WWGOA Editors

Finishing Part 1: The Perfect Finish Starts with Sanding

WWGOA Editors
Duration:   6  mins

Description

Jim Heavey from WOOD Magazine starts a three-step process for creating a perfect finish on your next woodworking project with tips on sanding. The first step is to understand the properties of different grades of sand paper and knowing when to use each. Jim takes you step-by-step through the sanding process.

Related Videos:
Part 2: Choosing and Using the Best Stain
Part 3: Applying a Top-Notch Top Coat

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4 Responses to “Finishing Part 1: The Perfect Finish Starts with Sanding”

  1. Jay

    That was a very good presentation. I prefer to use the 3M professional sandpapers. They are heavier paper with a waxed/coated backing. They do seem to last a lot longer. I do a fair amount of furniture refinishing. When using a power sander, the 3M paper will get hot and the wax coating tends to melt onto the rubber pad on the sander. Then, when changing the sandpaper, it can pull off pieces of the rubber. It is a disadvantage of that sandpaper, but you can buy replaceable rubber pads for power sanders. With sanding off old finishes, the finish can melt onto the sandpaper and it makes the sandpaper much less effective. The old finish can then harden and, in the power sander, that can produce swirls in the wood surface that are not always easy to remove. Sometimes you can scrape the deposits off the sandpaper with a putty knife or a paint can opener, but usually that means that you will need to discard the sandpaper even though it is not completely used up. When sanding anything veneered, be very, very careful. Do not use anything coarser than 220 or you can accidentally sand through the veneer, which is usually only paper-thin hardwood glued onto a wood-product substrate. If you do sand through the veneer (and I've done that too many times), all is not necessarily lost. You can use a gel stain, which if brushed before it dries (and it dries too quickly), can simulate the wood grain and hide the revealed substrate. Practice on some scrap first because the gel stain is difficult to remove once it has dried. When migrating to sandpapers with finer grits, depending on the wood, I often find that 80, 100, 150 and 220 are adequate and you can often even skip the 150. If you do a lot of woodworking, you might want to consider having a dedicated power sander for each grit that you usually use. I haven't seen 120 grit in the big box stores here. On the lathe, I'll do my last sanding using 400 grit, wet/dry sandpaper. When sanding end grain, it can be pretty hard on the sandpaper, even on a belt sander. One trick is to spray the end grain with water and then then immediately sand it while it is still moist. If your work piece required gluing together several pieces, the heat from sanding can effect the glue. I can sand a work piece "perfectly" smooth only to find the next day that I can feel and see the interfaces of the glued up sections, which requires re-sanding. Sanding beyond 220 when working with the softer hardwoods can be futile. All too often, the surfaces look great until the stain is applied, which accentuates all of the sanding marks. Sanding off sanding marks results in reduced wood thickness, which can affect form and function. If you use a water-based dye stain, like General Finishes Dye Stain, it will make the grain rise. Sanding beyond 220 before using that dye stain is futile because it will be very rough after applying the dye stain. After it dries (about 2 hours), it can be re-sanded with 220 or 400 and the dye stain can be applied again if needed. The oil stains don't have that issue. Perfection is rarely achievable. The hardest part of woodworking is applying the finish (drips, runs, bubbles, rough spots, missed areas, puddles, dust, bugs and other blemishes). Acceptable should be your usual goal. If you achieved more than that, you were probably just lucky. Sometimes it will look great until you examine it under different lighting. Sometimes the more you try to improve it, the worse it gets. There is a point when enough is enough. Enough.

  2. Susan Mercurio

    I can't find unfinished furniture anywhere any more, even online. Where can I get it? I'm in Minneapolis, Minnesota.

  3. james copeland

    on a normal flat surface will you stop at 220/240 grit. is there a reason to not go let's say to 320?

  4. Carlos

    Well presented. Thank you.

