Silicone Sealant and Driver Damage - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 19 Old 01-16-2007, 10:21 PM - Thread Starter
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As an attempt to settle the debate of whether or not silicone will damage your driver if you don't let it sit out enough I bring to you a couple of facts.

#1
A plastic silicone sealent has a concentration of 77.9 mg per cubic meter of VOC's (Voletile Organic Compounds, meaning they are corrosive to organic compounds) and an emission rate of 26.0 mg per square meter per hour. This is a roughly low emmission rate, but this is after it cures.

#2
I will quote this straight from the site,
Quote:


Silicone sealant (acid curing)

By monitoring the emission over time for a material, it is possible to estimate the time needed for the material to offgass until the emission rate of pollutants reaches a low enough level that the material can be considered safe.

As an example of this the emission profile for an acid curing silicone sealant (Bostik Silicone 2680) is shown below (fig. 5). The sealant was exposed in the chamber as a 0.5 m joint cast into an aluminium U-profile.


Fig. 5: Emission profile of Bostik 2680 silicone sealant over 29 days.

source: http://iaq.dk/iap/iaq2000/2000_14.htm

As can be seen acid curing silicone sealants (which I beleive is what most are) releases Acetic acid. Acitic acid is defined as follows from Wikipedia,

#3
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Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. Pure water-free acetic acid (glacial acetic acid) is a colorless hygroscopic liquid and freezes below 16.7°C (62°F) to a colourless crystalline solid. Acetic acid is corrosive, and its vapour causes an irritation to the eyes, dry and burning nose, sore throat and congestion to the lungs, although it is a weak acid based on its ability to dissociate in aqueous solutions.

Acetic acid is one of the simplest carboxylic acids (the second-simplest, next to formic acid). It is an important chemical reagent and industrial chemical that is used in the production of polyethylene terephthalate mainly used in soft drink bottles; cellulose acetate, mainly for photographic film; and polyvinyl acetate for wood glue, as well as many synthetic fibres and fabrics. In households diluted acetic acid is often used in descaling agents. In the food industry acetic acid is used under the food additive code E260 as an acidity regulator.

As they said and as I have said many times before, the gas emitted by the silicone sealant (acetic acid) is corrosive. Wikipedia goes on to explain,
Quote:


Concentrated acetic acid is corrosive and must therefore be handled with appropriate care, since it can cause skin burns, permanent eye damage, and irritation to the mucous membranes. These burns or blisters may not appear until several hours after exposure. Latex gloves offer no protection, so specially resistant gloves, such as those made of nitrile rubber, should be worn when handling the compound.


I beleive that acetic acid will easily deteriorate foam surrounds, which are still common (Dayton DVC series for instance).

If your drivers use foam surrounds let the silicone cure for 4 - 6 days

As for rubber surrounds it is pointed out that you need special rubber gloves to handle acetic acid. This would lead me to beleive that it can still deteriorate most rubbers, so One could assume that even rubber surrounds could be damaged, but most likely only weakened.

I hope this clears some things up.
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post #2 of 19 Old 01-16-2007, 10:54 PM
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Quote:
Originally Posted by Gir_1337 View Post

As an attempt to settle the debate of whether or not silicone will damage your driver if you don't let it sit out enough I bring to you a couple of facts.

#1
A plastic silicone sealent has a concentration of 77.9 mg per cubic meter of VOC's (Voletile Organic Compounds, meaning they are corrosive to organic compounds) and an emission rate of 26.0 mg per square meter h (not sure what h is). This is a roughly high emmission rate but quickly deteriorates after a few days, which brings me to...

#2
I will quote this straight from the site,
source: http://iaq.dk/iap/iaq2000/2000_14.htm

As can be seen acid curing silicone sealants (which I beleive is what most are) releases Acetic acid. Acitic acid is defined as follows from Wikipedia,

#3
As they said and as I have said many times before, the gas emitted by the silicone sealant (acetic acid) is corrosive. Wikipedia goes on to explain,



I beleive that acetic acid will easily deteriorate foam surrounds, which are still common (Dayton DVC series for instance).

