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Est. 1998 — 27 years of woodworking knowledge

A55 Smoothing Plane

finishing

Posts

finishing

#1

finishing

Klaus Arnold

>Does anyone have a solution to my problem? I built a fireplace mantel out of cherry and stained it with an oil base stain. I've been trying to get a good polyurethane coat on to complete this project but to no avail. The poly after being applied seems to pull away from itself leaving what I can best describe as, " pox marks." I've tried brushing it on as well as spraying it on with the same results. The polyurethane I've used has all been from the same can which I bought at the local Home Depot off the discount shelf. Any chance that it has been contaminated with something or am I just screwing something up? Any help would be appreciated.

Re: finishing

#2

Re: finishing

Tom Pilsbury (Chicago)

>I'm probably the last person who should be answering your question but I'll give it a shot till someone more knowledgable comes along. I'm thinking you might be using a water based polyurethane which is not compatible with oil based stain. Check the label.

Re: finishing

#3

Re: finishing

Paul Dwight

>Your "pox marks" sound like "fish eyes," which most commonly result from something like silicone contaminating the surface. Any chance someone wiped the piece with furniture polish before you applied the poly? That would do it. Sometimes a tack cloth or even a paint brush can pick up silicone contamination if, for example, they're laying on a workbench when you use a spray lubricant like WD40.

To deal with the problem now, you have basically two choices. First, you can try to seal the contamination in with a coat of dewaxed shellac like Zinsser Seal Coat, and then topcoat as usual. The shellac will probably keep the next coat of poly from developing fish eyes. The downside is that you're still left with low spots over all the fish eyes that were present in all the coats that went on before the shellac. The second choice would be to strip the poly off and start over. Once you're down to bare wood again, wipe the piece thoroughly with acetone and a clean rag. When the workpiece is dry, seal with shellac and then start building up the poly topcoats.

Dealing with fish eyes is a pain in the rear. Good luck! -- Paul

Re: finishing

#4

Agree With Silicone Contamination

George@Colonel's Workshop-Havertown PA

>Good Morning Klaus,

I've had to deal with silicone contamination several times. It is a real PITA. I think that is what is causing your fish eyes. You should definitely strip the mantel down to the bare wood, and complete the project as Paul suggests. Definitely provide a shellac barrier over the stain. You should expect good results. You should also carefully examine your shop to identify and eliminate any silicone source.

George

Re: finishing

#5

Re: finishing

Howard Acheson

>What stain did you use? How did you apply it?

What clear finish are you using exactly?

Never buy finish off the "discount" table. It gets there because either the can is damaged, has been opened and/or because it is old. YOu always want to buy the freshest finish.

On another point to another responder, WD-40 does NOT contain any silicone.

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