Can I use linseed oil and water-based polyurethane on opposing sides of a 1/2" board?

Question

I know that linseed oil and water-based polyurethane won't work together. But I have 1/2" poplar paneling that I am installing in my van and am hoping to get the best of both synthetic and natural properties. I like that the linseed oil soaks into the wood and would help prevent splitting on hot days however it turns the wood more yellow than we'd like. On the other hand, I heard that water-based polyurethane would keep the wood with the most natural look keeping it mostly white bright, although it might not prevent the wood from splitting as well as linseed oil.

I already applied a coat of linseed to one side of a few of the boards and looking at the ends, it looks like it penetrated halfway through the next morning. i was thinking what if I applied linseed oil to the back of each board (they are 1' x 4 ft vertical panels) and applied water-based polyurethane to the front facing inside of the van - could I get the best of both worlds????

Let me know what you think!

Thanks!

Answer 1

Just to answer the question in the title, yes you can use linseed oil and waterbased poly on opposing sides of board if for some reason you wanted to.

I know that linseed oil and water-based polyurethane won't work together.

Actually they can. After curing drying oils aren't oils any longer, the oxidation process has turned them into something else (a natural polymer) and it is possible to use waterbased products over wood treated with them.

The oil should be quite 'dry' before applying a waterbased product on top* but if a bonding problem is found shellac can be used to effectively bridge between the oiled wood and the waterbased finish.

I like that the linseed oil soaks into the wood and would help prevent splitting on hot days

Actually it won't. Oils are in fact very poor at preventing water transmission so as counter-intuitive as it seems they are not good at preventing cracks due to drying.

I heard that water-based polyurethane would keep the wood with the most natural look keeping it mostly white bright

Yes this is correct. At best the wood can look like it's still bare, useful if this is the look that's desired but some protection is needed.

although it might not prevent the wood from splitting as well as linseed oil.

If the product is of a decent quality then it should be better at this, markedly better in fact.

However, if you're having significant problems with wood splitting that signifies a fault in the wood and it's not really something you should be seeking to prevent with finish. Better wood is the answer.

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*Overnight drying is not nearly long enough in this case. At least a week is a good idea, longer would not hurt up to about a month after which no improvement is likely to be found.