Using Latex Cement for KLH Cloth Surround Doping
- Thread starter KingBubba
- Start date
For those interested this is what I use.
http://www.amazon.com/Black-PTI-Butyl-Rubber-Sealant/dp/B001G0XT38/ref=pd_cp_hi_0
Read through the description, and you'll see it is very durable, and highly flexible. Like I said toluene is readily available, but in my opinion most thinners will work as they serve no other purpose than to thin the rubber for application, and then evaporate leaving behind the butyl coating. I've got a whole damn mason jar of the stuff, so my offer still stands.
Edit: Also the 12.5 drivers that are mentioned I believe refer to the mids in the model 5 and 12.
What else is in that product other than butyl rubber?
Hopefully Roy C will see this thread and chime in. It would be great if he could tell us where he sourced the butyl for the version he developed (which is the same one sold by Larry at VintageAR on ebay.
Speak of the devil. Roy posted as I was writing mine.
Roy, can you post your recipe and source(s)...or it the information proprietary? Thanks!!
BBRN
Well-Known Member
vinylisfinal
Super Member
aviation permatex thinned with denatured alcohol works perfect. stays tacky is not heavy and will not ruin the surrounds at all. i have used it on over 100 woofers and tweeters.
Thanks. I wonder if the calcium carbonate, silica and talc add more weight or have any other effect which is undesirable.
BBRN
Well-Known Member
^ while I've only got a couple basic organic chemistry classes under my belt, I wouldn't think so. They most likely add to its durability, flexibility, UV, and weather resistance. Keep in mind this stuff is going on really thin, just enough to soak in and coat the fibers of the surround.
Thanks! I've used Roy's concoction on a number of KLH and AR drivers over the past 3-4 years, and am very pleased with its performance to date. I know that he and his colleagues tested a variety of compounds, including some version(s) of permatex. If I remember correctly, they found a problem with it...but I don't remember what it was. Hopefully he can provide more info.
With some input from Classic Speaker Pages forum members (co-authors of the AR-3a restoration guide, one of whom consulted with Roy Allison) the basic formula was figured out. At first we thought Permatex gasket sealant was close enough, and we unfortunately included the recommendation in the guide. We later found through measurements it could reduce compliance over a matter of months, especially when applied too heavily.
I found the primary butyl ingredient was impossible to acquire in small quantities, and difficult to work with. Toluene was the easiest part, but it is volatile and generally nasty stuff...and rather high heat is involved in making the compound, which makes it even worse. After much experimentation, measurements, etc, and lots of spent dollars and brain cells, I ended up with about a gallon of the stuff. A number of AK and CSP forum members benefited from the endeavor, and Larry/"Vintage AR" ultimately purchased it, along with the formula.
Even if I could share the details, it is doubtful it would be worth the expense and trouble to make given the cost of the minimum quantity of the required raw compound...unless someone intends to go into business. With that said, I can tell you that Larry's cost for materials, bottles, etc, along with the manufacturing procedure are very high, which of course is reflected in his price.
Once again...This compound is meant to be a re-sealant, so it is likely thinner than the original sealant. The distinguishing characteristic compared to caulks, rubber cements, etc, is that it does not "dry" even when the carrier solvent, toluene, has evaporated. It does not form a membrane, so the degree of flexibility is not an issue. It is very sticky out of the bottle, and remains tacky. (It is actually much the same as the sticky compound found on some tweeter domes.) The high concentration of toluene serves to soften the old sealant, and allows it to combine with the new. The goal is to add as little mass as possible, and to retain the very compliant nature of the original acoustic suspension cloth surround. (It should be noted that "white" water based compounds sold for treating non-acoustic suspension woofers are not appropriate for this purpose.)
I should mention it was never my intention to hawk this stuff. I was just concerned about the number of old woofers I was seeing with compromised performance due to surrounds coated with non-removable glues, caulks, and even "varnish"! Attached is a photo of an early AR-3a woofer I recently received for repair. It was coated with one of the white "treatments" currently sold by some foam surround sellers. Fs now measures 35hz. It is supposed to be 18hz or less. The surround will need to be replaced with foam.
Roy
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That's good to know. Thanks
KingBubba
"Too Much Stuff"
Aside from attached references and finding Vintage-AR on vacation; I am left being just as confused as I was following two days of research. I now understand that rubber cement is latex, not butyl and is therefore not appropriate. Having purchased the Permatex tacky gasket product following what I have read regarding RoyC's research and then today finding that it was later found to stiffen enough to change the cone movement after some time; I am bound to buy some of the Vintage-AR's product, if any remains. A question I still have is whether it is necessary to coat the dust cap. The dust caps still feel tacky and are not soft and porous like the surrounds, "skivers", are.
