Re: gum printing without dichromate

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FotoDave@aol.com
Date: 12/30/00-11:27:04 AM Z


Hi Birdie,

<< For the leaf photogram i placed a sheet of glass on top of the gum treated
canvas (instant coffee,water and gum), and placed the leaves on top.... It
took 6 to 8 hours of australian summer light. I did'nt produce a great
image, but the leaves were quite recognisable. >>

I might be wrong, but from your description it sounds like the ultraviolet
causing fading on the natural color of gum and also the color of coffee (a
natural dye), so you see if the image.
 
<< I tried making a similar print using prussian blue pigment instead of
coffee. I understand it is made with similar chemicals as used in cynotype
printing.... When I removed the transparency,there were uneven patches of
hardened gum. Within the hardened patches there was an image. Some parts
were hard and blue,some parts were hard and clear. I do not understand why I
got the result I did. I can only presume some process that is not usually
part of gum printing took place. >>

It seems like coffee produces better prints. It might be because prussian
blue is pretty stable and so is not affected by UV.

<< The image washed off under water. I will repeat both experiments and keep
the evidence this time.
>>

It means that the gum is not hardened. Only the "color" of the gum and/or
coffee is changed by UV exposure.

But I am interested in your further tests. I might do the same here too.

Dave S


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