Choice of sealants for plastics

[James384]

I had a discussion recently with Tim regarding what sealant is best for a job I was doing replacing a cabin port that had a a deteriorated rubber gasket between glass window and aluminum frame. I ended up discarding the old gasket and sealing the aluminum frame to the fiberglass as well as the glass to aluminum with polysulfide Boatlife Lifecaulk. The Lifecaulk was difficult to work with because it skins over in about 5-10 minutes in the 90 degree days down south - not nearly enough working time. I was going to try 3m 101 but could not find it locally on short notice. Tim suggested trying glass butyl caulk, possibly from a glass shop supplier.

My question now concerns sealing plexiglass or lexan to aluminum, bronze, or wood. What is the best sealant to use? Are there any cheap equivalents to the marine sealants that are just as good and stocked at places like Home Depot or must we continue to pay for "marine" brands?

I remember replacing the lexan on a Bomar hatch and the replacement glass came from the factory with a type of GE silicone, I believe. It worked very well but now I'm not sure what it was exactly, where it's available and if there is an alternative. Does anyone have any suggestions, good or bad experiences?

Thanks
James
#384

[kaynee30]

I used the butyl from Sherwin Williams...for aluminum gutter sealing...to affix the 10mm Lexan into the large frames and the cabin....at Tim's suggestion...."guaranteed" 20 year service. Cheap. And it won't embrittle the Lexan as 101 apparently does over time. I think it was $3.80 a tube. I cleaned my mom's aluminum gutters that were sealed with butyl about 20 years ago....the stuff is still pliable and stuck to the aluminum ...even where exposed to UV. And that had to be cheap butyl....contractor's job....dubious quality. I'm thinking of re-gooping my chainplates with it........instead of the 101.......cuz the 101 keeps failing. I think the butyl might stick better to the chainplates, and be a lot more flexible.
Jeff