Glasswool or Rockwool?

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Hi Ethan, Rod, Eric and all.

A friend of mine gave me a copy of a book about studio construction and making rooms soundproof.

The author states that rockwool is more expensive than glasswool, but it works better (between walls) he says.

I have the feeling he is wrong. Am I right or what?

[Rod Gervais]

Nope - he is not wrong.........

"Glasswool" is what you would call fiberglass... "rockwool" is thermafiber....

It's more dense than standard fiberglass insulation and thus is better for sound isolation.

Rod

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Ahah!!, but I thought glasswool was better for absorbing low freqs.

So rockwool absorbs more?

Thanks!!

[Rod Gervais]

light and fluffy - high
heavy and thick - low.......

like i always say - when you deal with low frequencies - you want mass mass and more mass...

Tis me mantra.......... :D :D :D

Rod

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That was quick Rod!

But why don't basstraps have rockwool instead of glass?

Let's make it clear, in Europe glasswool is sold by Isover. It's much less heavy as rockwool.

Glasswool is yellow, rockwool is grey. Are we talking about the same products? You call that yellow stuff fiberglass?

Peace.

[Rod Gervais]

Glasswool is yellow and very light fluffy.....right?

Rockwool (here) is browner and much thicker heavier........ Right?

Fiberglass (Glasswool - the material used in basstraps) when manufactured as a panel - tends to stay together much better than rockwool does.. rockwool tends to break up........

Glasswool is manufactured from spun glass......

Rockwool is manufactured from Loose Wool obtained from melting and then fiberizing of minerals through centrifugal processing reaching diameters of 6 +/- 2 microns with a length of 60 +/- 10 millimeters.

OK - now you tell me - are we talking about the same things?

Happy Hunting

Rod

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Originally posted by Rod Gervais:
OK - now you tell me - are we talking about the same things?

Rod

Absolutely! :D

The fiberglass comes in plates that are indeed 'stronger' than the rockwool. But it also comes on 'rolls', just like rockwool does as well.

Now the next question is: is the difference significant, or not so very?

[Rod Gervais]

Han,

you're talking apples and oranges here....

The intent of a sound isolation wall (they really aren't "soundproof") is to keep sound inside of the room....... to not let it escape. Although some of the process is absorbtion - the majority winds up being reflection.

For low frequencies this means mass.......

The intent of a trap is absorbtion..... - trap it and keep it there. And according to Eric Dessart - some of that energy is transfered through the back of the trap and decreases the isolation value of the wall behind it.

Picture, if you would - a concrete wall 12" thick.... it is an excellent source of isolation due to it's mass........ and would make a lousy bass trap because of it's reflective qualities.

What works for isolation is not what you want for a trap.

It's just that simple.

As far as the value of Rockwool for a bass trap goes....... if what was installed was the same density as the fiberglass (which i believe would require an adjustment of thickness) then i would imagine it would work as well........ however i do not know this to be a fact.

I always try to stick with that which has been tested...... but then again - tis those with imaginations greater than mine who develope and test these products in the 1st place......

Happy Hunting

Rod

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Apples and oranges?

IMO the mass is there to stop as much energy as possible and keep it in the room (or out). But what goes through must be absorbed and converted into warmth by a soft material like fiberglass, rockwool or something like that.

Although a bass trap has a very different task, the fiberglass is also there to absorb, like you say.

I know if I screw 12 plates of gypsum board to the wall, I won't need much fiberglass/rockwool behind it.

? :D

I'll be back tomorrow, it's 2.30 am here. :w:

Thanks!

[Rod Gervais]

Han,

Get a good nights sleep my friend....... ;)

Rod