Some newbie questions about DCG

Dichromated Gelatin.
Tony

Some newbie questions about DCG

Post by Tony »

Martin wrote:Yes. I would also have thought there might be other factors than bloom strength that play an important role here. I used to consider bloom strength as something affecting the setting and melting point of a gelatin at a given concentration. By other factors I'm particularly thinking of the chemical composition of a particular gelatin. In one of his latest posts here, Jeff alluded to the importance of the sulfur groups.
Thanks Martin,

I doubt if John remembers this many years ago when I first started. I got a sample container of Great Lakes (250 bloom) gelatin and nothing I did could get it clear. John suggested various hardening methods, light/ fixer etc as well as IPA temperatures, water baths and sacraficing goats and alike with minimal effect. After spinning my wheels for a few months and concidering taking up underwater bocci ball when I bought some knox and pow became the internationally famos DCG holographer you see today.
Johnfp

Some newbie questions about DCG

Post by Johnfp »

Oh, I do remember Tony. I think I had just finished testing Great Lakes

I tried their Type A (acid processed) of a few different blooms
and their Type B (alkaline processed) of a few different blooms.

Of the type B, I heard that the one dirived from Ossein (Bone) has silver salts occuring naturally, so I even tried some of them.

I would have to go back and look at my notes, if I can even find them, but it seemed the 220- 230 bloom in Bovine (calf not Bone) was the best. I tested 190 through 250 blooms I belive.

Seems Knox is Bovine at 235 bloom.

I made a statement a while ago, and that is the reasoning I tested Great Lakes. In my research I found that it is very hard to control the exact nature of the gelatin from one batch (lot) to another. So buying packets of Knox could ultimately change from one batch to the other. If you really wanted to get serious and have consistant result, I suggested getting Great Lakes at the bloom and type you wanted and then get a few pounds of the stuff from the same batch. I tried to contact Knox and could not get a bulk order of a single batch.

So this poses a question, any of you using Knox, do you look at the lot number on the box and see if it acts any different from one lot to another?
Joe Farina
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Joined: Wed Jan 07, 2015 2:10 pm

Some newbie questions about DCG

Post by Joe Farina »

Johnfp wrote:So buying packets of Knox could ultimately change from one batch to the other......So this poses a question, any of you using Knox, do you look at the lot number on the box and see if it acts any different from one lot to another?
I haven't noticed anything appreciable. I have the feeling that a product like Knox is fairly standardized. But there might be a simple solution to the problem, buy a large quantity of Knox packets and thoroughly mix them all together. Then store the gelatin in a vacuum jar. I have one of these vacuum jars, they have a hand-pump on top that creates a vacuum, they are available at reasonable cost from scientific supply companies.
Johnfp

Some newbie questions about DCG

Post by Johnfp »

Thanks Joe, thats' what I was looking for. Any indications of inconsistancies. Good call on the "make your own large lot of DCG" with the vacuum jar. But if other here back up your findings that they do not vary batch to batch, then you may be right and it is made under close tollerances and the jar may not be needed.

Anyone else?
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