[Darkroom] Granite Counters

Arlen Abraham arlen.abraham at gmail.com
Sat Feb 6 13:25:08 PST 2010


I've got a Geiger counter. It's not calibrated but hey, it'd be fun.

--a

On Sat, Feb 6, 2010 at 10:58, Chris Murphy <chrisnoisebridge at gmail.com> wrote:
> This is just a guess, granite is nowhere near radioactive enough to be
> a concern around film. The exposure time with direct contact to
> granite would probably be months with high speed film. Again, I'm just
> guessing.
>
> As a boy, I measured the radioactivity of granite buildings and found
> no significant levels above cosmic and solar background radiation.
> Smoke detectors contained americanium and were much more interesting
> to measure.
>
> Apparently old lenses contain thorium and yttrium and even those would
> take several weeks to expose ISO 100 film.
>
> We could intentionally expose ISO 6400 film to granite in a light
> tight photo paper box and see what happens vs a clipping of the same
> roll that has not been exposed. A Geiger counter could be used to
> calculate a proper exposure time?
>
> Chris
>
> Sent from my iPhone
>
> On Feb 5, 2010, at 16:30, Jasmine Strong <jasmine at electronpusher.org>
> wrote:
>
>>
>> I'd be touchy about granite for a darkroom on the grounds that it can
>> be surprisingly radioactive and that this can fog film over time.
>>
>> -J.
>>
>> On Feb 5, 2010, at 3:46 PM, John Magolske wrote:
>>
>>> * Kelly <hurtstotouchfire at gmail.com> [100205 15:37]:
>>>> Well, just to be clear on our options here, what are our
>>>> requirements
>>>> for a counter surface?  (Ben?)  What are our other price options?
>>>>
>>>> -Stainless steel (also not cheap)
>>>> -Formica (cheapest option--price estimate?)
>>>
>>> I've heard soapstone is ideal for chem-lab counter tops (more inert
>>> than granite, etc.). I'm not suggesting we should hold out for that,
>>> but if there happens to be a big slab of it laying around
>>> somewhere...
>>> It's also easy to cut.
>>>
>>> John
>>>
>>>
>>> --
>>> John Magolske
>>> http://B79.net/contact
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>>
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