# polyurethane on oiled butcher block table



## BenKangas (Mar 27, 2012)

I have installed a new maple butcher block as a bar table in my kitchen. It will not be used for food preparation. I have applied several coats of mineral oil to seal it but I would like to make it more impervious to food and drink spills. I'm about to apply oil-based polyurethane. Will this work given the previous mineral oil treatment? Other than making sure there is no excess mineral oil on the surface are there other preparatory steps I should take?


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## chemmy (Dec 13, 2011)

BenKangas said:


> I have installed a new maple butcher block as a bar table in my kitchen. It will not be used for food preparation. I have applied several coats of mineral oil to seal it but I would like to make it more impervious to food and drink spills. I'm about to apply oil-based polyurethane. Will this work given the previous mineral oil treatment? Other than making sure there is no excess mineral oil on the surface are there other preparatory steps I should take?


For sure you will have to remove the "excess" mineral oil -- and more - wipe down with alcohol several times to get as much out as possible!!

Mineral oil is a "non" drying oil, unlike tung or linseed, etc.. after you've gotten all up and out that you can, let dry thuroughly, then seal with zinnser sealcoat shellac 1 coat only, then when dry, sand 320 and then you can apply your poly ok?


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## BenKangas (Mar 27, 2012)

I presume isopropanol will do for mineral oil removal? However....the label on the "Bona Woodline" brand "oil-modified" polyurethane I bought says "not recommended over shellac".


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## chemmy (Dec 13, 2011)

BenKangas said:


> I presume isopropanol will do for mineral oil removal? However....the label on the "Bona Woodline" brand "oil-modified" polyurethane I bought says "not recommended over shellac".


Denatured is better, less water. "oil modified" just means it has a modified oil that is converted in to di or monoglycerides which contain hydroxyls in it and then can be reacted with the isocyanate/urethane. It really doesn't contain any real true natural oil. As to shellac incompatibility, they probably mean shellac that contains "wax", you will use zinsser "sealcoat" which has no wax whatsoever and was developed to go under and be compatible with all polyurethanes. 

Call them and see if what I'm saying and believe to be the case is correct just to be sure OK?

If by chance they say even sealcoat won't work, then they have an incompatible alkyd or solvent or maybe an amine like DMEA that would be detrimental to the shellac or other chemicals, the list is long. If so then you can either switch brands or if they have a compatible sealer that will go over the oil contamination, without problems, then use it.


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## BenKangas (Mar 27, 2012)

Wow, most helpful...thanks a lot.


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