Reassure me that 703/705 is safe...

[curtiswyant]

...when covered in airtight plastic 4mil thick.

 

[c7sus]

Are you gonna use it for a comforter or sound treatment?

How can something encapsulated in plastic harm you???

RFSB is safe as mother's milk as long as you're not huffing fat rails of it. Use common sense when you handle it. As long as it's not disturbed it's not gonna shed any fibers.

Asbestos is safe too. Until you start stirring up clouds of the shit.

In fact, a lot of old asbestos installations are just encapsulated in what amounts to glue rather than removal, because the removal causes the fibers to be released.

Besides, SARS or second-hand smoke is gonna kill you faster than a bag of RSFB in your studio.............

Can I finish my cigar now???

 

[pdlstl]

it's great with syrup and lots of butter..the real stuff, not margarine!

earl

 

[RICK FITZPATRICK]

when covered in airtight plastic 4mil thick.

Hmmmmm, thats a new one on me. How can a resistance absorber accomplish its task if the molecules of air can't reach the "interstices". Not that I'm an expert, but I was under the belief that the whole purpose of its use, was to provide a friction barrier to air particle velocity. Seems to me, the moment you put a solid barrier such as 4mil poly, you've defeated the purpose. But thats only my .02. Not fact.

fitZ

 

[guido #2]

Fitz is right. it will not absorb, it will reflect, espeacially higher freqs. Use an open weave fabric, like burlap.... and dont shake it :^}

 

[curtiswyant]

I'm under the impression that 4mil thick plastic will reflect some high frequencies but will still absorb lower frequencies. And I just bought 3 10'x25' rolls of plastic sheeting so...

 

[guido #2]

curtis
It will reflect a LOT of high freqs. Might even make things worse!
And 1" 703 doesnt do too much for low end as it is. Go check out the stats at Owens Corning: http://216.239.39.104/search?q=cach...00Series.pdf+owens+corning+703&hl=en&ie=UTF-8
Also, it is tough to get a hold of. Around here they wont sell it to you unless you are a contractor. Also, the 2" 705 is denser than 703, which means it is more efective at controlling low end than 2 inches of 703.
Look around at the "commercially available acoustic products" and youll see they use an open weave material, much like burlap. (what they use has a name, but it escapes me )
I'd hate to see you have to do things twice, in the end.

PS: the way it works is like fitz says- converts sound to heat

 

[curtiswyant]

I'm using 3" thick OC 705...the first place I called had Roxul, OC, etc, available to homeowners. It was like $.26/sqft.

 

[RICK FITZPATRICK]

Hello gentleman, excuse my manners. Welcome to the board.
Cheers
fitZ

 

[knightfly]

Gentlemen, although I hadn't tried the lightweight plastic over rigid fiberglas, John Sayers HAS - his comments were entirely positive. More air left in the sound, lower frequencies no problem.

Think of it as a lighter weight "FRK" type - for surface mount, brighter highs - inside a wall, doesn't matter much at all... Steve

 

[RICK FITZPATRICK]

Well there you have it. I've come to the conclusion the physics of acoustics is subject to change without notice I'm just glad I didn't have a chance to build my little studio yet. Tommorrows research may discover sound is imaginary. I just read that diffusion is absorption in disguise. With all due respect to expert acoustical opinion, I'm out of starter material for my woodstove and I have a stack of $25 per inch thick paper for it. No more time left for tomorrows discoverys. Now, where did I put that stack of eggcrates....hmmm, I'm sure they have somesort of hemholtz.....er...diffusion....er absorption value. Maybe poly will help it. If not, theres always the woodstove. or maybe I'll just get one of those funny jackets.... no more opinion from me....adios.

fitZ

 

[guido #2]

Hey fitZ....wait for me!

 

[TexRoadkill]

Gentlemen, although I hadn't tried the lightweight plastic over rigid fiberglas, John Sayers HAS - his comments were entirely positive. More air left in the sound, lower frequencies no problem.

Think of it as a lighter weight "FRK" type - for surface mount, brighter highs - inside a wall, doesn't matter much at all... Steve

Yeah, but 4mil? That's pretty thick. I would just wrap them with Saran wrap or something.

 

[knightfly]

I agree, and I don't remember what thickness John used other than it seemed thicker than I would have expected. I personally had considered something like those thin painter's drop cloths, I think they're like 1 mil or so... Steve

 

[c7sus]

I'm building a slot resonator right now (finally!) tuned to 250-500Hz. It's small, only about 40" x 58" with a 5-1/4" average deep cavity. Built into a 90" tall x 42" wide x 8" deep overall gobo. 4" Knauf 3/lb insul with 12oz hemp weave tight against the slats. The isulation will be able to press right up against the cloth. I'd try the 1mil painter plastic before I tried 4 mil.

I'll try it both ways. I've got a Twin here that should make those slats shake pretty well.

 

[ob]

What about garden fabric - slightly porous cloth?

 

[cellardweller]

I'm using 3" thick OC 705...the first place I called had Roxul, OC, etc, available to homeowners. It was like $.26/sqft.

Damn!!! Ship me some!!! The only place around here I've found it so far wanted $2.78 a square foot!!!

Talk about rape!!!!