If your drivers use foam surrounds let the silicone cure for 4 - 6 days

As for rubber surrounds it is pointed out that you need special rubber gloves to handle acetic acid. This would lead me to beleive that it can still deteriorate most rubbers, so One could assume that even rubber surrounds could be damaged, but most likely only weakened.

I hope this clears some things up.

Thanks for that fine dissertation on the use of silicone caulk for sealing drivers.I've probably used it for 20 years or more and never really noticed a problem ruining drivers of all types.The only nasty problem was prying the drivers out and scraping all the stuff off when changing/replacing drivers.

I'm getting ready to build a dual driver Rythmik,and I'll probably just use some foam tape.Simple and effective.
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post #3 of 19 Old 01-16-2007, 11:01 PM
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Quote:


As for rubber surrounds it is pointed out that you need special rubber gloves to handle acetic acid. This would lead me to beleive that it can still deteriorate most rubbers, so One could assume that even rubber surrounds could be damaged, but most likely only weakened.

I think you read that last quoted section incorrectly. Read it again..

Quote:


Latex gloves offer no protection, so specially resistant gloves, such as those made of nitrile rubber, should be worn when handling the compound.

Latex gloves offers no protection, but those made of nitrile rubber do. Nitrile Butadiene Rubber is for instance what TC Sounds uses for its surrounds.
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post #4 of 19 Old 01-16-2007, 11:02 PM
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Quote:


Thanks for that fine dissertation on the use of silicone caulk for sealing drivers.I've probably used it for 20 years or more and never really noticed a problem ruining drivers of all types.The only nasty problem was prying the drivers out and scraping all the stuff off when changing/replacing drivers.

I'm getting ready to build a dual driver Rythmik,and I'll probably just use some foam tape.Simple and effective.

You were using silicone sealant to seal the drivers to the cabinet?

....I thought people just used it to seal the cabinet. There is no reason to not use weatherstripping to seal the driver.
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post #5 of 19 Old 01-16-2007, 11:41 PM
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Weather stripping (foam tape) is what all CE companies have been using for years now since the elimination of the infamous Gorilla snot

Jim
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post #6 of 19 Old 01-17-2007, 08:18 AM - Thread Starter
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Latex gloves offers no protection, but those made of nitrile rubber do. Nitrile Butadiene Rubber is for instance what TC Sounds uses for its surrounds.

Then you should be fine and dandy. Many rubbers are similar to latex, which is why I pointed that out. I don't know the exact rubber they use on many drivers.
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post #7 of 19 Old 01-17-2007, 09:16 AM
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FWIW, I initially tried mounting the drivers on my sub using only the rubber gasket that came with them, but that did not result in a good seal. There were air leaks, particularly around the screw holes. I didn't want to use something with an adhesive property (such as caulk), I felt that all I really needed was some kind of thick grease to help provide a good seal. Vaseline is the first thing to come to mind, but petroleum products are known to weaken rubber. My search lead me to some plumber's grease. Some of it is petroleum based, and some is not... I found some that is silicone based (though shouldn't have the same problem as silicone caulk, since it's just silicone with no curing agents). I figure it must be safe, since it's used to dress rubber gaskets in plumbing, etc., to prevent them from leaking. Anyway, it did the trick perfectly. Just smeared a small layer on the rubber gasket before attaching the driver, both no the face that mates to the box, as well as the inner groove where the driver frame contacts the gasket.

Here is a great resource for determining compatibility between different materials (the link goes straight to what is compatible with natural rubber, but you can navigate from there). I had a really hard time finding the stuff I wanted... Home Depot had some plumber's grease, but it wasn't very specific as to what it was made of. I eventually found a small tin of plumber's grease at Lowes that specifically said 100% silicone grease.

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post #8 of 19 Old 01-17-2007, 09:22 AM
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Quote:
Originally Posted by Gir_1337 View Post

Then you should be fine and dandy. Many rubbers are similar to latex, which is why I pointed that out. I don't know the exact rubber they use on many drivers.

I don't use silicone sealant, I was just saying.
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post #9 of 19 Old 01-17-2007, 09:30 AM - Thread Starter
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I don't use silicone sealant, I was just saying.

