RE: red safe light

Yes, that was my impression also. I did some work with salted paper a
few years ago and worked in a room with a 100 watt yellow bug ligh,t
as I do with other alternative processes, and did not get any fogging
from the light.

Sandy

>DEAR LIST,
> All along I thought that salt prints were only sensitive to UV so ANY
>source that had the UV filtered out was fine. I believe that is what Ryuji
>is saying...yes? Am I wrong here? So why the red safe lights?
> CHEERS!
> BOB
>
> Please check my website: http://www.bobkiss.com/
>
>-----Original Message-----
>From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
>Sent: Thursday, November 10, 2005 5:29 AM
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: red safe light
>
>Ryuji,
>
>assuming we are talking of a UV safe light, any color above the UV range
>would theorically work. In reality, most of the materials used to filter out
>the UV or any other range of the spectrum, are far from perfect and
>especially they don't usually have a sharp cutoff in desired range. You can
>visualise this a bit like a graduated filter and the darkest area would be
>placed in such a way as to block the UV range (partially) and letting most
>of the other colors or frequencies go through barely affected. A good UV
>filter would need an effect something like a 8 EV or stops maybe more in the
>UV range to work. It all depends on the sensitivity of the material your
>using.
>
>The physics of light would suggest that a red translucent material like the
>one used on the Home Depot bulb would probably have an effect on the UV
>range but maybe it wont be enough. As I said above, the dimming effect of
>this specific red material on the UV range isn't known, for example an
>infrared sensitive film (IR) also have a similar sensitivity in the blue
>range.
>
>A red filter like the Wratten #25 as only about a 10 stop blocking effect on
>the UV while a #8 (yellow K2) is blocking even more UV then that.. As you
>can see, it's more a question of the response of a material then only it's
>color.
>
>Yves
>
>
>
>
>
>
>----- Original Message -----
>From: "Ryuji Suzuki" <rs@silvergrain.org>
>To: <alt-photo-process-l@sask.usask.ca>
>Sent: Thursday, November 10, 2005 2:50 AM
>Subject: Re: red safe light
>
>
>> From: Judy Seigel <jseigel@panix.com>
>> Subject: red safe light
>> Date: Thu, 10 Nov 2005 02:38:21 -0500 (EST)
>>
>> > (I've also had fogging when my red photo bulb got scratches -- most of
>> > them are made with a red lacquer sprayed on top of a regular plain
>bulb...
>> > which can scratch, flake or crack. I patched with red nail polish.)
>>
>> Does it have to be red? What difference does it make?
>>
Received on Thu Nov 10 08:12:11 2005