by archive » Sun Apr 11, 2004 5:17 am
From: SRF7@x??x.xxx
Date: Fri Dec 17, 1999 1:41 am
Subject: Re: Any guesses?
In a message dated 12/15/99 7:34:58 PM Eastern Standard Time,
cactusfire@c... writes:
<< Yes, I should have mentioned, it's not old-style plaster, it's
Structolite, a
perlite aggregate gypsum plaster. It's several coats, thickness ranging from
3/8" to 1/2", with a finish texture similar to stucco.
>>
How fine grained is it? Considering:
MATERIAL SABINS/Sq FOOT AT (Hz) 125 250 500 1k 2k 4k
Avg.
CINDER BLOCK, UNPAINTED 36 44 31 29 29
25 0.32
CINDER BLOCK, PAINTED 10 5 6 7 9
8 0.08
GYPSUM BOARD, 1/2 INCH 29 10 5 4 7
4 0.10
I would think the number of little holes in the grain (interstices) makes a
big difference on the HF stuff ... enough to perhaps base your judgment of
the probable outcome primarily on this factor taking into account that since
the plaster is on a panel of gyp board and therefore able to vibrate a bit
that there will be some low freq. absorption either way
Scott R. Foster