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Rubber Surrounds Hardening With Age
Rubber Surrounds Hardening With Age
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Old 10th January 2006, 06:40 PM   #11
Joseph Hynes is offline Joseph Hynes  Denmark
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I have a bottle of Armor-All from U.S. containing silicone, but it is not intended for car interior -- tires only.

I mentioned ArmorAll just as an example of the kind of product I'm thinking of, not a specific brand recommendation.

There is unfortunately no solid information out there about how any product performs at preserving speakers, so we are in uncharted waters.

I guess the relevant points are:
watchout: the product may slowly impregnate into the area surrounding the cone, causing ugly oil stain marks. It may also impregnate into the cone (if paper) causing an ugly stain and possibly reducing the stiffness of the cone.

I've shellacked my cones before conditioning the surrounds, and tape-masked the enclosure to prevent over-spraying and seepage. Oily stains have a way of seeping very very slowly, so you may only know you-ve oversprayer a year later.

For my next pair of speakers, I'm actually considering using clear silicone sealant sold for rimming widows -the kind that remains elastic.
I figured I would apply it with my finger into the surrounds, leaving a very thin film, and removing the excess.

Joseph
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Old 10th January 2006, 06:51 PM   #12
pinkmouse is offline pinkmouse  Europe
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Rubber Surrounds Hardening With Age
If you want liquid silicone, the cheapest way to get it is to pop into a plumbing merchants, and get a bottle of the silicone lubricant used for push fit plastic piping, it's about £1.50 for 250ml.
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Old 10th January 2006, 06:56 PM   #13
SY is offline SY  United States
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Rubber Surrounds Hardening With Age
Just a couple comments from a polymer dude:

The breakdown mechanisms are much as Joseph said. Degradation from UV, ozone, oxygen, sulfur, and just plain age are all present, but to a greater or lesser degree depending on the actual polymer. His suggestions on protecting the drivers by their environment are very sound ones.

All polymers are not created equal. They have different breakdown paths and require different sorts of solutions. Aftermarket products are not generally terribly effective- for example, silicone can make a degraded surface look better, and may even penetrate and plasticize a material, but it is absolutely transparent to oxygen. And the newly plasticized degraded material will NOT behave in the same way as the virgin material. It may be better than nothing, but... And because all base materials are different with different breakdown mechanisms and different reactivities to treatments, it is impossible to have the one magic bullet treatment that protects all materials from all insults. General statements like, "Armor All is bad" should be largely disregarded.

Unfortunately, the real solution is better surround materials technologies. What I see out there is pretty crude and unsophisticated. But cheap and well-known, which are indeed virtues.

As with a phono cartridge (which also have elastomers that degrade over time), when a surround ages, it needs to be replaced (or the driver does, sadly).
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Old 11th January 2006, 01:29 AM   #14
PB2 is offline PB2  United States
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Default Silicone spray lubricant

Thank you all for the suggestions.
This is an automotive silicone spray lubricant, the chemical composition is listed at the bottom:
http://householdproducts.nlm.nih.gov...nds&id=7007009

Somehow it's major ingredient: "Aliphatic petroleum distillate" does not sound like silicone.

Would this be an acceptable silicone preservative for these surrounds?

Pete B.
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Old 11th January 2006, 01:37 AM   #15
pinkmouse is offline pinkmouse  Europe
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Rubber Surrounds Hardening With Age
Might be worth waitng for a real chemist to comment, but that sounds like some kind of solvent and I'd be worried it would damage the surrounds even more, possibly the adhesives as well.
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Old 11th January 2006, 01:43 AM   #16
SY is offline SY  United States
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Rubber Surrounds Hardening With Age
Quote:
Originally posted by pinkmouse
Might be worth waitng for a real chemist to comment, but that sounds like some kind of solvent and I'd be worried it would damage the surrounds even more, possibly the adhesives as well.

Bingo. It's just the solvent carrier for the active ingredient.
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Old 11th January 2006, 02:11 AM   #17
Joseph Hynes is offline Joseph Hynes  Denmark
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Then you'd need something that can form a flexible film on the rubber surround. And remain stable and flexible for many years.

Such a substance may well exist somewhere in the chemical and rubber industries, except that it's not jumping out at us at the consumer level.

Joseph
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Old 11th January 2006, 12:36 PM   #18
capslock is offline capslock  Europe
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Quote:
Originally posted by PB2
I'd like to ask, if you don't mind what brand drivers those are with surrounds that cracked. I'll try to find out what type of rubber was used.

I have mentioned this in another thread here: I bought a pair of Seas 17 cm woofers with the milky translucent cones on ebay which probably date from the late 80s, early 90s. Surrounds are absolutely shot, brownish, glazy surface, deep pores and an fs around 100 Hz. The might be from natural rubber from DKM (Dr. Kurt Müller of Krefeld) as most European drivers of the time. I will have to check if they bear the typical SR... type number.

Other than that, I only have a few Peerless CSX and Vifa XT18 drivers with slightly hardened and brownish surfaces bought off ebay in the case of the Peerless and from an OEM designer who had had them for a couple of months in the case of the Vifas. In both cases, the degradation was only superficial and could be removed with alcohol and glycerine.
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Old 11th January 2006, 01:26 PM   #19
The golden mean is offline The golden mean  Sweden
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Glycerine is said to reduce down rubber! I think using breaking fluid for cars is a better option. This liquide contains precerving agents for rubber,as there are many rubber gaskets in the hydralic breaking system of a car. Silicone based stuff may help if we are talking vinyl rubber(don´t know if it´s called so in English).

In every case, please be very careful and apply only small amounts. E.g. silicone shouldn´t be able to enter contacts , because of its insulating properties
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Old 11th January 2006, 07:23 PM   #20
Joseph Hynes is offline Joseph Hynes  Denmark
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As a kid, Back in the 1980's, I would carry home old TV sets thrown in the garbage and take them apart. Many of these had manufacturing dates in the 1940's.

It was a certainty that the speakers outlived the sets they were in. Some of the speakers I recovered were large 25-30 cm round and oval drivers, preserved in excellent condition, behind well-made grilles of woven fabric. The cones (of paper) were impeccable, and the edge suspension, made of rolled cloth impregnated with some shiny tar, were unaffected by many years of use. It gave me the impression that speakers last forever.

Ok, the response didn't go lower than 120Hz, but at least they didn't age as poorly as some of today's products.

Seems I was not the only one to notice that speakers last forever (if well made) Manufacturers found this a serious drawback.

Moral of the story:
Don't buy used speakers that are more than 10 years old, or, better yet, don't buy used speakers at all!

For the owner of a decaying speaker, the temptation to sell it on Ebay instead of throwing it away is enormous. He has payed good money for it, and is very distressed at the thought of junking it. It's his baby. He's grown up with it. Junking it is too painful. No, we must find a loving home for this gem...

Joseph
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