[Darkroom] Granite Counters

Kelly hurtstotouchfire at gmail.com
Mon Feb 8 11:04:51 PST 2010


I'm fairly convinced that a wood counter with a sufficiently durable
epoxy will work for us, and given that it's significantly cheaper and
easier to build ourselves, I think that's what we'll be going with.

I highly doubt that this will be a normal darkroom, and I have been
actively discouraging that myself.  I guess we should put up some of
our projects on the wiki or something, because I think that at present
it's just construction info and some equipment lists.

-Kelly

On Sat, Feb 6, 2010 at 12:12 PM, Chris Murphy
<chrisnoisebridge at gmail.com> wrote:
> I was suggesting direct contact because of the weakness of the ray
> dropping to infinity over the distance of an inch or two. Gamma or
> not, I'm pretty sure it's just too weak.
>
> A more practical concern for granite is that it's heavy and expensive.
> Any old counter will work in a darkroom in my opinion. If holography
> is on the agenda, then we would need/want a more specialized optics
> table. This would be far more interesting to me than a traditional
> darkroom (as I've pretty much gone all digital).
>
> Sent from my iPhone
>
> On Feb 6, 2010, at 11:29, Jasmine Strong <jasmine at electronpusher.org>
> wrote:
>
>>
>> You'd be surprised just how radioactive some granite countertops
>> are.  Some of it can be over 200 microroentgen/hr.  That's easily
>> enough to fog sensitive films in just a few hours.  Since much of
>> the radiation comes from radium daughters, there's a hefty gamma
>> component and it doesn't even need to be in contact with the material.
>>
>> -J.
>>
>> On 6 Feb 2010, at 10:58, Chris Murphy 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
>>>>> _______________________________________________
>>>>> Darkroom mailing list
>>>>> Darkroom at lists.noisebridge.net
>>>>> https://www.noisebridge.net/mailman/listinfo/darkroom
>>>>>
>>>>
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>>
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