Wet Sanding with Mineral Oil

[Dave Fritz]

Recently I've used mineral oil to do some wet sanding. I'm wondering how long I need to let that dry before adding another finish. Does it make a difference if it's an oil finish vs a coating finish like poly?

Would you recommend something other than mineral oil to wet the sandpaper?

Thanks for your help.

Dave Fritz

[Prashun Patel]

I would wipe off all that mineral oil with mineral spirits. Future sanding might be better done with mineral spirits or water with a drop of soap (the soap helps the water spread more evenly, IMHO).

Mineral oil is a suboptimal choice because it does not dry and makes it tricky to remove. Your goal with a lubricating agent is one that evaporates quickly or is easy to remove.

[Howard Acheson]

>>>> I'm wondering how long I need to let that dry

Mineral oil never dries so you will never be able to overcoat it with another finish.

I suggest you use a chemical paint stripper containing methylene chloride and remove all the finish you have applied. Then apply a couple of coats of a dewaxed shellac (Zinsser Sealcoat) to form a barrier over any residual mineral oil. Once the shellac has dried, you can apply whatever finish you like.

Be warned though, if you don't get all the prior finish removed, you will have problems down the road.

[Mike Henderson]

The only time I've used mineral oil is to rub out a finish with steel wool. Usually to knock down the shine on gloss lacquer.

I don't think I'd want to put it on raw wood and then try to put a finish over it.

Mike

[Scott Holmes]

If you are finishing a cutting board then you are OK. Otherwise it needs to be removed. Mineral oil is a fine lube for rubbing out a finish and the best finish with wax melted in for cutting boards any other application is not recommended.

[Dave Fritz]

Thanks so much. I've done what's been recommended and removed with mineral spirits and have given it one coat of shellac. I'll let that dry and give it one more coat just to be safe.

Is there less of a chance of problems with an oil finish or a poly finish.

Thanks so much, lesson learned.

[Scott Holmes]

Shellac will seal the wood. Oil (only) and oil/varnish blends are for raw wood; NOT sealed wood. To clarify Oil/wax or oil, varnish and MS (oil/varnish blends e.g. Danish oil) are "in-the-wood finishes. Varnish, shellac, lacquer and all the water-borne finishes are film forming finishes.

Poly is a type of varnish; oil-based but not an oil finish. Pure oil finishes are not very protective; regardless of what you may have heard or been told.

What is your project? What type of wood?

[Dave Fritz]

Walnut bowl.

[Alan Lightstone]

Outside of cutting boards (with wax as Scott said) I would never use it as a lubricant. I tried that once. Unbelievably messy, and was a pain to remove.

[Scott Holmes]

Using mineral oil as a lube for wet sanding is OK; it cuts much slower than MS or water. MS will clean it off pretty easily.
If your finish is thin mineral oil will help prevent sanding through; to a point, it can still happen.