>The particular gum used might also
>respond differently at different nms, etc. In fact differences of glass
>could also account for other unexplained differences...
I think the particular gum would matter little or none. In fact, all of the
colloids (gum, gelatin, fish glue,etc.) respond in a remarkably similar way
to UV light, although the different ways they are used in practice may
suggest otherwise.
>
>However, the variables being infinite (little as I know on the topic I do
>know different colors & pigments respond differently to UV, as shown in
>their different fading & exposure times)
Absolutely. With colloid photography blue pigments give more contrast and
less speed than yellow/orange pigments.
Sandy King
>> Relative speeds for Platinum and Palladium change as the out put goes
>>from 350 to
>> 320 with platinum being slightly faster. However, the big difference is
>>in the
>> speed in relationship to Rh. If you print at High Rh, 60 to 70%
>>palladium is much
>> faster, and conversely platinum prints faster at low Rh 15% to 25%.
>>
>> So , can you see why I can not say that "the" curve can be substantially
>>effected
>> by the change in glass? It would depend on what coating solution one
>>uses and at
>> what Rh range is used. What we can see however, is that more UV rays
>>reach the
>> sensitized paper with Starphire than with Standard glass and that the
>>additional
>> UV energy will increase the exposure that the paper receives.
>>
>>
>> I don't know the sensitivities curves for the different mediums covered
>>on this
>> list, so I can't say that other processes would benefit from a change to
>> Starphire. I would guess that some would benefit from the unused UV
>>energy that
>> standard glass block out, but it may not be enough or have side effects
>>that are
>> not desired, as those you have spoken about. One should research the
>>glass, UV
>> light output of their unit, and sensitivities of materials used before
>>buying into
>> a system as best, better, the ultimate answer.
>>
>> And what the heck, I have not seen much information on the B-270 that
>>David shared
>> with us. I can see that Starphire allows approximately 70% at 325nm or
>>nearly
>> twice as much as B-270 which would lead me to not use it, or perhaps not
>>buy it.
>> I might use it if I had a sheet to see what it can do.
>>
>> Cheers
>>
>> best guesses from EJ Neilsen
>>
>> --
>> Eric J. Neilsen
>> 4101 Commerce Street, Suite #9
>> Dallas, TX 75226
>> 214-827-8301
>> http://home.att.net/~e.neilsen
>>
>>
>>
>>
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