Bob Flexner in his excellent book “Understanding Wood Finishing” has some pointers for this situation on page 169. Some combination of the following should work, but keep in mind that Joe was thinking about furniture when he wrote this, not boats:

1. Remove the silicone oil from the wood, with mineral spirits, VM&P naphtha, or special silicone remover; these are only partially effective, because they thin the surface oil, but don’t pull it out of the wood pores. TSP mixed with water is a standard prep treatment prior to painting, and will remove the oil from the wood, at the price of soaking the wood with water, requiring additional sanding and perhaps emulsifying glue lines. If the contaminant lies on top of the epoxy and glass, TSP should work just fine.

2. Seal the silicone in the wood, by spraying on a coat of shellac. The vehicle for shellac is alcohol, which will not dissolve the oil, which then becomes encapsulated beneath it. Spraying is critical, though; brushing will only drag the oil around and compound the problem.

3. Spray on several light coats of nitrocellulose lacquer, with the same proviso as for shellac.

4. Lower the surface tension of your varnish, by adding small amounts of the same contaminant that caused the problem in the first place. Assuming that you are sure the contaminant is silicone, this counterintuitive method requires mixing in some silicone oil into your varnish. This product is sold under several trade names, including Fish-Eye Destroyer, Fish-eye Flo Out, Sil Flo, and Olde Smothie. Add 1 or 2 eyedroppers per quart, or follow the manufacturer’s instructions. Less surface contamination requires less additive to bring the surface tension into equilibrium, and vice versa. NB: this boat will forever require silicone oil additive for repairs or refinishing, your application equipment will be contaminated, and overspray will contaminate any other finished or unfinished wood in the area.

I would be chary about encapsulating the oil with either shellac or lacquer, because neither product is suitable for use below the waterline. Should water get into that bondline through any mechanism, cancer could develop and require stripping and refinishing. IMHO, adding and spraying silicone oil is worse. So, try TSP and hope for the best. Good luck.

: At the suggestion of an experienced woodworker on a kayaking listserv, I put
: 303 on the deck of my Betsie Bay boat. It needs refinishing, which is to
: happen in July, and the silicone was recommended as an interim way to
: prevent UV degradation. I've just learned from Betsie Bay that this was
: about the worst thing I could have done to the boat as it will is
: well-nigh impossible to remove and will make the future finish bead up
: instead of holding to the deck.

: Does anyone have any suggestions for how to get it off?