If you want to install Beckson ports
then by all means use a commercial
glazing silicone like Dow 795 or GE SG4000.
Other sealants such as polyether, polysulfides and polyurethanes can leech the plasticizers out of the Beckson products and make them prematurely brittle. The plasticizers that are added to the material keep them from becoming brittle and cracking.
I generally don't recommend butyl for Beckson ports
, it won't damage them, but, butyl needs to be in compression
to work best. Unfortunately the Beckson ports are not very robust, compared to bronze, SS or even aluminum
so when you try to compress the port against the hull
they flex and compress at the screw hole, if not done slowly and with care. I do have customers that have used it but I personally suggest listening to Beckson. Either way the trim ring is best applied "glued on" with a product like Dow 795.
Yes silicone contaminates but there are some places where it is still the best product. I always have tubes of Dow 795 here in my shop. It is cheap
, I pay about $7.95 from McMaster Carr, and a very good product as silicones go.
I recently spoke with Cyro Plastics the makers of Acrylite GP, which is used in most hatches and portlights
, about polyether sealants such as 4000UV and their answer was "We've tested it and it is not a recommended product for use with Acrylite GP.".. I have no idea about Beckson & UV4000 other than they suggest using silicone and don't suggest UV4000 is safe.. Sikaflex 295UV can be used on Acrylite GP but you must use the special primer with it. I have never seen Beckson say Sika 295UV is safe for use on Beckson products however.
The biggest issue with ANY sealant
, not just silicone, is improper preparation and cleaning
of the fitting and surfaces to be bedded.
Most don't know this but for nearly two years I have been working with a couple of chemical manufacturers to develop a "silicone remover" that works on gelcoat
. As of yet none tested have been both safe for the fiberglass and also good at removing the silicone contamination.
My ultimate goal is to market a product to the marine
market to solve this issue, if I can come up with a formulation that works as advertised. This is proving to be extremely elusive.
It is my guess that I have probably done more physical controlled testing of silicone removal
on fiberglass/gelcoat substrates than anyone else in the marine
industry. It has cost me well into the four figures category and as of yet NOTHING has proven to work. I have now passed my tenth formulation, still have nothing worth selling to the general public, that I would put my name on..
I have also tested every single
"internet cocktail" to be mentioned on internet forums
and none of those has even come close to working on cured silicone.
Every wonder why everyone is willing to sell you silicone products but no one markets an effective silicone remover that is safe for use on gelcoat
.....???? The answer is it is very hard to do, and may prove impossible, but I am still trying..