Airplane dope is designed to add stiffness to the canvas and is almost the same process as is used in theatrical scenery making and preparing an artists canvass to paint on. All of this "sizing" is there to add stiffness to the surface and shrink the canvass to tighten it. This type of dope is usually nothing more than Elmer's white glue that is thinned with water. This would be inappropriate for use on surrounds.
I had no idea, in the beginning of this trip that it would become so complicated. I appreciate all the help here and still welcome any further thought or opinions regarding this process. Thanks to all. :thmbsp:
Airplane dope is designed to add stiffness to the canvas and is almost the same process as is used in theatrical scenery making and preparing an artists canvass to paint on. All of this "sizing" is there to add stiffness to the surface and shrink the canvass to tighten it. This type of dope is usually nothing more than Elmer's white glue that is thinned with water. This would be inappropriate for use on surrounds.
I had no idea, in the beginning of this trip that it would become so complicated. I appreciate all the help here and still welcome any further thought or opinions regarding this process. Thanks to all. :thmbsp:
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I find this thread somewhat disturbing! Suddenly some people want to make their own sealant, and share with others versus buying a small jar for $15, shipped no less, coating your woofs, and moving on. The product simply does what it needs to do, albeit in a small purchased amount. Two weeks ago I got my second bottle to redo some 6s, and still have enough between the two bottle I believe to do another pair of 4Xs.
However, the tone of this thread is tacky! My 2 cents!
However, the tone of this thread is tacky!
My 2 cents!
GD70
Lunatic Member
The dust covers should also be sealed. There was a KLH factory service bulletin that stated all speakers in for repairs were to be resealed, both the surrounds and dust caps.
When the stuff is available from vintage-ar, get it and be done.
Glenn
I find this thread somewhat disturbing! Suddenly some people want to make their own sealant, and share with others versus buying a small jar for $15, shipped no less, coating your woofs, and moving on. The product simply does what it needs to do, albeit in a small purchased amount. Two weeks ago I got my second bottle to redo some 6s, and still have enough between the two bottle I believe to do another pair of 4Xs.
However, the tone of this thread is tacky!
Sorry if I have offended your sensibilities. You may have no interest in producing your own sealant, but I do. The fact that you aren't interested in doing so doesn't disturb me....not sure why the fact that I would like to know more about doing it is disturbing to you?
I restore vintage speakers as a "hobby business", using the proceeds to fund my own audio acquisitions. I do enough of them to make the cost of the VintageAR product a significant issue. If it would be possible to make my own without undue effort or fixed costs, it would make sense to do so. In any case, you can ease your mind....given the info that Roy provided, I will not be doing so.
On a related note....I find it terribly disturbing when someone prefers to replace their own foam surrounds rather than paying me to do it, or replace their own grill cloth rather paying me to do it, or build their own speaker stands rather than paying me to do it. :yes:
BBRN
Well-Known Member
I find this thread somewhat disturbing! Suddenly some people want to make their own sealant, and share with others versus buying a small jar for $15, shipped no less, coating your woofs, and moving on. The product simply does what it needs to do, albeit in a small purchased amount. Two weeks ago I got my second bottle to redo some 6s, and still have enough between the two bottle I believe to do another pair of 4Xs.
However, the tone of this thread is tacky!
Disturbing? Geez. I find it funny how so many feathers get ruffled around here sometimes. Relax folks! Yes, I made my own sealant before I knew vintage AR existed. I did some proper research and found the service bulletin from KLH. Its butyl rubber thinned and used as a coating. I shared said information. It works fantastic, and is probably very close maybe even better than what was originally used. God forbid someone finds a DIY idea that works, who isn't trying to make a profit from others. We wouldn't want that behavior here on AK. As I said before, I have nothing to gain, unlike others...just trying to be helpful...really. I can at least guarantee its better than 99.9% of other threads recommending various things that should definitely not be used. Sorry if anyone is offended or disturbed...I'll go punish myself now
I am quite confident Vintage-AR just experimented and over time came up with his own recipe based on available chemicals. He doesn't have a 55 gallon drum of some original liquid. If someone came out with a successful alternative I bet the price would come down.