prevent hardening of speaker surrounds

Is there anything that can be applied to speaker driver surrounds that will inhibit hardening/oxidation. Even rubber surrounds will harden over time.
Armorall--if it works on auto door seals that are exposed to extreme temperatures, pressures, and UV light, it should keep butyl surrounds supple, too. OTOH I've never seen butyl surround degrade. Wouldn't a change in resonance (Fs) be more related to aging/hardening of the voice-coil spider, for which I don't think there's anything you can do....
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.
I didn't think Armor All was classified as a solvent. I thought it was classified as a protectant. I have applied it to the rubber surrounds of two of my woofers, with terrific results. Most audiophiles do seem to not like Armor All, and much of that seems based on some bogus "tweak" a few yewars back, where it was tried on CD's (in the first place, that seems idiotic to me, since polycarbonate is not a pourous plastic). Anyway, if I can borrow my brother's digital camera again, I'll photo these woofers and e-mail the photos to you, if you're interested.
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.
Well, if you are so interested in seeing this solubility table for Armor All, why aren't you asking them for it? Also, I did ask the speaker manufacturer specifically what their thoughts were before I applied Armor All, and they informed me that there would be no degradation of the rubber, and no interactions with the glue that holds the butyl rubber to the polypropylene cone. So you see, I took the only care that should have been taken, in my case. I didn't have to be a chemist to do it, either. BTW, the manufacturer is Dynaudio, and I feel that they might know a little bit more about speaker drivers (especially their own) than anyone who will ever contribute to this forum....and they have spoken.
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.
Trelja; I want to thank you for your responses. Although I am not a chemist, I did get a minor in chemistry in college. I did not like the requirement of German for chem. majors and this was the rebellious 1960's, so of course I quit chem. Although there is no occidation occuring as yet, it is inevitable. The ozone in the atmosphere will see to that - as well as UV (a good reason to keep grills on). When you buy speakers as expensive as Aerial 10ts you want to keep them around for some time and in peak operating condition. It just seemed prudent to see if there was some way of maintaining the operating parameters of the speaker surrounds as long as possible. We audiophiles seem to obsess over things like jitter, green magic markers, pucks etc. that we forget that the suspension of a speaker is probably at least as important. Thaks again. [email protected]
To clarify something, here, I agree that the suspension of the speaker is of paramount importance. However, it's the rear suspension on cone speakers (the spider, a woven fabric) where the primary burden lies, with respect to how the cone behaves, since it is connected to the "balanced center" of the moving mass of the diaphragm. The front "surround" serves primarily to keep the cone centered during motion, and serves an extremely minute roll in the "suspending" of the diaphragm's mass. Therefore, changes in sonic performance over time are due to changes/wear in the spider, and not so much from the front surround. SUBARU ALLUDES TO THIS ABOVE.
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!
While i agree with Carl that the spider is "theoretically" the most important and stressed member in the suspension of a dynamic driver, i would like to add some observations. Having several older drivers that were in excellent shape other than foam rot, i took these and had them re-foamed. Everything on the drivers remained the same ( cone, spider, etc..) and the only thing done was to replace the foam surrounds. These drivers required break in for optimum performance, just like brand new drivers. Even though the surrounds are "supposed to" have a minimal effect on their output, the bass response and several other traits were greatly improved once the speakers had been "driven" for a while. This made me re-think my stance on the importance of the surround quite a bit. I am hesitant to use any type of "conditioner" on them at this point in time unless something in the "new and improved" category pops up real soon. Sean >
As I state above, my feeling (and Dynaudio's) is that Armor All has no negative effect on a butyl rubber surround, or the glue that adheres it to the cone. I made no comment at all on its effect on a foam surround, and can only guess that it could very likely have a negative effect on foam. I also never said that the surround has "little effect on the sound", as you imply, I just said that the spider has vastly more. This assumes that the surround appears in good working order. If it is not, of course there will be a very noticeably degradation of performance. However, I never implied the contrary...If a surround can't keep the cone perfectly centered, of course there will be all sorts of bad things happening. Of course it is necessary to do whatever yopu feel is called for to maintain it, and I hope we all feel this way.
Stiffness (compliance) of a surround will partially determine the speaker's primary resonance (Fs), so it stands that altering the surround will possibly shift its resonance. It's my understanding that Armorall is a monomer dispersed in an aqueous (H2O is of course Earth's most prevalent solvent) solution, and its action is to deposit a one-molecule thick "preserving" layer on vinyl, and possibly butyl, as well. The fact that you can see it on butyl surrounds after it dries lends me to think that it's helping to seal them as it does very well on vinyl and rubber auto door seals and trim. Trouble is: how do you treat the backside?! Maybe the relative effects of spider-hardening vs surround-stiffening are shifted as a function of ratio of cone/voicecoil diameters, too: I can imagine that the quality of the surround of a 12" woofer is relatively more important than the aging of its spider, whereas the reverse might be true of a 4" midrange with a relatively stiff surround to begin with. Just conjecture, though. In the past I have run into high-tolerance voicecoil-gap drivers that scraped after a few years, probably due to spider "sagging". Running the woofer upsidedown for a while usually remedied the problem. So gravity figures in this, too!
Interesting...however, I don't see the spider as ever "hardening", I see it simply wearing out; i.e., the fabric strands develop tiny fissures that grow and become more numerous with time and wear through usage. In effect, they become "threadbare". I also agree that the effects of gravity cannot be ignored.