Originally Posted by Chotu
Attached, please find some pics of what Dow 795 does when used as a sealant
with large pieces of polycarbonate.
Is there a better, more flexible and resilient sealing material I can use just to seal the gaps? Not looking to take any structural load with the sealant. Just looking for something that will not crack as things expand and contract
. Something that stays stuck on the polycarbonate and the hull
but gives really nicely in between the two.
I've had this problem due to expansion/contraction of the polycarbonate window, especially on the sunny side of my boat
. I've had to reseal my windows twice; originally used 4200 not so good after a year or more, then switched to 795. First taped off the cabin
trunk around the window edge about 3/16 to 1/4 inch then applied a generous amount of sealant along the 9mm window edge, then used a rubber caulking finish tool to spread sealant and allow to over hang the edge of the window. Pull the border tape off within a few minutes otherwise one will pull up the sealant. After sealant cured trim the over hanging cured sealant with a razor blade. In time the sealant separates creating small leaks
that develop at the outer edge of the window in specific areas. Frustrated, I then used Permatex black silicone adhesive
sealant bought at auto part store to add to the small leaks
, and it has worked through the rest of the summer. When I reseal the window again if necessary, will use 795 as have a tube waiting. Be sure to clean the area well with denature alcohol or acetone prior to application. I understand some people think that silicone should nor be allowed on a boat
, l but in this case it worked.