Polyurethane/ oil combo. Can they live in peace?

[poppamango]

Just a quick question before I destroy my kitchen benchtop.

The top and bottom is coated in polyurethane. I have sanded the top/sides back to raw timber and was wondering if it's ok to coat the top with livos/ osmo/ hard burnishing oil or the like...but leave the bottom with the polyurethane untouched.
Will the top curl up like a propeller?

thanks for your advice
michael

[Master Splinter]

The moisture exchange rates of oil and poly are different, so it will be a risk.

[nrb]

To be safe IMHO I would stay with the same finish on both sides

[AngelaPetruzzi]

H
Curl up from what, do you mean moisture from the sink or otherwise??? You would really need to let the timber absorb quite a bit of water for it to curl up...then again, if you do, then better with oil as with e.g.Livos being vapour permeable, it will allow the moisture to diffuse and the timber to dry out.

If it is an old bench that you need to recoat due to wear and tear, then the timber should be stable enough.
The issue with poly is once the surface cracks and water seeps in under the coating, then this area will start to appear black, the coating often will start to flake and then...you can only sand to fix.

With the Livos oils, whilst they are not bomb proof, they will allow for easy repair or rejuvenation if or when need be, plus they are food safe.

Typically poly is rigid and oils aren’t.