Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
(OP)
We have an old drawing that said to use Dow Corning #4 Insulating Compound to cover a few connections in a power supply... recently I noticed that the shop is using waterproof window/door/attic/basement 100% silicone... the kind you can get at lowes for your home... is this an adequate replacement in your opinion?
I will call Dow Corning and ask... but not sure how honest they will be about the comparison. That is, I assume they will try and say their product is superior just to sell it... Thanks.
I will call Dow Corning and ask... but not sure how honest they will be about the comparison. That is, I assume they will try and say their product is superior just to sell it... Thanks.





RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
AFAIK, all/most of the silicones sold at Lowes are caulking. They dispense like grease and cure into rubber shortly after application.
Common silicone rtv formulations release acetic acid during cure. You may notice the vinegar odor. It's real vinegar, and will corrode electrical connections. Not good in a power supply, or anything else electrical.
The special RTVs specifically formulated for use in electrical service use a different cure mechanism, and don't release acetic acid.
Some of those electrical silicone RTVs are 'self-leveling', which means they ooze out for a while (until you breathe on them), then cure into a rubber that stays shiny and wet-looking. Those in particular make really zoomy covers/ strain reliefs for electrical work. Once cured, they don't just wipe off, and they're not all that easy to cut off, either.
Mike Halloran
Pembroke Pines, FL, USA
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
A household caulk - even one stated as 100% silicone, is not 100%, but will have some additives for UV exposure, and blended to a viscosity and properties to make it easy to apply in a home construction environment.
I recently took apart a 1.5kw off-brand made-in-china power inverter, and found some really poor construction. Among other things lots of silicon caulk were used - the type for bathtub caulk filled with lots of gypsum/chalk and other fillers.
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
GE sales confirmed that the acetic acid could be bad on some of our connections that are copper and brass.... they said that the household silicone would be ok to use as an insulator on harder metal electrical connections though... for whatever thats worth coming from a sales person from GE...
We will be using the real electrical compound from now on...
Have a good one!
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
USAeng - What sort of power supply are we talking about here, and what is the silicone actually being used for? I mean, using it to dampen vibration on a tall through-hole component is obviously less critical than protecting against corona/arcing from a solder joint on a pc board.
At any rate, the type of silicone preferred for electronic uses releases methanol and ammonia when it cures rather than acetic acid. Silicone is highly resistant to damage from UV all on its own so it is not necessarily the case that anything was added to the "100% Silicone" from a home improvement store to make it more UV resistant.
No comment on the appropriateness (or lack thereof) in using non-approved products/components....
RE: Differences in silicone? Dow Corning #4 compared to 100% GE Silicone
Thanks again for all the comments