Re: lemon juice and gum printing, other questions

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From: Christina Z. Anderson (zphoto@montana.net)
Date: 07/06/03-08:18:47 AM Z


Sandy said:>
> Acidity is an important issue. Again, in carbon printing the practice
> in former days was to add ammonium to potassium dichromate, which
> converted the solution to a chromate of much higher pH. This would
> result in less sensitivity but greater contrast. no
>
Sandy, just to clarify what you say above, because I'm not sure of the
punctuation: adding ammonia results in less sensitivity and NOT greater
contrast? Is the no for the greater contrast or just a typo?
     One other question: is just the normal ammonia at the grocery store OK
to use or do I have to get some special scientific kind of ammonia--in other
words is ammonia ammonia? My Tri-Ess catalog is packed...
Chris


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