John,
I added a small wedge of grey foam to square up the shape, then
weighed it.
I would also comment here that the additional black dye added to the
Crown SASS foam may also very slightly affect its acoustic
properties :-)
Vicki
On 15/07/2012, at 10:31 AM, rock_scallop wrote:
> Vicky, your math looks right. I'm curious though, with the
> irregular shape of original SASS foam, did you calculate volume
> from actual measurements or make a best guess estimate?
>
> John Hartog
> rockscallop.org
>
> --- In vickipowys
> <> wrote:
>>
>> Re the foam:
>>
>> I am puzzled, how can John Crockett's green foam be specified at 1.5
>> pounds per cubic foot, if his scrap green piece 4 x 6 x 9 inches
>> weighing 125 grams would, as a cubic foot, actually equal around 2.2
>> pounds? (if I did my maths right :-)
>>
>> John's green foam piece was approx. the same weight-for-size as my
>> grey piece.
>>
>> The original Crown SASS foam weighs the same as my grey piece.
>>
>> Rob Danielson was using 1.5 to 1.7 pounds per cubic foot density
>> foam.
>>
>> I guess it is hard to accurately weigh a small piece of foam, so
>> maybe some variations have occurred because of that.
>>
>> But if the weights of the smaller pieces was accurate, then this
>> suggests John Hartog's link to the Grainger charcoal foam of 2 pounds
>> per cubic foot would be the closest match to the original Crown SASS
>> foam.
>>
>>
>> Vicki Powys
>> Australia
>>
>>
>>
>>
>>
>>
>> John Crockett wrote:
>>
>>> BTW, my green foam, at 1.5 lbs per cubic foot density, is similar
>>> to the foam linked to on the diyboundarymic blog. So maybe it is
>>> the "right" stuff. Just not identical to what Crown is using, which
>>> may be proprietary.
>>> On 12/07/2012, at 2:08 AM, John Crockett wrote:
>>>
>>>
>>>> Hi Vicki,
>>>>
>>>> The foam I am able to find locally is green (whatever that means!).
>>>> It is called high-density foam (they also sell "regular" density,
>>>> which is white), and although the clerks in the store had no idea
>>>> about open or closed cell, it is absorbent like a sponge, so I
>>>> guess it is open-cell. It isn't nearly as dense as I expected, less
>>>> so, I think, than the foam mattress pad I mentioned. It is quite
>>>> squishy. The 4" x 6" x 9" scrap I bought weighs 125 grams.
>>>>
>>>> Could I possibly have the right thing? I can return it if I bought
>>>> the wrong material, but how can I tell? Does anyone know?
>>>>
>>>> Many thanks,
>>>>
>>>> John Crockett
>>>> Westminster, Vermont
>>>>
>>>
>> On 15/07/2012, at 6:05 AM, hartogj wrote:
>>
>>> The price $45.12 suggests the charcoal firm.
>>>
>>> I notice the charcoal firm at foamforyou.com is density is 1.5-1.7
>>> lbs./cu.ft. The grainger.com charcoal sheet that I previously
>>> linked to is 3 lbs./cu.ft. Grainger also lists 2 lbs./cu.ft
>>> charcoal sheets, and 1.45 lbs./cu.ft balls and cubes.
>>>
>>> John Hartog
>>> rockscallop.org
>>>
>>> --- In Peter Shute <pshute@>
>>> wrote:
>>>>
>>>> It works ok as http://www.foamforyou.com/charcoal_foam.htm#
>>>> Charcoal (I removed one space, hopefully the list doesn't put it
>>>> right back again).
>>>>
>>>> There are two densities of charcoal foam, and that both are listed
>>>> as suitable for noise treatment and packaging. Which one?
>>>>
>>>> Can anyone see anything on the specs page that distinguishes these
>>>> from the other foams, apart from colour? They aren't the densest.
>>>> Maybe low resilience?
>>>>
>>>> Peter Shute
>>>>
>>
>
>
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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