Proper sealant to use on hatch between “glass” and aluminum frame

What is the proper sealant to use between the Lexan ?? And the aluminum frame of the hatch. These are bow hatches. Thanks for your time.

What's the aluminum coated with?

I don’t know.

lexan is Polycarbonate and I believe pure silicone is a good sealant. Aluminum could be painted, powdercoated, anodized or clean.

Im not sure whats best for that bond.

BobK please chime in.

I’ve seen silicon and 4200 used.

Thank you both for your help. I really appreciate it.

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Originally Posted by Boatsb

lexan is Polycarbonate and I believe pure silicone is a good sealant. Aluminum could be painted, powdercoated, anodized or clean.

Im not sure whats best for that bond.

BobK please chime in.

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Polycarbonate is very easily damaged by some solvents. I would check with a plastics supply house rather than reinvent the wheel. It is also not very UV resistant.

Silicone caulks come in several flavors. The common one releases acetic acid when it cures which may damage the aluminum. An architectural polyurethane may be best if it will not damage the PC.

Bobk

`Dow 895 is what is used by most that rebuild them.....Pat

I don't know about Dow 895, but I use Dow 795 which is a commercial grade silicon, my entire aft deck enclosure is put in with the 795. It is plexiglas but it is also good for lexan and regular glass. As I understand it the windows in skyscrapers are glued in with 795. Only problem with it is can be hard to find. We found a place that was a boulders supply and they sold it to me at wholesale pricing and it was surprisingly cheap. The guy that replaced my solid glass windows on my last boat used it also. John

Boatlife Life seal. Its a combination silicone/polyurethane. Its safe for Lexan. I used it on my hatch years ago and its still watertight.

Read about it here:

http://www.boatlife.com/lifeseal-sealant-cartridges/