Mfgr Says Use Only Silicone! WTH...Everyone Here Says Don't Use Silicone.

[jongleur]

kthoennes:

Actually, acetone is not very toxic at all. Your body makes a certain amount of it all the time. If it were toxic, manicurists would be walking zombies, and they're not. Check it out on wikipedea.

[CarinaPDX]

The proper way to do the screw holes is to drill them out so they have clean, hard sides. Otherwise the sides have loose glass fibers and resin created by the threads crushing the glass, and that is not good for adhesion. Similar for the gash: it should have been ground or sanded to smooth with no crushed fiberglass or fibers showing. Then clean with suitable solvent, and allow enough time for all of the solvent to evaporate. I don't use acetone anymore either - methanol usually does the job.

Greg

[Hudson Force]

Originally Posted by CarinaPDX

The proper way to do the screw holes is to drill them out so they have clean, hard sides..............
Greg

.....and then follow this with filling the voids with epoxy. 5200 excells as a bedding compound, but not as a structural filler.

[Maine Sail]

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 and fiberglass. 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..

[s/v 'Faith']

Originally Posted by Maine Sail

?....

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 and fiberglass. As of yet none tested have been both safe for the fiberglass and also good at removing the silicone.....

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..

Glad you chimed in. Lots of people seem to be overlooking this problem.

Once the silicone gets into the fiberglass, it is not coming out. Sanding can make it worse, and it does not wash out with conventional solvents.... I know you are working on a commercial project, but I would really like to hear about your testing methods....

For most applications, silicone is evil and does not belong in use as a general sealant aboard boats.

[boatsail]

Interesting. I neveer thought that the product is often sold and told to be used, but no "remedy" to remove has been presented. Could it be that one cannot exist and if there was one, it would be recommended by the people who make the silicone in the first place. Interesting, never thought of it.

[s/v 'Faith']

Originally Posted by boatsail

Interesting. I neveer thought that the product is often sold and told to be used, but no "remedy" to remove has been presented. Could it be that one cannot exist and if there was one, it would be recommended by the people who make the silicone in the first place. Interesting, never thought of it.

Yes, they market "release agents" that assist in breaking the (relatively weak) bond, but there is no solvent that cleans silicone oil out of gel coat or fiberglass.

[hellosailor]

Mark Plastics also recommends silicone only. I suspect this is because silicone will do the job at the lowest cost, and it is fairly easy to break the ports back out when they do need servicing. Anything better would make that job harder. And any kind of plastic will eventually need replacing.

[boatsail]

Hello sailor, true, but to be honest, my windows were in for 34 years! I wouldn't mind going through hell to get them out once or twice in a lifetime if it guaranteed no leeks.

I will be using the 795. And mark was awesome in regards to his knowledge. I am going to order my two fixed ports from him.

[CarinaPDX]

Of course there is always the option of upgrading to metal portlights...

You're a rich yachtie, right?

Greg

[keyspc]

There is only one use for silicon on a boat
.
.
. Breasts

[CarinaPDX]

Ouch! Silicon would be mighty hard. Perhaps silicone would be better?

Greg

[sartorst]

What I have always wondered was why something that was so hard to remove and bonded so well leaked so much on boats/fiberglass but worked well on car engines in extreme temps? movement ?
By the way if I were to recommend a product to use and I was covering my but I would say silicone BUT if I did not won't it to leak it would not be silicone!

[hellosailor]

"What I have always wondered was why something that was so hard to remove and bonded so well leaked so much on boats/fiberglass but worked well on car engines in extreme temps?"

Worked well on car engines? When Permatex first tried to market "Form-A-Gasket" mechanics hated the stuff. It doesn't work, it leaks, the stuff is crap, they all shouted.

Even though Permatex had built an Indy car engine sealed with no conventional gaskers, just their sealers. How could reality be so badly different? Easy. The stuff only works when it is used according to directions, with the right prep, the right cure, the right installation, the right application.

Same thing with silicone on boats. It does the job it is stated to do, when used according to the instructions. When folks just goop it in, or goop it over wax, or expect it to bond to plexi, it also fails. Just as stated it will.

What was the Porsche mechanic's line in "Risky Business" ?
"Who was playing U-boat commander?@!"

[jongleur]

Just as I suspected. Therefore no
sillycone will ever be on any of my boats.

Another reason: If it cracks after cure,
from too much movement, it creates perfect
little wicking channels that can never be
fixed.