barryg4522 Posted January 25, 2017 Report Share Posted January 25, 2017 Hi to all, does anyone know if asbestos was used on AR-2ax sn-05065 and 05070 as dampening material instead of fiberglass or wool batting? I bought a pair in beautiful condition need to open them up and would like to know if I should be concerned with this. Thanks Link to comment Share on other sites More sharing options...
ra.ra Posted January 25, 2017 Report Share Posted January 25, 2017 Those are fairly low s/n's on your 2ax's, so I suppose the stuffing could be some form of mineral wool, which preceded the use of fiberglass in AR speaker cabinets. I have encountered this material in AR-4 speakers (circa ±1964), and I simply carefully remove it, set it aside, and re-install it before closing up the cabinet. Others find it repulsive to work with or re-use, but to me it's little different from the hazards or necessary precautions needed when working with (old) fiberglass batts. To be on the safe side, it's always a good idea to wear some gloves (and mask?) when handling this material, but to my knowledge there is no evidence of this insulation containing asbestos. https://en.wikipedia.org/wiki/Mineral_wool Link to comment Share on other sites More sharing options...
barryg4522 Posted January 25, 2017 Author Report Share Posted January 25, 2017 Thank you ra.ra, I did a Google on this subject and there was some discussion (don't remember where I seen this) that asbestos was used or mixed with other batting material. Not sure of any authenticity of this but thought I would ask others. I will however take precautions when removing this material (gloves and mask) , possibly replace it. Link to comment Share on other sites More sharing options...
barryg4522 Posted January 25, 2017 Author Report Share Posted January 25, 2017 do you have experience with refinishing the cabinets. Any recommendations? Tung oil, formbys? Link to comment Share on other sites More sharing options...
genek Posted January 25, 2017 Report Share Posted January 25, 2017 Fiberglass was the original batting. There was a period during which fiberglass was in short supply and mineral wool was used instead. Mineral wool is made using almost the same process as fiberglass, but the material is more hygroscopic (water absorbant), which made the corrosion of the level control wipers worse than with fiberglass. There have never been any instances of asbestos being found in mineral wool. However, some insulation products were made by combining mineral wool with paper that contained asbestos. So mineral wool in your speakers doesn't have asbestos in it, but if you find mineral wool insulation in your house, get someone in to test it before you handle it. And whether you're working with fiberglass, mineral wool or something else, wear gloves, goggles and a face mask, because all can cause skin, eye and lung irritation. I just go buy those disposable painter's coveralls from Home Depot and suit up anytime I have to stick my hands into a speaker's batting. Because you never know what someone may have stuffed in there. Link to comment Share on other sites More sharing options...
JKent Posted January 25, 2017 Report Share Posted January 25, 2017 Welcome Barry! The AR-2ax is a really nice speaker. I recommend that anyone restoring them look at the AR-3a restoration booklet. There is a lot of info there that is applicable to your 2ax's http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/ I would disagree with ra.ra. on the stuffing. If it is rock wool, it "may" off-gas and lead to accelerated corrosion of the pots. In any case, it's nasty stuff. I suggest you go to your local home improvement store and look for small bags of fiberglass insulation. The new stuff is less itchy and it's formaldehyde-free. If I remember correctly, the small bag was about right for one AR-4x so 3 bags should do for a pair of 2ax's. If you are, or know, a fisherman, put all the fiberglass in a plastic kitchen trash bag and weigh it with a fish scale. Then you'll know exactly how much fg to use. Or maybe someone here knows. It's "about" 20 oz per speaker. http://www.homedepot.com/p/Owens-Corning-R-6-7-Unfaced-Multi-Purpose-Insulation-Roll-16-in-x-48-in-A85P/100320315 Behind the woofer is a sheet of flimsy paper called Kimpac. It's probably torn or deteriorated. It's meant to keep fiberglass out of the woofer. You can replace it with some sheer cloth, such as crinoline. Refinishing depends on the condition of your cabinets. If they're in really good shape, AR recommended applying boiled linseed oil annually. Most of us prefer Watco Danish Oil instead. If you have minor scuffs and the finish looks kind of tired, Howard Restor-a-Finish is a nice product. Just wipe on & wipe off. It comes tinted so you can select what you think looks best. Some of us like to use the Mahogany RAF on walnut speakers to give the wood a warmer look. RAF is not a finish so you will need to oil or wax over it. As I said, these are great speakers but opening them is like opening Pandora's box. The potentiometers Level controls) are notorious for corroding and making it sound like the tweeters or mids are dead. The pots "may" be something you can clean (again, see the 3a guide) or just replace them with inexpensive L-pads. And the capacitors are housed in a 50-year-old wax block. You don't have to remove that but it's a good idea to install new capacitors. None of this is difficult if you can use a soldering iron and follow directions. Ask any questions. -Kent Link to comment Share on other sites More sharing options...
