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3M Pads and Buffing

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Forum topic by Erik07 posted 04-30-2021 12:31 AM 316 views 0 times favorited 5 replies Add to Favorites Watch
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Erik07

14 posts in 85 days


04-30-2021 12:31 AM

Hey everyone, I have 2 items I’m hoping to get some clarity on which have left me somewhat confused. I think these are most relevant to finishes like odies, osmo, Rubio etc.

I frequently see mention of applying finishes with 3M pads. Generally, they’re being applied with grey or white pads. Why would you do this? Aren’t you basically just wet sanding by hand to a higher grit? Why not just sand to a higher grit in the first place?

The second is buffing off finishes. I believe I understand buffing a dry finish… you’re just polishing with a super fine grit I think. But why would you buff off the fresh finish, especially with an electric buffer? Is this different than just wiping it off with a towel?


5 replies so far

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Eeyore

111 posts in 297 days


#1 posted 04-30-2021 01:08 PM

The theory is that the particles you abrade from the surface with the pad go up into suspension in the wet finish, and then get rubbed down as filler into the scratches that the pad is making. The particles are the same size s the scratches, of course, so they make good filler. I even do it sometimes on the very first coat, where the particles are wood and I’m basically making wood filler that gets rubbed down into the tiny cracks and holes in the material to make a smoother, more solid surface for later coats.

Maybe this is just a superstition, but I’ve had good results with it so I will probably keep doing it. I’ve described this theory to professional woodworkers and had them look at me like I’m explaining a belief in ghosts, so I recognize there’s more belief here than science.

-- Elliott C. "Eeyore" Evans

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Erik07

14 posts in 85 days


#2 posted 05-01-2021 03:04 AM

Hmm I would think with non film building finishes, you would just wipe all those small particles off.

I’m glad I’m not the only one confused by it though. What about buffing off the finish once it’s soaked in? Is that just literally wiping it off with a tool or is there something else going on there?

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Axis39

482 posts in 678 days


#3 posted 05-01-2021 05:06 AM

It is a light form of grain filling if done on early coats. Although, what Eeyore says makes sense to me. (But, I’m no expert on those finishes, I’ve only just recently found them)

It’s ‘kinda’ like using pumice when french polishing. the pumice is rubbed on the surface and a slurry wiht a wet pad of shellac abrades the surface fibers, but, very, very finely. The slurry of pumice, wood fibers and shellac are pushed into the open pores, sealing and leveling the surface. It works better on tighter grain woods… Oak is tough. Maple almost doesn’t need anything.

I use an abrasive for my first coats with an BLO/Poly/Min Spirits finish for the same reasons. It works really nicely as the finish and wood fibers get a little sticky and you can force it down into the pores. If done well, and the last few swipes are cleaning off any excess, it can leave a glass-like surface.

-- John F. SoCal transplant, chewer uppper of good wood

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Rich

6833 posts in 1671 days


#4 posted 05-01-2021 05:33 AM

I can only speak for OSMO. When I was just starting out using it, I was searching for all of the information I could find on applying it. The 3M white pads came up frequently (I never saw reference to using grey pads, although I’m sure they’re out there).

The value that the white pad provides is its ability to hold the oil and distribute it. The white pads are virtually non-abrasive, but they are porous and hold a good amount of the finish and spread it evenly.

I tried the white pads and was unimpressed. They might be ideal for a countertop, but for finer applications their texture is too rough and leaves a rough finish.

My two go-to options for OSMO, depending on the circumstance, are foam brushes and cloths. I use the foam brush for application and the cloth for any touch-up that’s needed along the way.

If you’re using those bagged cotton t-shirt scraps, be sure to wash them. You’ll be amazed at how much lint they produce, and if you don’t wash them, it’ll wind up in your finish.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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OSU55

2794 posts in 3071 days


#5 posted 05-04-2021 12:49 PM

I think both your questions relate to the prepolymerized linseed oil finishes, like Osmo and Tried and True, that have gained popularity in the last couple of years. Never used them but the instructions for some of them mention what you are questioning.

With other finishes such as poly, danish oil, or sprayed lacquer or shellac, I dont do either. Pads dont fill pores, they pull wood dust out. Wet sanding to fill pores is done with sandpaper, and the resulting slurry is pressed in the pores with hands or a plastic spreader. I do quite a bit of this. Buffing these finishes is as you said.

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