Finish for Spalted Maple

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Forum topic by JPrictoe posted 12-19-2018 02:31 PM 697 views 0 times favorited 5 replies Add to Favorites Watch
View JPrictoe's profile


6 posts in 946 days

12-19-2018 02:31 PM

Topic tags/keywords: question maple finishing

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.

5 replies so far

View ArtMann's profile


1462 posts in 1426 days

#1 posted 12-19-2018 04:31 PM

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.

View HokieKen's profile


12010 posts in 1748 days

#2 posted 12-19-2018 04:48 PM

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.

-- Kenny, SW VA, Go Hokies!!!

View Rich's profile


5153 posts in 1199 days

#3 posted 12-19-2018 05:06 PM

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.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View LesB's profile


2318 posts in 4053 days

#4 posted 12-19-2018 06:10 PM

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.

-- Les B, Oregon

View JPrictoe's profile


6 posts in 946 days

#5 posted 12-19-2018 06:25 PM

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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