Hi Chris,
Good timing. Chad's strakes have been ready to close for a couple of months. We had Jeffco ready to go when we read of your problems (thanks for that). Based on your problems / pictures, Gary's comments and other reported good experiences with Proseal, the Jeffco has been returned and a Proseal kit was delivered today. I think that lays out our thoughts on the subject of which sealer to use. As it happens, Proseal is also MUCH less expensive.

One thing I think you may be missing in your tests - could it be that it's the ethanol vapor, not the fluid that causes the most damage? If this is the case, then full immersion may not give you accurate results compared to a skin thats exposed mostly to the vapor, as the top skin will be.

After 2 years in Florida and two years in Connecticut, my MGS 335 built tanks still have no leaks, but they ARE showing some signs that I'm concerned about. What I'm seeing is slight distortion on the flat top of the strake, mostly on the pilot side. It doesnt take much change in shape to be immediately visible. Where I once had a perfectly flat strake, the skin in the center of each compartment has now moved downward slightly (maybe 1/8 inch vertically) such that there are now bumps showing where the ribs are located, and the smooth curve I used to have on the top front of the strake is now a series of angles where each 1 inch of foam is a little flatter than the join. I'm also seeing quite a bit of "print through" of the weave on both top and bottom skins, especially where the ribs join. The problem on the curved front and the print through "could" be micro shrinkage, related to the plane being built at 90F and then suffering 0F winters, but I don't see any similar signs elsewhere on the plane, so I think all these symptoms may be related to ethanol (and whatever else they put in gas these days). I suspect that the inside skin has reacted to the ethanol and expanded where it can while the outside skin has remained unaffected. A few months ago I drained the tanks and scratched the bottom of the tank with a screw driver. It seemed entirely solid. I'm keeping a close eye on it, but I suspect that replacing the strake skins and buying some proseal is probably in my not-too-distant future. That's not really the catastrophe some might think. I can probably do both strakes in a week. Hopefully the proseal will protect the epoxy and save me having to do the job every five years.

I hope this helps.
John