So maybe you've just finished constructing your project or you bought a chair like this unfinished, it's time not to put the finish on it, and that's where the little demons come out. Well, it's a relatively easy process if we take it in three steps and we're gonna show you how to do that. The first step is in prepping it where we'll talk about sanding, the second step is in putting a color on it like staining, and the third step is putting a top coat, and in this case we'll probably use polyurethane. We're gonna really increase the confidence level you'll have when you do a project like this after you've seen what we're gonna show you. And now let's show you step one. Now your preparation begins very basically with sandpaper, and maybe we should take just a minute or two to talk about sandpaper. You're gonna find when you start standing that you'd like to choose the correct grit. In this case, we're going to start with 120 grit a little bit more coarse than 240, and let me explain. When you see the numbers on here in this case 120, in this case 240 it talks about the grit size. 120 is a much more coarse grit than is 240. So we wanna start with 120 and start our sanding that way and work our way through maybe 150 than 180 to 220 or 240, so that's what you see on the first part. The second part is whether or not this is open or closed coat. Now in open coat it just means the grains are a little bit further apart allows the sawdust to fall out while you're sanding so that that sandpaper doesn't become clogged. And the last thing you may notice on the paper is weight. In this case, the paperweight A is a relatively flexible, smaller, thinner sheet, paperweight C is a little bit heavier, both of those are appropriate when you're doing sanding. Now, one more thing to add and we'll probably talk about this a little bit more during our finished section is papers that go up starting from about 400 to 1500 grit. And these, the grits as the numbers get bigger the grits get even finer, this will allow you to sand either between coats of finish or actually do a rub out on your final coat of finish. So now your choice is how you're gonna do your sanding, there's a couple of different options. The first is just to fold the sandpaper and use it by hand like you see here, the second is use a sand pad and on long broad surfaces and a lot of cases it's a good idea to use a pad, and there's a lot of different types, good idea to kind of look around see which ones fit your hands well. And the third way to do it especially on larger bigger projects maybe to use a power sander. And you see one here this a little pad sander, they work really well. The one option I would give you is this one is got a bag on the side of it which does a nice job collecting dust. But if I have the opportunity anytime I'll try and use a vacuum hose so this you can remove and put a vacuum hose on it, it's just a lot more efficient way to take the dust out. And lastly, if you're sensitive to sawdust and maybe even all the time it's a good idea to wear a dust mask like this, really helps keep the dust out of your lungs and it'll make the sanding a little bit more pleasurable. Now on this chair, the surface relatively smooth but on your project it may be a little bit rougher. In either case, it's nice to start out with 120 grit paper. So what we'll do is we'll start with 120 and go over this entire chair by sanding evenly in all these surfaces. And it's very important to make sure that all the surfaces are sanded to 120 before you move up in grits. Now, after you've finished sanding with 120 grit sandpaper, you're fairly comfortable you've sanded everything on the chair, it's time to switch to 150. Again, remember we're gonna work our way from 120 to 150 to 220 as we work up. After I'm done with my 120, a little bit of this 120 grit fairly coarse grit is still lying on the chair. Its important especially when using your hand and sandpaper like this to follow up that 120 grip with a vacuum hose attachment. And just vacuum that off a little bit, that way you don't have some of that bigger grit sitting on there so that when you start with your 150 grit sandpaper you're not rubbing that 120 grit, that one that was previously there back into the surface again, it really makes that job go easier and the chair gets smoother quicker. Now here's a tip for you. We're planning on ultimately putting some stain on this chair, and it's really important that the end grain and you'll see it here on the end of this chair as opposed to the side grain or maybe the top, the end grain is always more porous and it's gonna attract an awful lot of stain and really dark and the looks of this. So what I'll do is use finer sandpapers beyond the 220 to sand just that end grain. My thinking is if you have 220 here, do twice the grit. So go up to 320 and then finally 400 grit sandpaper and sand just the end grain. This additional sanding will reduce the porosity in here and make this edge look a lot more like the surface after stain has put on. And one more thing sandpaper does wear out every once in a while you're gonna have to break down and use a new piece of sandpaper, you'll be surprised how much faster this job will go if you'll just change it every once in a while. One last thing I wanna show you and that's cleaning up the chair in general. My favorite is to take the hose that comes with your vacuum or maybe even your shop vac and actually use that little brush on the end to vacuum up all the loose dust. It does a really nice job of taking the residual dust off the surface of that chair. For those of you that have one a blow gun on your compressor also does a very nice job removing the dust and does a remarkable job or moving dust especially on end grain. There are a couple of things that people will read about using either a tack rag like this or maybe mineral spirits on a rag. And I'd like to talk about two of those issues. Using mineral spirits on a rag I think works well between coats of finish, when you're using on raw wood I think all it does is make the wood wet. You will have to rewet it quite a bit and keep changing that pad to make sure that you're not just moving the dust around, I think vacuuming is a better bet. If you're going to a tack rag, make sure that the tack rag is used extremely likely almost as though you were just lightly passing over the top of this. The more pressure you put on this tack rag can take some of the chemicals that are in this rag the ones that you feel on your fingers when you're using it and actually transfer that to the surface of the wood. Those are not a good thing to have when you're trying to put a stain or finish on. So again my preference would be just use the vacuum attachment on either your vacuum or your shop vac and vacuum this off.
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