varnish or poly on top of mineral oil?

[Rich Engelhardt]

I stuck a butcher block top on the roll around kitchen cart I made for my wife.
I decided to make it a "working top" by treating it with mineral oil.

I got to wondering about maybe some time in the future if I decided to switch it to a "non-working" top and give it a film finish of some kind, what other than a good sanding, multiple wipe downs with mineral spirits and a coat or two of Seal Coat I'd need to get it ready for varnish or poly?

[Jim Becker]

The issue is that mineral oil is a "non drying" oil. If any of it is left on the surface or near the surface, when you go to coat with the film finish, you may have adherence problems. Mineral oil does dissipate over time in my experience, but personally, I'd try the shellac as a barrier coat if you ever want to do this. Of course, I'd just keep it as a "working" top forever!

[Steve Schoene]

Yes, mineral oil is non-drying, but it is soluble in mineral spirits. I'd use a particularly light mineal spirit, naphtha, to remove the mineral oil. Use it copiously, wiping off the naphtha with a many paper towels. After doing this you can let the wood dry and seal with the dewaxed shellac before applying a film finish.

[Prashun Patel]

I think you'll be fine with what your planning.

[Howard Acheson]

If the butcher block top has been used for food preparation, you will have some animal fats that have soaked into the wood. Depending on how the surface has been cleaned in the past, you may have some adhesion problems. I would probably use a chemical paint remover containing methylene chloride. Get one that is water rinseable.

[Rich Engelhardt]

Thanks all!
I'll probably leave the top as is with the mineral oil finish.
It looks real good as is and I'd rather not put any more time and/or effort into the top.

[Prashun Patel]

The easiest solution is to just mix a little of any oilbased varnish (poly or otherwise) into an oil like Boiled linseed or tung (oils that dry) and use that. You'd apply it like the mineral oil: flood on, wipe it all off. Enough varnish will impregnate to give a little more protection vs the mineral oil, and it won't leave marks if you leave it on top of something (as mineral oil can do).

[Kent A Bathurst]

Thanks all!
I'll probably leave the top as is with the mineral oil finish.
It looks real good as is and I'd rather not put any more time and/or effort into the top.

Bingo. Leave it alone.

If it goes out of service, sand to clean up the top, then refresh mineral oil. Or - do that to refresh the surface after a few years of getting chopped on.