genek Posted January 25, 2017 Report Share Posted January 25, 2017 The problem with mineral wool is not that it may off-gas, but that it will absorb moisture from the ambient air and raise the humidity inside the cabinet. There is only a certain amount of outgassing that can occur before the impurities that cause it are fully exhausted, but hygroscopy is a physical characteristic that never goes away. Link to comment Share on other sites More sharing options...
JKent Posted January 25, 2017 Report Share Posted January 25, 2017 3 minutes ago, genek said: The problem with mineral wool is not that it may off-gas, but that it will absorb moisture from the ambient air and raise the humidity inside the cabinet. I stand corrected. I think there's a joke here. What you want is damping but with mineral wool you get dampening Anyway--ditch the mineral wool. Link to comment Share on other sites More sharing options...
lARrybody Posted January 26, 2017 Report Share Posted January 26, 2017 2 hours ago, JKent said: Behind the woofer is a sheet of flimsy paper called Kimpac. It's probably torn or deteriorated. It's meant to keep fiberglass out of the woofer. You can replace it with some sheer cloth, such as crinoline. I have used cheese cloth to isolate the woofer from the damping material. I personally have not run into rock wool in speaker cabinets, but have seen yellow and pink fiberglass, polyester fiber filling and yes the foam sheets in Large Advents. Does anyone know when asbestos was discontinued in building and insulating materials? Link to comment Share on other sites More sharing options...
DavidR Posted January 26, 2017 Report Share Posted January 26, 2017 I was an EHS Manager for 20 years and have an EPA Contractors Asbestos license. Rock wool/mineral wool is air blown slag from iron smelting. Rock Wool, Fiberglass and Asbestos are not good to inhale. None of it. Do NOT use a vacuum cleaner. A dust mask is better than nothing but is some what useless. The best control for preventing airborne particles is amended water (soapy water) sprayed on. I'd work outdoors. Link to comment Share on other sites More sharing options...
ra.ra Posted January 26, 2017 Report Share Posted January 26, 2017 Re: asbestos in building materials, I believe it was the early 60's when the awareness of health hazards was beginning to take shape, and at that time, asbestos was a component of a great number of products used in the construction industry (floor tiles, ceiling tiles, composite wallboards, roofing cements, insulation, building felts, wall siding, roof shingles.......), and I know that this issue continued to plague manufacturers at least into the mid 80's with suits and settlements extending at least to the mid 90's. (And yes, larrybody, cheesecloth is a very good substitute for that original Kimpac.) This is by no means the beginning of a "Save-the-Rockwool" campaign , and agreed, handling this rockwool is not particularly pleasant, but when handled with care and proper precaution it should pose no severe or immediate danger. Replacing this material with new fiberglass is a good and feasible option - - - certainly an easy, inexpensive, and readily available material to substitute while you've got the cabinets opened up. Regarding theories of off-gassing and hygroscopy contributing to accelerated potentiometer corrosion, however, I'm simply not buying those notions. My reasons for re-using the original wool are: [a] there are no plans on my part to go back into these cabinets ever again (health exposure); replacement with new FG guarantees no functional improvement (performance); and [c] I'm just a cheap SOB (cost). My skepticism about the corrosion issue is based largely on personal observation and experience, as shown in this unadulterated original 50-year-old pot from an AR-4 filled with mineral wool, which exhibits almost no deterioration whatsoever. A better reason perhaps, in my opinion, for maybe not re-using the original rockwool is also evident in this pic. The wool fibers are so small that they can penetrate the small gaps in the pot enclosure, and this could possibly affect the variable control that the device is initially intended to accomplish. My pots are working fine, and once I set them, I tend to leave them alone. To the OP barryg, JKent has offered some good initial advice on the cabinets. Keep us posted on progress. Link to comment Share on other sites More sharing options...
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