Silicone Corrosive?

Status
Not open for further replies.

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
I just read in a vehicle maintenance book that silicone has ammonia and is corrosive to wiring. I had never heard that before. I've seen silicone used to seal outdoor coax connectors and I have used it a lot to seal small holes in enclosures, caulk enclosure to wall, etc. Haven't specifically used it on wire, but I'm sure some gets on it 1 way or another.

Has anyone else heard of this issue?
 

renosteinke

Senior Member
Location
NE Arkansas
The article was somewhat correct. There are non-corrosive silicones available.

It's not ammonia; in curing silicone reacts with moisture in the air, and this makes acetic acid (vinegar). If these fumes are not vented, they will harm things like relay contacts. That's whay there are 'electronics grade' silicones sold.

Not a problem on the side of a house. A real problem if you use it to 'weatherproof' an alarm panel.
 

sgunsel

Senior Member
Most silicone RTV products release acetic acid vapor (not ammonia) when curing. You have probably noticed the odor when using the stuff, it smells like vinegar. If confined, this acidic vapor will corrode copper. Actually it chemically combines with copper to make copper acetate, which has neither good conductivity nor mechanical strength. If used where the fumes can dissipate, no problem.
 

Electric-Light

Senior Member
Some release ammonia, some release acetic acid. Some release some strange smell that doesn't fit either of the two. That's the one you want.

I think the copper colored Permatex brand gasket maker is the third type which is sold for automotive use. If you could tolerate the copper color go with this. You could also try hunting down "non corrosive RTV"
 

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
I've noticed a strong smell, but not vinegar like. Then again, my smeller isn't what it used to be. I'll have to check out the silicone brands at supply houses. I don't generally use it directly on any wire, but have used it to seal better around a connector into a meter base or panel. If I can get a safe type at good price, that's all I will use. I'm sure some incidental contact occurs if I seal gaps & holes with it & press wire in when covering the enclosure, & fumes will be in there too.

I never even thought of that, after seeing it used on coax, etc. I never saw any labeling that a variety was unsuitable for wire contact, etc. It may have been there.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I've noticed a strong smell, but not vinegar like. Then again, my smeller isn't what it used to be. I'll have to check out the silicone brands at supply houses. I don't generally use it directly on any wire, but have used it to seal better around a connector into a meter base or panel. If I can get a safe type at good price, that's all I will use. I'm sure some incidental contact occurs if I seal gaps & holes with it & press wire in when covering the enclosure, & fumes will be in there too.

I never even thought of that, after seeing it used on coax, etc. I never saw any labeling that a variety was unsuitable for wire contact, etc. It may have been there.

That's because the solvent in most silicone products is MEK, not acetic acid. Acetic acid is used in RTV, or Room Temperature Vulcanizing silicone rubber products. Those are used in place of gaskets, not as a filler type sealant the way we use silicone.
 
Last edited:
Status
Not open for further replies.
Top