Does butyl tape every dry out?

[ILikeRust]

After reading the great threads here recently about the wonders of butyl tape, I pretty much had concluded that's the way I'm going to re-bed my grabrails and a couple lifeline stanchions. One of the several things that sounded good was the statement that it stayed flexible pretty much forever.

I mentioned it to an acquaintance of mine who has a very nice boat he built about 40 years ago and has been maintaining ever since, and he said that the problem with butyl tape is that it eventually dries out.

So what's the deal?

[Maine Sail]

If it "eventually dried out" then it was either not butyl or a very low quality product calling itself butyl tape. There are a number of low quality products out there mistaken for butyl or even called butyl tape by some re-sellers. I am sure it "dries" to some extent but not to an extent that it is an issue. I have removed 30 year old fittings bedded with butyl tape and the stuff was just as sticky and gooey as it was when installed. Up until about two months ago I was still working off a case I bought back in 1996 or 97. It still worked perfectly. When I compared it to the brand new stuff the only difference I could detect was that it was tougher to peel of the waxed backing paper. After ten+ years it must have really bonded to it.

I have recently sourced the original stuff used by boat builders to be able to supply to other boaters because no one else is doing it. I can hardly keep up with the orders.

Feel free to show your friend the picture below. It was taken at 29 years old and the butyl was still very, very, flexible, sticky and gooey. Oh, and this cleat had not leaked one drop of water in 29 years..

Considering the thickness under this deck cleat was likely 1/64th of an inch thick or less we are looking at an elongation or stretch into four digits as a % even at nearly 30 years old.

[mitiempo]

I'll second what Maine posted. My hull/deck joint is bedded with butyl and the small amount that is exposed inside at the joint is still as flexible as the new roll I have. I just removed my forward hatch that was also bedded with butyl 33 years ago and it was still flexible as well. Also leak free but the hatch was in need of a major rebuild. I elected to replace it with a Lewmar and butyl is the bedding being used.