We do this by dry scraping and cleaning with a detergent, which I'll show in the next demo. And there's also no need to go over the top with coarse grades. That's another thing to bear in mind. If you're preparing printed surfaces, don't always go out, as I say to those coarse grade papers excessively. And if you're sanding bare woods, it may already be smoother than what you actually end up with a few used coarse papers. So again, just something else to really bear in mind. So yeah, that's that on the sandpaper.

Domenico: Vincent, could you say something here about the techniques you would use for preparation if you suspect that you're dealing with all the lead paint? So, an absorbent material.

Vincent: Okay. Yeah, good, good question. So this has to be incredibly considered because obviously lead has such a toxic- it’s very toxic. So yeah, what I find good is obviously having the correct PPE is absolutely vital. But also to use something like a plant sprayer and water and use an abrasive, and that will keep down all the dust. Wet flatting is another way you can go, but it is basically anything that will avoid those particles being airborne. That's something you have to definitely consider.

Domenico: Thank you.

Vincent: So, on this slide, this is an example of a well-prepared surface and not such a well-prepared surface. Now, time and time again, I hear people saying, oh, the paint has failed, the paint is rubbish. It's absolutely clear it's failed. But a lot of the time it’s in preparation. Preparation is 90% of the work and then 10% goes into finishing. It’s all about the prep. On the left-hand side, we have somebody who's rushed and not prepared properly. On the right hand side, somebody who's really thorough, but all the scratches and the surface is now ready to take another coat. Now, it only takes one small amount of paint to be popped in one of those areas on the left-hand side that has absolutely no scratches at all, and then that paint can flake. So again, that's another thing, it's doing the preparation.

Now, when we look at new surface versus old surface, we have to be mindful, obviously, of historic layers. We have to really be mindful of patina and undulation, which gives that lovely historic woodwork its identity. You know, I prefer to use what's already there and I build on top of that. However, there are some considerations. If there's a modern paint on top of a linseed paint, then I would look to try and remove that molten paint by the use of a heat gun or some dry scraping, or if the original linseed and lead paint has been removed and replaced with a modern paint, that's another reason why you may want to go back to bare wood. So, those are the two considerations.

When we come onto adhesion. Again, we don't need to sand right the way back to the wood. In most cases it's unnecessary to strip it right way back to the wood. Now, why is this the case? When you're doing that, you're removing these amazing base coats, and it will leave an open grain appearance.

It could have this wonder lead and linseed and, you know, if you remove this, it gives less protection. So manufacturers will always say on the tin to remove back to bare wood but it's not always the case. I try to avoid it wherever possible. Can you recoat using different paint types? So ideally it's best practice to try and use the same paint when applying over an existing surface. However, if correct preparation is carried out, you can achieve this. I've done this before. It’s tried and tested. Applying to existing layers. It's all down to the prep and cleaning. It's absolutely key. And I think if this protection is protecting and conserving our wood, let's try not to remove these finishes. As long as there are no moisture traps there. Base coats, again, grain fillers and base coats are so important to keep. And it's a great base coat to build on top.

And here, just a quick example of a window. And you can see here, this is lovely paint undulation. It's telling me that it's a historic window. Do I want to really burn all that off and get back to a short profile? I personally don't. But if I was to lose some of this profile, it would just be coming round rather than this indent there. Then possibly we'd have to consider burning back to bare wood, or maybe dry scraping and sanding, but we have to be careful, again using a wet flat technique if it's lead, which it almost certainly will be.

Alison: Yep. I was just going to say while we switched over, I really wish I had known about this 20 years ago, because I stripped all my external joinery back to bare wood thinking that that was going to be the best, give the paint the best adhesions. So I really wish I'd known then what I've learned today. So, anyway, cracking on with the demo.

Vincent: So, now I just want to take you through some of the abrasives that we use. We have all sorts really. I can’t go through all of them, but we have things like wire wools. This tends not to get used in external joinery because it just doesn't. I don't know why. This is probably my restoration background that I use. Wire wools. Fine, 4.0, and number four. This is the very coarse, that's the very fine. One of the things I absolutely love and use a lot is something called [52:41 inaudible], which is sort of like a scotch-brite pad. And this is really, really, really good for rubbing down many sorts of painted and varnished surfaces. You can use it on bare wood, but this is really, really good. And you can wring this out and get it into the nooks and crannies.

