Mazakova paper (and a question about gelatin)

Dichromated Gelatin.
Joe Farina
Posts: 804
Joined: Wed Jan 07, 2015 2:10 pm

Mazakova paper (and a question about gelatin)

Post by Joe Farina »

The "Gelatin" entry of the polymer encyclopedia (shown in another thread) includes the following comment (p. 454):

"Reactive groups present in gelatin are primarily, hydroxyl, carboxyl, and amino functions. There are present per 100 g of high-quality gelatin approximately 100, 75, and 50 meq of each of these groups, respectively. These amounts of reactive sites do not vary appreciably from one gelatin to another unless major hydrolytic breakdown has occurred."

I've been under the impression that the light/dichromate hardening affects mainly the carboxyl groups. According to some of the literature (such as the attached paper by Mazakova et al.) the amino groups are relatively unaffected by the light/dichromate hardening effect. Little mention, however, seems to be made of the hydroxyl groups, and I was wondering if there is a reason for this. Also, based on the literature, it seems that hardeners in the aldehyde group (formaldehyde, glutaraldehyde) affect the amino groups. Again, the hydroxyl groups seem to be left out of the picture.

Also, I'm under the impression (from memory?) that the hardener Aluminum Sulfate (found in fixer used for DCG processing) works on the carboxyl groups, but I could be completely wrong. Can anyone shed some light on this?

The following paper was published in 1982, and deals with some issues involving gelatin hardening. Although I wouldn't pay too much attention to the claims of large increases in "sensitivity," it does contain some useful data with regards to gelatin hardening, such as the importance of pH when hardening with formaldehyde (Figure 2).
Attachments
img273.jpg
img272.jpg
img271.jpg
img270.jpg
Joe Farina
Posts: 804
Joined: Wed Jan 07, 2015 2:10 pm

Mazakova paper (and a question about gelatin)

Post by Joe Farina »

ok, I found this in a patent:

"On the other hand, aluminum sulfate can react with carboxyl groups, but not amino groups, present on gelatin"
Post Reply