Repairing crumbling foam surrounds - wonderful solution

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I have a speaker repair option for you. Never seen this done before...

I am in the middle of dusting off and restoring my 30 year old audio system and started to get to work on my old home-built speakers.

But after 30 years, the surrounds were extremely brittle and starting to crumble. I don't want to bother with reconing or replacing the surrounds without trying a little experiment....and my solution WORKS beautifully....

Step 1. Lay the speaker on its back.

Step 2. Get some FLOWABLE windshield silicone from the auto parts store.

Step 3. Squeeze the silicone right on top of the foam surround and brush it on so it "flows" completely over the top of the foam. As thinly as needed to get complete coverage. I used a small chemical brush to spread it a bit.

Let it flow as it dries. The result is a "shiny" epidermis that forms a strong and very flexible surround in the exact shape of the original.

Sound? BEAUTIFUL! No coloration. Fast. Sounds as good as I remember them when new.

I have since done this to many speakers both home and those "rattly" auto speakers. Worked every time.

Hope this helps.
I'm half tempted to try this on my foams even though they're not that old. I'd imagine it would prolong their life by quite a bit.

Wonder if it would work on fabric surrounds? I remember reading a thread where the flexible sealer had gone stiff and they were struggling to find something suitable to reseal the surrounds. I think everything they tried would stiffen up eventually.
I am confident with my solution, but I must strongly emphasize that FLOWABLE windshield silicone is the only thing to use. I have a great deal of experience with the stuff and am confident it will do a fine job for repairs. Having said that, I probably would not consider using it as a preventive to fend off decay, as the application will most certainly change the mass, stiffness or compliance of your carefully designed speakers and MAY alter the tuning of your system slightly. I would therefore use it as a last ditch intervention after you first notice tearing or crumbling. The neat thing about FLOWABLE silicone is that it is strong ,yet flexible enough to operate as a surround even if all of the foam disappears. It is not likely to tear if applied thick enough.
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