Treating foam speaker surrounds

Does anyone know of a way to "treat" foam speaker surrounds to keep them from crumbling into dust ? While i know that all foam surrounds will decay over time, my prime concern right now are the woofers that i have mounted in the back deck of my car. Due to the extreme heat and sunlight beating down on them, i know that they won't last long in there. I am looking for "proven" methods as i don't want to do further damage or speed up the "rotting" process.

I've had two 8's and a 12" in there for about two years now and the 12" is starting to look "funky" in terms of discolouration but is still solid. Seeing that i have to remove the back window to replace them, i would like to be able to preserve these as long as possible. Any ideas or suggestions ? If you don't know for sure that what you mention is a valid approach, PLEASE state so in your post. I don't want to be anyone's "guinea pig" : ) Sean

PS... I'm sure that others with older speakers ( home or car audio ) would LOVE to hear about something like this also.
Sean, I have used car interior treating products such as Armorall on HOME speaker foams with good results -- as far as I can tell. The foams look as new and still feel springy. I do it regularly on an old speaker pair and, particularly during dry season, the material seems to absorb the product in no time. I avoid treatment when the room is very hot
Pls remember however, this is at home where "living conditions" are more controlled than the back window of your car! Cheers
I have used 3m Scotchguard on my foam surrounds on a pair of home speakers for about 5 years or so with good results-no rot yet and I live in rather high humidity. I have heard of others putting foot powder on the surrounds because they believe it is some sort of bacteria that eats up the foam. Caveat, I have never tried this.

A better solution might be to tint your windows with a metallic type of tint that reduces heat and blocks out uv light. You could also try putting a screen over the speakers (like a grill) to further block out heat. My friend's Mercedes has this type of screen (retractable) that you can actually see through, yet blocks out heat and light.
Stereophile has had an ongoing debate in the "tweaks" column (back inner page - now no loger running) for the past year or so on the use of ArmorAll and other treatments... all I can remember is that ArmorAll was determined to be a no-no, but very similar products existed that didn't cause any damage or chemical/physical modification to the surrounds. If you're a subscriber, check out the tweaks column dating back a year or so. If not, I can look these up and give you a more complete lowdown at some point.
Hi Sean:

Seems to me it's like spraying something on a rose to keep it blooming forever. Nice idea but maybe can't be done. You don't want to change the suspension of the cone either.

"An once of prevention is worth....." Kind of pedestrian and i'm sure you have thought about it but park in the shade whenever possible to avoid heat and crack the windows and cover the cones so no sunlight hits them. No reason to leave the surrounds exposed to sunlight.

Also, some things that might work great to preserve surrounds indoors or from heat might be terrible if sun (ultraviolet ect) is added to the mix. Might be a big difference what works well inside and what works under a rear window. Sunlight is murder.

I remain,
Sean, as a former chemist, I would recommed you contact a foam company. You could try Foamex. You want a company that makes it, not who fabricates it.

Try to bypass as many of the company's "suits" as possible. Ultimately, you want to get in contact with either an R & D, or a formulations chemist(very often, one and the same). They almost never get calls from the "real world", but are ecstatic when it happens. And, they are basically the only people in the company who have ANY knowledge of the product. How to make it, how to break it, how to make it last longer.

Just try to get past the receptionist, and have her route you in the right direction. If all else fails, just start dialing company extensions, and explain what you want. You are looking to talk to a foam chemist.

From my perspective, I would think the ultimate goal would be to find out what high boiling solvent is used in this type of formulation. You probably have polyether or polyurethane foam. The person on the other would know better than I. They would also let you know what should be applied.

Normally, you would want the same high boiling solvent as was used as the foam's plasticizer. A plasticizer is a high boiling solvent that keeps a polymer(the foam in this case), soft, pliable, flexible, sticky, etc. Otherwise, it would hard, brittle, and fall apart. The extremely high boiling point of the plasticizer ensures that the polymer keeps itself in good condition over the course of years.

However, it is a liquid. And, does evaporate, however slow. Eventually, it dissipates to the point where the polymer may crack(as in light fixtures), deteriorate, or just fall apart. Obviously, the extreme heat in a car interior makes this happen faster.

The general rule of thumb is that for every rise in temperature of 10 degrees Centigrade, reaction rate doubles. So, take it from there.

Plasticizers are usually phthalate(pronounced thal - ate) based compounds. For example, dibutyl phthalate, butyl benzyl phthalate, texanol benzyl phthalate, etc.

You also should add a bit of UV protection. UV does A LOT of damage.

Sorry to ramble on...

Anyway, be friendly to the guy. Don't BS him. Make him understand really quickly that you are not a salesman trying to have him try something. Ask for his honest advice. And, if you find good result, ask him to provide you with a 1 or 2 ounce jar of what he recommends. In my case, I would definitely provide it for someone in your situation. Just be sure to explain that you are a mature adult, and will not use the product in a means that will get yourself, or more importantly, him, in any kind of trouble.

If he is of help for the compound, but not in providing it, let me know. I can point you in another direction.