Silicone fumes

[Flavius]

Assuming a box with drivers already mounted, in order to finish it have to attach the back cover using silicone as sealant. Naturally some silicone fumes will develop inside the box. Are they dangerous for the drivers? I might put the box to work at once to circulate the air.... Thanks.

 

[pinkmouse]

Hi Flavius

It would be better to let the box sit for a while with no drivers in it, but rinning the box will probably work. Actually thinking about it, the silicone mostly produces acetic acid, and this probably won't cause any harm, but better safe than sorry

 

[hurdy_gurdyman]

Silicne ll has seems to have a lot less fumes the the origional type silicone.
Dave

 

[Flavius]

Ahhh and i was complaining im out of vinegar for my salad


Seriously now, I cant reverse the system my box assembles, the drivers must stay.

Actually in my original project i wasnt using any silicone, just glue where its supposed to be closed for good, while the midbox plate and the backplate where sealed with rubber foam gaskets.

But the glue where one midbox was attached to the baffle seems to have cracked, and at very high levels I was getting a buzz I had to put everything apart and in the process of reasembly I discovered silicone its handy stuff to use

 

[Variac]

Polyurethane sealant like Sikaflex is better than silicone in almost every way. It is waaaaay more adhesive the only down side is that it is almost impossible to take things apart that have been sealed with it. Also stickier to work with and harder to clean up, but I hear alchohol helps clean it.

 

[leadbelly]

the silicone mostly produces acetic acid, and this probably won't cause any harm

Well, the consensus (if there is any such thing in a forum) over at diysubwoofers.org is that traditional type (ammonia based) silicones are very bad for drivers, with horror stories to back it up.

I believe some, if not all, latex based silicones are OK.

Whatever your opinion on the issue, DO NOT install the drivers when there is still that heavy ammonia/vinegar smell in the air.

 

[Flavius]

Uhh, I guess I'll stick to the rubber foam gasket after all....

Next set of speakers will be designed in a way that the box is finished before I'll have to mount the drivers....

 

[pinkmouse]

Well, the consensus (if there is any such thing in a forum) over at diysubwoofers.org is that traditional type (ammonia based) silicones are very bad for drivers, with horror stories to back it up.

Hmm, silicones over here in the UK don't seem to have ammonia in them, I just checked the label of some I have lying around and the chemical warning notes don't mention it. I wonder if it's another transatlantic difference we can mark up?

 

[roddyama]

Silicon sealants/adhesive for the automotive world went through a big change about 10 to 15 years ago. Hence the mention of silicon II by Hurdy-G (also from Michigan). It seemed that the old silicon sealant was putting out too many emissions. These fumes, were not very good for us to breath and they were also attacking various polymers used in the vehicles, like foam rubber. Today in the automotive industry only low emissions silicon sealants are used. You still have to be careful because this will not be the case for the general stuff you might get from the Home Depot.

 

[leadbelly]

I found a good link which at least describes what variety there is in consumer brands of caulk:

http://www.pwgsc.gc.ca/rps/aes/content/ercr_handbook_appenda11-e.html

But it actually leaves me with even more questions. Firstly, the tubes of caulk I have at home don't list ingredients. Secondly, I'm not sure if the reports of surrounds being destroyed on diysubwoofers.org can be attributed to the vinegar in silicone evaporating or instead to caulks with petroleum solvents.

 

[kelticwizard]

I tried to attach some surrounds with silicone once. It seemingly worked great, but a few months later simply peeled off.

Also, I called up the makers of the excellent epoxy glues, PC-7 and PC-11, (not cheap but I find them amazingly useful), and they said that once silicone has been on something, it is almost impossible to put any glue on it. That is, silicone has indeed some adhesive properties, but once you take it off forget about using any other glue. I have sanded down bathtub enclosures that were sealed with silicone, and after some sanding, found that they will take another glue, once the layer with silicone is sanded off.

Silicone would not be my first choice for gluing the back of a speaker box on.

 

[kelticwizard]

Hmm, silicones over here in the UK don't seem to have ammonia in them, I just checked the label of some I have lying around and the chemical warning notes don't mention it. I wonder if it's another transatlantic difference we can mark up?

As soon as they came out, I noticed that silicone sealant, when drying, smelled like vinegar. And since acetic acid is acid, and ammonia is a base, I am not sure that the both can coexist in the same substance. I would think they would form a salt and not go off into the air. Don't hold me to this-I am no chemist. But I never heard of ammonia being associated with silicone sealant.

 

[Pjotr]

Hi,

Well, there is a kind of silicone compound without acid. It is used for mounting mirrors because it does not attack the silver layer on the back of mirrors. Maybe a shop that sells custom cut mirrors can help you. At least they sold me a cartridge in the past.

Cheers

 

[roddyama]

For gluing wood or wood products, I’ve always used white or tan wood glue (like Elmer’s). For sealing enclosures, I’ve always used gaskets.

 

[NH7RO]

Hmm, all this talk about silicone fumes makes me all the more ready to go with dipoles in lieu of any kind of sealed box....