Gotcha
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post #10 of 19 Old 01-17-2007, 05:26 PM
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Thanks for the info, but now what will I use for sealing inside corners of enclosures? I thought I read in the speaker building books that you are supposed to use 100% silicone so the drivers would not be damaged? This was a while back though and things may have changed. I have used silicone caulk on the few projects I have completed and never seen any damage. These where all vented enclosures though which might make the difference sice the fumes have an escape route. So what is a good alternative that will seal as well as caulking.
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post #11 of 19 Old 01-17-2007, 05:34 PM
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Quote:
Originally Posted by JUSTIN MELHADO View Post

Thanks for the info, but now what will I use for sealing inside corners of enclosures? I thought I read in the speaker building books that you are supposed to use 100% silicone so the drivers would not be damaged? This was a while back though and things may have changed. I have used silicone caulk on the few projects I have completed and never seen any damage. These where all vented enclosures though which might make the difference sice the fumes have an escape route. So what is a good alternative that will seal as well as caulking.

What about latex-based caulk?

http://www.liquidnails.com/ViewProdu...do?productId=7
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post #12 of 19 Old 01-17-2007, 06:02 PM
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Originally Posted by Willd View Post

What about latex-based caulk?

http://www.liquidnails.com/ViewProdu...do?productId=7

I might have it backwards mabe I read never use silicone based caulk. I will have to check because my memory has never been that great since high school. Thanks, latex looks to be safe from the add.
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post #13 of 19 Old 01-17-2007, 06:03 PM
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I've used latex too. But really, I don't think it matters much as long as you let it cure several days before mounting the driver.

My dual Rythmik Servo sub project (actually quad now, need to update page)
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post #14 of 19 Old 01-17-2007, 06:24 PM
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Quote:
Originally Posted by Darin View Post

I've used latex too. But really, I don't think it matters much as long as you let it cure several days before mounting the driver.

Agreed. Even then, especially with subwoofers that use rubber surrounds, I doubt the initial release of fumes is enough to do anything.
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post #15 of 19 Old 01-17-2007, 06:29 PM - Thread Starter
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Quote:


What about latex-based caulk?

If it uses the same curing agent then it would have the same problem. I know the liquid nails glue is safe, so perhaps the caulk is safe as well. I think the caulk might use a different curring agent than sealant (there's a difference in the two, but most people end up using silicone sealant. I think silicone caulk has the same effects but not as potent).

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Thanks for the info, but now what will I use for sealing inside corners of enclosures? I thought I read in the speaker building books that you are supposed to use 100% silicone so the drivers would not be damaged? This was a while back though and things may have changed. I have used silicone caulk on the few projects I have completed and never seen any damage. These where all vented enclosures though which might make the difference sice the fumes have an escape route. So what is a good alternative that will seal as well as caulking.

Vented enclosures you don't have to worry about since the gas can escape.

Again, you may or may not see problems depending on the surround material of the driver, but I would say if you are building a sealed speaker enclosure, let it cure for a few days before mounting and sealing the drivers in place.

On another side note I would imagine it is fine to use any type of sealant on the outside to seal the driver, as majority of the gas will be emitted outwards, while only a very small portion will seep through the gaps and into the enclosure, which shouldn't be a problem.
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post #16 of 19 Old 03-27-2007, 08:36 AM
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I'm having to repair a subwoofer that an authorized subwoofer repair place didn't do right.

Where some wires come through a hole, the original silicone?(not real sure what it is) was damaged and now some air pushes through the opening around this white semi transparent rubbery goo.

With this thread about silicone sealant damagine drivers and by extention the insulation on these wires, what should I use to seal this air leak?
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post #17 of 19 Old 03-27-2007, 06:27 PM
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Latex caulk or plumbers putty have worked well for me
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post #18 of 19 Old 03-27-2007, 08:07 PM - Thread Starter
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That little wouldn't really be a problem, and most of it would go on the outside (if that's where you apply it). Wouldn't be much of a problem if you used silicone. But yeah, latex caulk or plumbers putty would work just fine. I'd pick whatever I had on hand (wood glue could even take care of the job).
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post #19 of 19 Old 03-27-2007, 10:53 PM
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You can use Neutral Cure Silicone which doesn't emit acetic acid. It's what is recommended for sealing metal roofs.

Not all hardware stores have it, but you'll find it at any of the specialist roofing suppliers, for example those that that sell roof ventilators.
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