Re: Another VanDyke question

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From: clay (wcharmon@wt.net)
Date: 02/06/02-08:10:38 AM Z

Sandy:
The Christopher James book suggests adding dichromate to the wash water to
increase the contrast. Check out page 147-148.

Clay
----------
>From: Sandy King <sanking@clemson.edu>
>To: alt-photo-process-l@skyway.usask.ca
>Subject: Re: Another VanDyke question
>Date: Tue, Feb 5, 2002, 7:10 PM
>

>Ed,
>
>The problem is not that I can not increase contrast by adding
>potassium dichromate to the sensitizer, but that doing so causes a
>significant drop in printing speed, and a grainer look.
>
>On the other hand, with traditional kallitype (ferric oxalate) I can
>get nearly perfect control of contrast over a wide range with no
>increase in grain by varying the amount of dichromate in the
>developer from 4ml per 1000ml of developer up to 32ml per liter. This
>allows me to print negatives with density ranges varying from a lot
>of about 1.2 up to a high of 2.25 with little loss of printing speed.
>
>Sandy
>
>
>
>
>>Sandy,
>> In my limited experience, adding 1 or 2 drops of 3% potassium
>>dichromate definitely gives more contrast, though I often have more problems
>>with defects in the emulsion--I'm still trying to figure out if I'm just
>>being sloppy in preparing the sensitizer, or if it is dicey no matter what
>>you do What kind of problems have you had? What concentration is your pot.
>>dichromate? One of the best prints I made came when I used 2 drops of 3%
>>pot. dichromate on the first coat, then dryed, then used straight sensitizer
>>for the second coat. There was some mention at APIS that sodium
>>hexachloroplatinate might help increase contrast for VDB, but I haven't had
>>a chance to pursue it yet.
>>Ed Buffaloe
>>http://unblinkingeye.com
>>
>>----- Original Message -----
>>From: "Sandy King" <sanking@CLEMSON.EDU>
>>To: <alt-photo-process-l@sask.usask.ca>
>>Sent: Tuesday, February 05, 2002 10:16 AM
>>Subject: Another VanDyke question
>>
>>
>>> If someone knows of an effective way to control contrast with
>>> vandyke. My tests in adding potassium dichromate to the sensitizer
>>> before coating and/or to the developing water have all resulted in
>>> mixed results. Are there other options?
>>>
>>>
>>> Sandy King
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>
>
>--
>

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