# Finish for Spalted Maple



## JPrictoe (Jun 24, 2017)

I used a coat of tung oil to finish some coasters I'm making for a project out of spalted maple and the color actually came through pretty well. There is a laser cut in the middle of each coaster, and I'm worried water and/or exposure from the relief cut by the laser will rot or mold the wood (more than the already spalted nature of course). Is this a real concern? I can already see some white furries appearing in the relief cut of one of the coasters, not sure if they were there before



















Any suggestions on a top coat? Do I need to do anything more or is one coat of tung oil sufficient? Thanks! Images attached.


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## ArtMann (Mar 1, 2016)

I hope you really want to know the truth on this question. I make and sell CNC carved coasters. I don't need for my stuff to warp or split when someone leaves a cold wet drink on it. I can tell you that Tung oil will do practically nothing to prevent that. After a good deal of experimenting, I have settled on spray solvent polyurethane as a finish. Several brands work about the same but I use Minwax because it is inexpensive and readily available. I usually use 3 heavy coats. I am looking at a coaster on my desk at this moment which has been in daily use for 2+ years. It is starting to warp and the poly is turning loose around the edges. That is about as good as you are going to get. Here is a photo of what a new coaster I built looks like.


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## HokieKen (Apr 14, 2015)

I agree with Art. I would use an oil finish like you did to bring out the colors of the spalting but I'd top coat it with an oil-based polyurethane for protection against moisture. Coasters will always see direct moisture contact (if they're used) and moisture will eventually damage most any wood under those conditions.


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## RichT (Oct 14, 2016)

I spray my coasters with lacquer. I've got one I've been using for almost 3 years and it's still looking good. I will say that the wood is mesquite, which is quite durable on its own.


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## LesB (Dec 21, 2008)

Oil finishes do not resist moisture very long but you might apply it first for to enhance the color of the wood. Let it cure (oils do not dry they chemically cure in the wood and mineral oil never drys or cures). I like to use processed Walnut oil for this purpose instead of linseed or tung oil. It cures faster than the later two. 
Then spray on 2 or 3 coats of poly or marine grade lacquer as a protective coat. Note: poly finishes do not add color to the wood unless you get one of the tinted types they are clear so it used alone does not always enhance the wood color.

One more thing. Spalted maple may be quite porous and absorbent so a couple of coats of oil finish will help seal it before you apply the top coat. Another choice is to use 2 or 3 coats of *de-waxed* shellac to seal the porous wood (you can get it in clear or amber colors to help enrich the the wood color) and then use the poly top coat. Shellac drys very quickly so multiple coats can be applied in just a few hours. Of course sand lightly with 320 or 400 paper or rub with 0000 steel wood before applying the top coat to remove any roughness.


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## JPrictoe (Jun 24, 2017)

Thanks everyone. I'm away from the shop for the holidays, so I think I'll go with the shellac and a top coat of poly. Definitely appreciate all the suggestions, and yes Art the truth hurts but I knew it was coming haha.


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