The Perfect Finish Starts with Sanding

Jay June 23rd, 2022

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.

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

Jay June 23rd, 2022

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.

Susan Mercurio April 25th, 2020

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

- Customer Service April 29th, 2020
  
  Sorry, but we do not have any sources for this.
  
  -Paul
  Woodworkers Guild of America
  
james copeland April 1st, 2020

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

- Customer Service April 3rd, 2020
  
  Good afternoon,
  
  Here is what our expert had to say:
  
  No, there’s no downside to sanding beyond that. It’s just that there are diminishing returns for your sanding effort.
  
  Paul
  Woodworkers Guild of America
  
Carlos April 11th, 2017

Well presented. Thank you.