Back to Basics: Sandpaper Training


Andy Sewrey: Okay, so this is sanding training for Shearer Painting, we’re here at a job on Queen Anne, you guys have been in it for a little while here. We’re going to go through the basic types of sandpaper, the tools that we use, why we use them, we’ll mess around with them a little bit and get you familiar and go from there. This will be fairly quick, but for some guys this if the first time they’ve heard it, for some of you it’s a refresh, but it’s good to go through. So, starting with the papers, there’s the basic stuff, we’ve got the brown standard aluminum-oxide paper, you guys have all seen this. We use this in grits from 50-220 sometimes up to 320 grit. This is basically used for removing material we’re not going to do anything too fine with it. But it’s production paper we use it all the time. The green and this kind of streaked white stuff are either the open or free cut papers, these tend to be a little better if you’re sanding anything latex, they let go of material and they don’t clog up as much and the more you use it the more you’ll understand that. Again, they come in all the same grits, we’ll tend to use these again more when we have either latex stuff or a little bit more of a specialty situation. And then the black stuff, this is a silicon paper, this has a different backing, the previous two are on paper this is a water-resistant backing, so this is stuff we usually use only for wet-sanding, clear coats and that sort of thing. So if you really want to almost polish or finish before you put another coat on, you’ll use this with water. And then sanding sponges, and these have really become the standard so they’re easier to hold, they come basically in all the same grits, they’re really nice for working on profiles and we’ll do that in a minute just because they are flexible so that you can actually bend them into a surface or they’ll work in and you’ll still have a corner to work off of.

So for anything hand sanding, this is the stuff we use, and then also on power tools. The two basic power tools we use is just a standard Orbital–easy way is it’s the square one. This guy you can use any flat sheet paper on, you fold it in quarters and put it on here, we’ll do it in a minute. This again is for basically removing material; on super fine finish stuff we don’t use these that often. This is a random Orbit, it’s the round one, these are usually a hook-and-loop so they’re velcroed on– the paper is velcroed on the pad. You can get all different kinds of paper with these; there are 5 and 8 hole versions again more details that your site lead will take to you about if you’re actually using them.  The way that these guys orbit is that they leave less tracks in the material, if you’ve used these before and you see sometimes they leave little circles if you use that {standard Orbit} sander on raw wood in a stain-grade situation when you put the stain on it you’ll see all the little scratch marks. These ones still make the little circles but it spins at the same time and that has less pattern and less scarring on the wood. But for instance, what we’re doing here, this is all riff cut oak, this stuff we will hand sand and work directly with the grain and we’ll get into the difference of that in just a minute. So those are the basic tools, on the sides here we have the Festools and we’ll do a special training on these, they are very high-end vacuum assisted power sander, they are great for details and super fine finishes.

So, the uses; you use sandpaper to remove things, or just to remove material on an exterior, you’re usually using it to actually rip down or take paint off of something, you know when you’re using heavier grits like 50-80 grit to just mow it down. When you get into an interior, if you’re removing material it’s usually for the appearance on an exterior generally its more for removing failing material. Those are the two differences there. On interiors you’re going to use really from about 120 up, so they are much finer papers and on an exterior you might start at 50 and if you’re grinding you might even be all the way down to 16, and that’s’ on a different tool but that’s for actual restoration and big removal stuff. The other thing that you use them for other than removing is to provide tooth in the surface; if you have a super, super smooth surface that’s shiny, right, so if you get this guy {gesturing to a board} in the light it has and actual sheen to it. Paint’s not going to stick to it very well, if you think about when you’ve painted, if you’ve ever gotten paint a little bit on glass you know a razor blade will scratch it right off—if that glass was actually sanded and we’ll refer to this {the board} as a piece of glass, all those little bumps let the paint get in and hook you wouldn’t be able to get it back out of the glass. That’s why we’ll sand, you know, use sandpaper on shiny previously painted surfaces, so when you apply your primer, you apply your paint, it has something grab onto and hold. And that’s true on an exterior as well, but predominately on interiors. The other thing we use it for is something called Mill Glaze and that’s opening the surface up, so this is a raw piece of cedar that’s been plain but again, if you look at it in light, there’s a slight sheen. When this is made and there’s a plainer, the spinning blades that give this a nice smooth surface, the cells of the wood are basically like a sponge and when that blades hit it, it smashes them and makes them really tight. Again, if there’s a stain that’s going to this or even a primer, those cells are too tight to allow the primer or stain to penetrate and work properly. So, we’ll have to sand it to open those up, sometimes we’ll hit them with water first and then sand it, but the goal again of the sandpaper is to allow what we’re putting on there to get into it and bind and create something solid for the next coating to go on top of. Those are the basic reasons that we use it.

