Adhesion to glass plates.

[wildbillbugman]

Vaughn,
I just went over my old emails from my friend who dose carbon on glass. His "secret" is a coating of 3% 250 bloom gelatin with glyoxal for crosslinking. He coats this onto the clean glass and then applies the carbon tissue.
Bill

[Vaughn]

Thanks, Bill. My comment on using the silane was half serious/half tongue-in-cheek. It is tempting to try it, but I really don't need another toxic chemical to deal with. My normal gelatin is just the softer Knox Unflavoured Gelatin -- bloom is probably closer to 100. I know PE does not like the stuff, but it makes great carbons prints for me. Would using the KUG and Potassium alum work as well as the 250 bloom and glyoxal? I have heard that the glyoxal tends to yellow (if my memory serves me right). I don't mind waiting the time it takes for the alum to do its thing.

And about the alum...I have Potassium alum, Potassium chrome alum (or Chrome alum -- can't remember which right now and I am not near my supplies). Any better to use one over the other?

Vaughn

I am assuming that I would have to use a hardener, since I will eventually be developing the glass/carbon tissue sandwich in 120F water for 15 minutes. But I still might try to transfer the carbon tissue directly onto super-cleaned glass and skip the intermeate coating step.

[wildbillbugman]

Would using the KUG and Potassium alum work as well as the 250 bloom and glyoxal? I have heard that the glyoxal tends to yellow (if my memory serves me right).

And about the alum...I have Potassium alum, Potassium chrome alum (or Chrome alum -- can't remember which right now and I am not near my supplies). Any better to use one over the other?

Vaughn

Vaughn,
Sorry Vaughn, I just don't know the answere to these questions. PE has said that, for glass only, chrome alum is perffered over glyoxal. I do not know anything about discoloration of either. My last "big idea" concerning tissue was to make a Pt/Pd tissue. Did a few experements, then let it go,probably for the best considering the cost!
Happy Tissueing,
Bill

[Photo Engineer]

I have been informed by good authority that Chrome Alum (the blue stuff!) is best for plates. It is ionic and tends to bond better with glass. I have tested Chrome Alum and CA + Glyoxal, and they work for me. The old timers used CA exclusively for everything and then to CA for plates and Glyoxal for subbed film and paper.

Glyoxal has been reported to yellow, but it was used almost exclusively in many products in the early part of the 20th century and they seem to hold up well. I have been using it for 5 years or more with no problem. However, remember that these early reports were with products that used egg albumen mixed with gelatin and also with milk. All of these changes would have to be put into the equation before making a judgment.

PE

[Vaughn]

Thanks, PE...I'll check the labels of the Alum I have in the morning and see what I got -- don't remember any of it being blue, though! Some of it will be 30+ years old.

Bill -- the price of platinum is dropping...but that still would be pretty expensive Jello!

Vaughn