ethan's articles

[FALKEN]

Fiberglass covered with muslin or similar should be fine. If you want to put plastic over it I suggest the white 3M painter's film, the stuff that comes on a roll in various widths. It's very thin so it doesn't reflect as much energy as visqueen would.

ok so I now have a crapton of this stuff in my garage as of yesterday. the side of the box reads "may be carcinogenic" and the smell is sort of woody. its funky. So I am going to spray glue onto them and cover with this painter's film, before I wrap in fabric. Since the rooms I am treating are tile (more diffusion would be better) I think this will be fine. I think that the curtains and also the fabric on the panels should be able to pick up a lot of the high frequencies that the film will repel.

 

[RICK FITZPATRICK]

Falken, I'm no expert, but I think if you spray glue, it may reduce the effectiveness of the material, as you not only close off the "interstices" to an extent, but you also make a rigid surface, which now will reflect higher frequencies. In fact, that is the point of using OC 705 instead of OC 703 in certain instances. Maybe Ethan can chime in on this. Actually, as these type of absorbers use friction(resistance to air molecule movement)as the principle behind absorption, I've often wondered how 705 can absorb with a foil face on it. I'll check the higher frequency absorption coefficients of 705 compared to 703.
Exactly what material did you purchase. From my understanding(Rod), there is nothing to worry about with fiberglass, but other materials may have issues. Especially since there is a warning on the box I was under the impression ALL mineral insulation products had no issues with health. I'm glad you told us.
fitZ

 

[Ethan Winer]

Guys,

> Maybe Ethan can chime in on this ... I've often wondered how 705 can absorb with a foil face on it. <

The short answer: FRK does reflect mid and high frequencies, but lows pass right through it into the fiberglass behind. Therefore, you can put thin plastic over rigid fiberglass for bass traps, but not for mid/high frequency absorbers. For the latter simply add a layer of 1/4 inch thick cotton batting under the fabric.

Also, that "may be carcinogenic" is surely just a technicality insisted on by lawyers. I'm quite sure that rigid spun fiberglass is no more carcinogenic than the same glass used to make drinking cups. Remember the huge deal with all the lawsuits over health problems "caused by" silicon implants? Years later, after Dow Corning paid out $6 BILLION in damages, it was proven beyond doubt that those implants were not a factor. But that scared the crap out of the corporate types, and set a new precedent for printed warnings.

--Ethan

 

[scrubs]

Also, that "may be carcinogenic" is surely just a technicality insisted on by lawyers. I'm quite sure that rigid spun fiberglass is no more carcinogenic than the same glass used to make drinking cups.

Well, it's not quite that simple, but you're probably right. Glass fibers are small enough to be inhaled and can get pretty far down into your airways (unlike a drinking glass). These particles get trapped in the lung and may cause local irritation. There may some incidence of chronic lung disease in persons working in occupations where fiberglass exposure is prominent (similar to that experienced in asbestos workers and those who work around silica dust). Studies seem to indicate that the risk of malignancy is low, if any (unlike asbestos fibers). However, if the product has been treated with any chemical (e.g. formaldehyde, which is a carcinogen), there may be increased risk of chemical irritation and malignancy.