U of S | Mailing List Archive | alt-photo-process-l | Re: gum beginnings

Re: gum beginnings

On Nov 18, 2006, at 2:06 PM, Laura Valentino wrote:

One question I have is about the potassium metabisulfate (it came in a
kit, no instructions), which I had thought was a fixing agent, but turns
out is a clearing agent. Does that mean I develop the print in that
solution? What I actually did, was develop in plain water, then put it
in the clearing solution bath. The color seemed to just slide off when
I put it in the clearing bath!


The K metabisulfite (I don't think you have a sulfAte) is a clearing bath which normally may be used following drying of your final layer, however many you use. (It is not uncommon for me to do 7-8 layers on a print.) So after you have built the print color and contrast up to your desired level, the metabisufite may be used. (It is optional BTW). As Hamish indicates, the print should be dried so the upper layer hardens. That way the clearing agent will only remove the dichromate image, not the pigment image.

You may find the color shifting and saturation improving afterward and the print losing some density due to the removal of the dichromate image. If you do use the clearing agent you my wish to anticipate this shift and compensate where you can (e.g., having the print appear a bit darker and greener than you really want the final result). IME, the dichromate image is a pale green though some report it to vary into browns.

What probably happened with your first attempt is that the dichromate and an unhardened (i.e., not dried) pigment layer were both softened and removed by the clearing agent. Water is all you need to develop gum prints.

OK, gum mode off. I'm switching back to being an Ambrotypist now.