A waterproof finish on top of mineral oil?

[FrenchIan]

I've been making some end-grain chopping boards from walnut and ash, recently. I finish them with many coats of mineral (paraffin) oil, and they look OK. Out of some scraps, I also made some coasters/beermats, also finished with mineral oil.

Then I found out that's not proof against the wet bottoms of glasses - they left nasty rings. I've sanded out the marks, so I'm back where I was, but I would like a waterproof, wipe-clean finish.

What I normally use on wood is a home-made wiping varnish, a mixture of PU varnish, turpentine and linseed oil. This gives me a matt/silk finish, which I like. I'm wondering, though, how this would go with the current, oily wood?

Any help or ideas gratefully received.

Thanks

 

[cornucopia]

Hello- I sometimes use woodoc 5 or 10 (which is essentially a wipe on poly) over a previously oiled surface either Danish oil, mineral oil or lemon oil, I think you should be fine as long as the previously oiled surface is fully cured and you de-nib the surface before you apply the wipe on poly.

 

[FrenchIan]

Thanks for the advice, Cornucopia. You're spot-on.

Since nobody said it wouldn't work, I went ahead and tried it anyway. The first coat took a while to dry, after that it was business as usual.

I've since tested them extensively, with beer, wine and G&T - not all at the same time, though. No marks.

Cheers

 

[FrenchIan]

Well, the results aren't as rosy as I thought. I'm still getting rings on the surface. I think the first one I tested must have been the best.

What I suspect the problem is (but I could be wrong) is that as it's end-grain, it absorbs the varnish mixture too easily, leaving very little at the surface. So, when I sand it, it's all to easy to sand away the very thin layer of varnish, leaving the wood unsealed. Does that sound likely?

If that's the case, is there anything I can do other than (A) applying lots and lots of coats of varnish before/after I sand or (B) immerse the coasters in a bath of varnish for several days?

How about, eg, a cellulose sanding sealer as an "undercoat"?

All advice gratefully received

Cheers

 

[cornucopia]

I dont know about your homebrew but with woodoc- I tend to apply three coats- just lightly de-nibing between coats, this gives a very water resistant surface.

 

[FrenchIan]

I dont know about your homebrew but with woodoc- I tend to apply three coats- just lightly de-nibing between coats, this gives a very water resistant surface.

Thanks, cornucopia. I've just been to their website, and Woodoc 10 looks like what I need.

All I need to do, now, is get some to France.

Thanks for your help

Cheers