prevent hardening of speaker surrounds

I feel that one should be VERY careful before applying anything to butyl(or foam) surrounds. The main parameter of a liquid(i.e. a solvent) to consider here is the Kauri Butanol(KB) value. This is a very convenient measure for us audiophiles in this situation, as it is(in layman's terms) a measure of how well a solvent is able to dissolve butyl rubber. While I am not aware of the KB value of Armorall, we should be extremely careful. Damaging the surround, WILL require the poor owner to buy a new driver. And, this type of solvent could also be incredibly damaging to your speaker's finish. All this being true, I am sure there are safe products out there. They should include UV filters, as that is our enemy, along with the drying of the rubber(via evaporation - over the course of time). I would love to run this experiment on a bunch of solvents, but I am no longer working as a chemist(yes, I do miss it). But C++ programming is much more secure/better paying, so here I am. If there are any chemists in our listening audience, I would welcome the opportunity to converse with you on running this type of experiment.

Carl, as a former chemist, I have to inform you that all liquids are considered solvents. That is the position from which I am coming from. Water, is called the universal solvent(incorrectly, of course). I am not saying that Armor All would be good or bad for rubber. Just that care should be taken. Whenever I considered the usage of a polymer, I would receive product data from the manufacturer of that compound. Almost always, a solubility table is included. Showing which type of solvent(in general terms - alcohols, ethers, ketones, esters, aromatic or aliphatic hydrocarbons, etc.) a polymer is resistant to(and to what degree), and which it is not. More importantly, I would be interested in seeing the Material Safety Data Sheet(MSDS) on Armor All, which should list the components(including solvent[s]) contained. Every chemical in the USA has an MSDS, and the manufacturer is obligated to provide it to you(often available on the web these days). Otherwise, they get their pants sued off.

According to the MSDS, the primary solvent contained in Armor All is Propasol P(a glycol ether). I won't bother listing other components. This solvent should be OK for butyl surrounds or epoxy(used in many adhesives - check with your manufacturer). However, it would not be safe for use on vinyl, acrylic, many polyesters(which also are used as adhesives), ethylcellulose, nitrocellulose, certain chloro or fluouropolymers(Saran or Kynar), or polyurethane. Do not use it on foam surrounds unless the foam is a polypropylene type. And make sure of the type of adhesive used to attach your surrounds. Also, keep it off your speaker's finish at all costs. These finishes are usually polyurethane or lacquer(usually nitrocellulose) based, and will be attacked by glycol ethers. Don't ruin that furniture quality finish you paid so much for in the first place.

I agree 100%. The part we don't see(suspension) is where is much more critical. I also know that speakers with different surrounds(foam, linen, butyl, etc.) sound different. Neither point was the issue in this thread, however. Appreciate your perspectives Carl, and your compliments Mjdraper. Thanks to both of you!