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Old 01-18-2011, 02:59 AM   #11
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Dow Corning 732 is 100% silicone. No solvents, no volatile compounds. How is this different than using a silicone o-ring?
Not True. Dow Corning 732 contains 1-5% Ethyltriacetoxysilane and 1-5% Methyltriacetoxysilane.
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Old 01-18-2011, 03:19 AM   #12
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The volatile compounds should be just that - volatile. The silicone will off-gas for a number of days before it is fully cured. Eventually, those volatile compounds are essentially gone. Nothing like a good test boil to move that process along. I'm betting that the risk from the cured silicone is pretty darn low. Literally. I used White Lightning silicone for my heat sticks. Life entails risk. I'd worry more about driving home.

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Old 01-18-2011, 04:02 AM   #13
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I believe o-rings and sheet stock are made in a similar manner as one would seal something up with a tube of silicone, by spreading/extruding/molding the silicone and letting it cure. Yes, as Chefkeith pointed out, the curing agent isn't silicone, but if cured properly should volatilize out of the silicone. I would cure as long as possible and keep whatever is being cured in the driest place possible. Direct contact with water usually slows the curing process,iirc. No less than the mfg recommends, but short of a year...

Vinegar comes to mind as a curing agent and acetic acid may be the fancy word for just that. Anyone know what Ethyltriacetoxysilane and Methyltriacetoxysilane really are?

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Old 01-18-2011, 04:50 AM   #14
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I would also agree that the risk is low, but people should be aware of it.

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Old 01-18-2011, 05:18 AM   #15
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Upon further research, Ethyltriacetoxysilane and Methyltriacetoxysilane seem to be slight variations of some of the precursors to silicone which cause cross-links in the polymer that enable it to vulcanize when exposed to the moisture in the air at room temperature; hence room-temperature vulcanization (RTV). So, they may not be volatile organic compounds after all (though I still see brands of silicone sealant that are labeled "low VOC."

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Old 01-18-2011, 06:00 AM   #16
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Follow Kals link on www.theelectricbrewery.com and order the FDA approved silicone that is linked to McMaster Carr.

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Old 01-18-2011, 12:24 PM   #17
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I would also agree that the risk is low, but people should be aware of it.
The risk of what?

You are correct, silanes can be pre-cursors to silicones. Silicone is a class of compounds, it does not refer to a specific compound. There are many silicones and many silanes. Through hydrolysis, a silane can turn into a silicone, realeasing acetic acid. I ingest acetic acid all the time. Since the acetic acid is released as a gas and removed from the environment of the reaction, and there is an unlimited supply of water vapor(a reactant) in the air, the reaction is able to continue to completion.

I'm not by any means an expert, just playing devils advocate. Seems silicone (unjustly) has been getting a bad rap in a lot of threads lately.

Edit: Please see the wiki on Silicones for a list of its uses, many including high temp food contact.
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Old 01-18-2011, 12:59 PM   #18
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Follow Kals link on www.theelectricbrewery.com and order the FDA approved silicone that is linked to McMaster Carr.
I can't find where he links to this. The only link I can find is for sealing the volt and amp meters with general silicone.
http://www.theelectricbrewery.com/control-panel-part-1?page=11
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Old 01-18-2011, 08:07 PM   #19
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The risk of what?

You are correct, silanes can be pre-cursors to silicones. Silicone is a class of compounds, it does not refer to a specific compound. There are many silicones and many silanes. Through hydrolysis, a silane can turn into a silicone, realeasing acetic acid. I ingest acetic acid all the time. Since the acetic acid is released as a gas and removed from the environment of the reaction, and there is an unlimited supply of water vapor(a reactant) in the air, the reaction is able to continue to completion.

I'm not by any means an expert, just playing devils advocate. Seems silicone (unjustly) has been getting a bad rap in a lot of threads lately.

Edit: Please see the wiki on Silicones for a list of its uses, many including high temp food contact.
There are risks involved if the Ethyltriacetoxysilane and Methyltriacetoxysilane aren't fully hydrolyzed, but as they hydrolyze quickly, the risks are low.

After reviewing the 21CFR177.2600 of the Code of Federal Regulations, I believe it's safe to repeatedly use FDA approved silicones on food contact surfaces, though interestingly enough, you can't make baby bottle nipples from these chemicals (see paragraph h).

I'm simply concerned that a lot of people on here are using non-FDA approved silicone sealants which may have a much higher degree of risk. I think this is a valuable discussion to have, and I'm not down on the use of silicone in brewing, in general.
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