Re: Gum problem(s)

I would be very thankful if you would send me a copy Martin.

Cheers.
~m

MARTINM wrote:
> ----- Original Message -----
> From: <Ender100@aol.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Wednesday, November 23, 2005 8:40 AM
> Subject: Re: Gum problem(s)
>
>
>> Just wondering if you could point me to the source for the spectra of
>> sensitivity for different alt processes?
>>
>> Thanks,
>> Mark Nelson
>
>
> Being active in a somewhat different area (www.polygrama.com) mainly,
> I don't quite feel qualified to answer your question. I assume Kosar
> would be a good starting point. "Kosar" would imply not only his book
> but both the literature he quotes from and the patents he refers to.
> By the way I scanned the whole book to my computer (resulting in a
> slightly messed up pagination). So I might be in the position to send
> out the whole thing to those interested. That would be two
> multi-paged TIF files (5.8MB and 4.6MB large)...
>
> Martin
>
>
>
>
>>
>> In a message dated 11/22/05 9:30:39 AM, martinm@SoftHome.net writes:
>>
>>
>>>
>>> ----- Original Message -----
>>> From: "Sandy King" <sanking@clemson.edu>
>>> To: <alt-photo-process-l@sask.usask.ca>
>>> Sent: Saturday, November 19, 2005 3:35 PM
>>> Subject: Re: Gum problem(s)
>>>
>>>
>>>> Dichromated colloid processes, including carbon and gum, have a
>>>> maximum peak in the near UV at about 360 nm to 370 nm, varying
>>>> slightly with pH and type of dichromate. From the peak at 360-370
>>>> nm, sensitivity falls off sharply to about 320 nm, at which point
>>>> it starts to rise to another, and much large, peak at around 200
>>>> nm, where it has its maximum sensitivity. The peak at 200 nnm is
>>>> really huge compared to the one at 360-70 nm, like Mt. Everest to
>>>> the highest peaks in the Appalachians. On the other side
>>>> sensitivity falls off very gradually in the violet and blue to
>>>> near zero at around 520 nm.
>>>
>>> I don't think that's entirely accurate for dichromated colloid
>>> systems. I guess the data you quote, apply to the absorption
>>> spectra of a dichromated water solution.
>>> When it comes to dichromated colloids, sensitivity peaks might be
>>> considerably shifted towards longer wavelengths. By the way,
>>> speaking of DCG holography (dichromated gelatin), there are lots of
>>> people to expose their DCG layer at 532nm...
>>>
>>> Martin
>>>
>>
>>
>>
>>
>>
>> Mark Nelson
>> Precision Digital Negatives
Received on Thu Nov 24 07:21:22 2005