As far as techniques, this is where it gets pretty simple, we’ll move some stuff around here and play with it a little bit. The first thing we’ll start with is hand sanding, if you’re hand sanding, I call this “Big John” technique because the guy who taught it to me was named Big John and it was the first week that I worked for Shearer Painting in I believe in ’98. There’s a lot of different ways to fold up a piece of sandpaper, the goal of this is to make it useable and not waste it. So a lot of guys will just take a piece of paper, fold it in quarters like this and just start working with it. The problem is, when you put it on a surface it sheers, and it doesn’t really work. This is what you have to do to get your quarter sheets to go on a palm sander, but for hand-sanding it’s not that efficient, it’s big and lunky, you got stuff sticking off the sides, it might scratch glass or something you don’t want to sand.  The best way I’ve found to do this, and the way we really want you guys doing it, is you fold it in half lengthwise, usually take it back and forth a couple times so you get a decent tear. This is the important part if you go grit up, and then take it in thirds—you ever folded a letter to mail somebody, it’s the same thing. So what you have now is something that will actually fit in your hand and when you work it, it doesn’t sheer, so if I take this board and I’m actually mowing on it, it holds. If I do the same thing with this, it’s useless, it doesn’t work. So, the other side of this is you can fit this in your pocket, it’s not this huge thing that you keep dropping and you’ll lose it, it’ll actually go in your pocket and stay there all the time. If you use one surface, you flip it over and you got another one, and another one, and when you use all of those, you turn it inside out and you have three more. So you can use the whole sheet, you’re not mowing through sandpaper that you don’t need to and stopping and running down two floors to the tool pile to get it. It’s one of those silly little things, in 20 years of painting I’ve found to be probably the coolest thing I’ve learned. It’s silly, but it actually helps you out. The other thing that’s cool about it is you actually have a workable edge if you need to do some detail sanding it’s strong there’s a lot back there and you can do a lot of stuff with it. Sanding sponges are just pretty straightforward; again, these are nice because you get a nice even pressure, so if I push in the middle of this, the pressure is very even across the whole face. So if I go back to this piece of paper and I’m sanding on it, I’m basically—you can see where my fingerprints were—so I was basically sanding those four points. If I take this and put those same four fingers in it and sand, the whole surface is being used, so it’s more uniform. And then these guys are great when you’re on any sort of profiled stock, so if you have something that has a curve to it like this does, it will actually conform to the outside corners and you can get it in on inside corners and just do a good job all around. These are cool too, because this corner will compress, so if you have a really tight scoop that’ll mash in there and get your shape. That’s kind of the basics on technique.

Two things between paint grade and stain grade. Painted is paint grade, raw wood is stain grade. What we’re doing here is all stain grade, so you guys are hand sanding all this stuff, on paint grade stuff you have a lot more, it’s a looser deal, you don’t have to be as particular about your direction. So, that just means on this board, I could sand it in circles, I could sand it straight if I had a big chunk I could even go straight across it as long as I kind of finished it out this way. Because the small scratches and what not that I put in it when I prime it and then I paint it are going to fill up and they are going to be smooth and everything’s going to look good. I’ve given it a tooth so the primer can adhere and we’re good to go. On stain grade, it’s a totally different deal, being that the stain is going to go into the wood and show the differences and the different hardnesses and so on in the grain.  I’m sure you guys have seen houses where there was a deep gouge in the wood and you stained it and that gouge turned black or real dark. Same thing is going to happen when you sand that piece of wood so with stain grade you always want to go with the grain, so any of your scratches are following the grain lines. So if they’re a little deeper, a little lighter, it’s all just going to blend in and be good, if you sand across that grain it’s going to scratch it. Again on this, if you take it with it in a uniform way, and then you apply a finish to it, that’s fine, but if you come up to it and just start mowing on it sideways, even if you go back, you’ve created like a crosshatch in the grain and when you put stain on it that area will either show all those scratches or it may have just ripped the wood to a point where it’s cloudy or dark—so it’ll look blotchy when you stain it out. So here, with the work you guys are doing, it’s really important to remember that always work with the board, especially when you get down on like an inside corner down in here, don’t think it’s okay to get in there and start doing this like always work it in and out of the corners with the grains. Always. And if you can’t do it, go find your site lead, ask for instruction or a better way to do it, but don’t start sanding circles or side to side or anything like that. And from there, you move on to cleanup, you move on to application and so forth, but this is kind of unseen work, you know, there’s a lot of times especially with oil fnishes, if you don’t sand a surface well, they won’t level properly. Like that little bit of tooth allows the finish to kind of grab it and flow out properly and if it’s a shiny, really slick surface you actually get more brush strokes in it, so if you’re an apprentice starting to paint and you get really good sanding technique when we hand you a brush and start moving you into finer finishes, it’s just going to help that. We don’t want you to have to go back, and you might have the best brush technique in the world but if you didn’t sand it right the stuff isn’t going to flow properly, it’s not going to adhere properly, you might have a warranty issue down the road and so on. So that’s the basic of this guys, we’ll get into it and work with it more but thank you for coming.