Another thing, this is a sponge-back sandpaper. This is really, really flexible, and you can screw it all up, and you can pick it up and you can get into all the little pores, nooks and crannies. That's a sponge-back sandpaper. And then we move on to grades or coarse grade sandpaper. Now, the lower the number, the coarser it is. And this is a 40 grit sandpaper, which is pretty much one of the courses that you can get. And then this is a 120, for instance, but it goes right the way down. And we would probably go as far as a 320 grit. So this is incredibly smooth, and gives a lovely, lovely finish. So, that's some of the abrasives that you can use.

Now what I want to show, I've got an amazing door here. This door is probably around circa 1600-1640. And it's pit sawn. I don’t know if you can see these beautiful pit saw marks, but it's a lovely, lovely door. Now, it’s an external door, it has a modern paint on. So, how are we going to do this? We're not going to sand this with a big belt sander or an orbit sander. We're just going to lightly clean the surface.

Now, I would prefer, rather than use 40 grit sandpaper, I would prefer to use even a fine wire wool to keep the surface back. And what am I going to use? Very expensive water and detergent in a squeezy bottle. And then all I'm going to do it just spray the surface, use my wire wool or we could use the [54:34 inaudible], and I'm just going to work methodically in almost six-inch squares, and I'm going to cover with a flat hand, and make that… That's all I need to do. No sandpaper required. I now feel like a market trader. And that's it. So, I could use that or I could use the, [55:01 inaudible]. So that's the way we can resurface, and that is perfect. You see how quick that six-inch square there, how quick that took. Now, I'm always saying, absolutely takes time or preparation, but you can see here, if I used 40 grit sandpaper that would have missed so much of this undulating surface. When the paint is applied on top, that will start to fail.

That's what we have there. And with these abrasives, you know, it all depends, again, who has them in their hands. It's just really, really important to understand that. And this is something that is used an awful lot, which is the orbital sander and the detail sander. Again, it can be unnecessary, but a lot of people actually don't want to use their hands to prepare surfaces. So that was just a very quick demo of how to clean that surface back, and to go through some of the abrasives. So, back to you, Alison.

Alison: Fantastic. So, thank you. That was really great. I am conscious that we're up against it and I know there was another slide to come where you were going to talk briefly about applying paint, but I think it's clear that there is a demand for a little bit more on this. So I wondered whether we might perhaps actually just skip that slide, if that's okay with you. And we'll focus on that. Because really the focus of today was about prep. So, we'll skip that and we've just got a few summary points there, the sort of key takeaways there for you. But if we've got a few minutes for people who are happy to stay on for a bit longer, then we will look at some of the questions that have come into the chat. So, Matt, do you want to bring those questions up for us, please? I mean, I know, Domenico, you've got one that you wanted to raise. And actually someone also raised this in the chat. So, if we start with my next question, that will also hit one of the ones that was in the chats.

Matt: So we have the Q&A there. And please, I'll invite Vincent and Alison to please turn on your webcams. Here we go. So we can put a face to the name. That's fantastic. Thank you.

Domenico: Thank you. To kick off, we also had this question in the chat. Vincent, you showed us your Protimeter earlier. Would you say something about calibration, and also something about how salt might affect readings?

Vincent: Yeah. Okay. Yes. So, this particular Protimeter, it's quite handy actually because there are different letters along the bottom, and you have to choose your letter for your certain species of wood. Now, fortunately the first letter, we have ABCD, first one is A. With that we would measure pine and oak. So what's good is the majority of external joinery is either going to be pine or oak. Sometimes you'll have mahogany, but it's unusual. So that's quite good. So you can just keep on A. You do have to, from time to time, calibrate these, and you can just look at that in an instruction manual to set up the calibration. But it's not often that you have to do that. And then, regarding salt, I've never really had a lot of interference with salts because it's always had a painted surface or a varnish surface over the top when I've been taking moisture meter readings. However, I have taken moisture meter readings on exposed timber in barns and timber frame buildings, and they can, you know, you can get salts on the surface which will actually make a difference on your reading. But I've never come across that. This has always been a really trusty friend for me. I hope that answers your question.

Domenico: Yes. Thank you.

Alison: Okay. So turning to-a lot of questions. Not surprised. It's a really interesting topic, and everyone has done their own painting probably, so, you know, this really feels relevant. But a lot of queries then about the different types of fillers. Now, people are saying, can you mention brands? Well, I don't think we really can. But one of the questions was about internal or external. Well, Poly filler, okay, that's brand. Water-based filler. I mean, is there a difference in your opinion between something that's marketed as internal, something that's marketed as external in those sorts of fillers?

