Longevity of foam tape for ESL spacers?

[CharlieM]

I use 3M urethane foam tape for the spacers in my ESL's and I'm just curious about the tape's longevity. I rebuilt my panels after 30 months to upgrade the stator and diaphragm coatings and the foam tape appeared to be still in good shape (still elastic and tacky) when I dismantled the panels.

Has anyone verified how long 3M foam tape will last? Or, has anyone experienced tape failure due to aging?

[CharlieM]

OK... I should ask the question in a different manner:

For those who've built ESL's using 3M foam tape, how long have your speakers been in service?

For my speakers, the answer is 30 months.

[Andersonix]

Doesn't ML use something like this (foam tape spacers)? I think my SL3 panels' tape at 10.5 years old is loosening up and letting the stators get too excited sometimes. I'll be satisfied to get 15 years from my panels, at which time the coating is shot anyway?

[CharlieM]

Originally Posted by Tosh

Doesn't ML use something like this (foam tape spacers)? I think my SL3 panels' tape at 10.5 years old is loosening up and letting the stators get too excited sometimes. I'll be satisfied to get 15 years from my panels, at which time the coating is shot anyway?

The ML's I've seen use a clear plastic for the horizontal spacers. I don't know what material is used for the edge spacers.

[CharlieM]

Originally Posted by Tosh

Doesn't ML use something like this (foam tape spacers)? I think my SL3 panels' tape at 10.5 years old is loosening up and letting the stators get too excited sometimes. I'll be satisfied to get 15 years from my panels, at which time the coating is shot anyway?

The ML's I've seen use a clear plastic for the horizontal spacers. I don't know what material is used for the edge spacers.

[bolserst]

Originally Posted by CharlieM

OK... I should ask the question in a different manner:

For those who've built ESL's using 3M foam tape, how long have your speakers been in service?

For my speakers, the answer is 30 months.

Years ago I called 3M's technical support line concerning the life expectancy of their 4000 series of double sided foam tape. I was told 25 years. I was also told that the white foam would yellow with exposure to UV, but this had no affect on its mechanical or electrical properties. I also asked if exposure to ozone would degrade the foam and was told no. Another thing that was mentioned is that for strongest bonds, the tape should be used within 2 years of manufacture. So, probably best to get your tape from a high volume dealer.

My oldest ESLs built using the 4000 series 3M tape, that have been in regular use, are now 14 years old.

[alexberg]

That's a good thing to know.
An alternative would of been white/transparent silicone rubber for spacers.
For one it's darn expensive... but soft and would not create, as Calvin mentioned, stress concentrator like Plexiglass/rigid plastic spacers would do.
From the other hand, MMM tape is not cheap either.
Alex
Just checked McMaster silicone strip 1/16x3/4x36" has a tag of $2.77
Urethane tape is $14 for 5'

[CharlieM]

Great info Bolserst! The foam tape is about as easy as it gets and now I don't see any compelling reason to use anything less easy.

[jeneses]

Hi CharleiM,

I am about to build my first panels following your gide and other instructions.
Would you share some info on the upgerade you carried out?

Regards
Thomas

[CharlieM]

Hi Thomas,

After 30 months of trouble free service, I rebuilt my electrostat panels a couple of months ago primarily to replace an unruly stator sheet that was bent ("oil canned") from day-one and I never was able to get it as flat as I wanted it and that always bothered me. Also, some months back, my friend Mavric and I tried out some new coatings and insulating tricks which worked well in his ESL project and I wanted to incorporate those improvements into my speakers as well.

My new panels use an automotive 2-part polyurethane stator coating, improved tape insulation to prevent arcing along the critical stator edges and a new diaphragm coating that's crystal clear and unaffected by changes in humidity. My blog page has been updated to include all of these improvements. So, good luck with your project and keep us posted-- Enjoy!
Charlie