Vincent: Yeah. No, sorry, sorry. The difference between the two is that one is slightly harder than the other, and they use different sorts of polymers and binders. I think with the external water-based fillers, they add gypsum as well. So, it's just a bit tougher, that's all. So probably go with an exterior filler. But the main point is, it's going to absorb moisture. Even though it is quite tough, it's going to absorb moisture. So, yeah. But like I said before, it's better to have that being visibly, it’s failed because somebody put water-based filler on rather than a two-part car filler.

Alison: Yeah. Okay. There's another question about whether the prep and the filler are the same for a coastal location. And I guess that also would apply to any other very, very exposed area.

Vincent: Yeah, it's going to be the same. But again, it's just it's going to be very, very exposed. Then the maintenance checks would just have to be a little bit more regular. That's what I would say.

Alison: Okay, so down to maintenance. There was also a question about end grain and about sealing the end grain with- someone's asked about sealing it with a resin repair. And then I think there was one later on about sealing the end grain, presumably with something like your sort of epoxy sealant. So what's your view on end grain?

Vincent: Well, my view on end grain, sealing end grain, is that that's where the moisture is going to escape. So, you think of it like a bunch of straws. You know, that's where it's going to escape. So if you seal that it has to find another route and then it could get trapped. So there's no need to. But the other thing is it's in the summary. Wood can get wet for a short period of time as long as it can dry out. Look at these guideposts you see in the countryside. They’ve been there for tens and tens of years. They're still standing. So, you know, we don't need to protect it as much as people think.

Alison: Yeah. So it's remembering the end grain. It's two streets, isn't it? It can get more moisture up but it can lose it through that way. Yeah. Okay. There's quite a few questions about paint removal. We won't cover those. That will come in another webinar that we're planning for the autumn. There were one or two questions about the window care system, or it might be called repair care now. So, this is a sort of very flexible filler. But I think I think you probably did… Oh, yeah. Okay. So I think you should probably cover that because it's not, I mean, flexibility obviously is one quality, but it's still got that issue that it won't let water through it. Would you just want to comment further on that?

Vincent: Yeah. So that's these products on the one on your right or your left, I'm not sure what it might be. So this is still- it’s basically like a rubber, but a plastic stroke rubber. So, yes, it is flexible, but it will not allow moisture out at all.

Alison: No. Okay. Okay. There's questions about whether there is linseed paint below the modern paints. And someone in the chat said get paint analysis. But are there any other ways that you can do that? And testing for lead is another issue.

Vincent: It’s… It's a bit difficult. If I were to remove some paint layers, I can tell you exactly if it was lead without even… It's just got a different look and feel. it’s denser. It's… It doesn't have any sort of cracking. And also, if you… Not saying you want to do this, but once it’s starting to be removed, you can smell it. You can smell lead… If it smells of linseed oil, then it's almost certainly- and it's a good 150 years old, there’s a high chance it's going to be lead.

Alison: With the assumption that if it's more than, say, sort of 50 years old, it's likely to be lead paint anyway.

Vincent: Probably. It is, yeah. It's a controlled rating.

Alison: There was another question about what glues were best, but again, I think you've probably covered that, and it's not some- my reading is that it's not so much the type of glue you use as where you use the glue and how much you use it or.

Vincent: Yeah, exactly. So, just on that point, if I was going to glue two pieces of wood together, what would I use? I would use something like- I can't mention the name, but it's the PVA that is a yellow colour. It's a very, very strong type of PVA. You have two types of PVA. One is white, which is in here, and one is yellow, which is in here. So I would use that. That's really, really, really good glue. The polyurethane foam glue, I don't think it's as good, because there's lots of air bubbles in it, so I don't think it's going to be such a good surface, glueing two pieces together.

Alison: Okay. Well, we've gone 10 minutes over. I mean, I see there are a few questions there about accoya. I think it's probably clear we also need to do a webinar about joinery repair generally. I think that might be another topic. So, we'll get Vincent back. And then there's some questions specifically about paint, but those we can cover with Peter next week.

So, we will see if he'll mention things like zinc oxide and titanium dioxide. So, I think we've… I think some of the questions that came in, the answers were probably then revealed later on. So, I hope we have covered most of the questions there. But I think we've gone 10 minutes over and we probably ought to call it a day.

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