Carbon gelatin issues

AltGirl · May 28, 2011

I made three lovely batches of carbon gelatin this morning and poured many great tissues. Then this afternoon.... my gelatin did nothing! I mixed 80g of gelatin with 900ml of distilled water and made gelatin then when I started to warm it (in order to mix in the 50g sugar, 15ml ink and 100ml water) the gelatin all settled to the bottom and the water to the top. One thing that I did notice is that the humidity did increase by 10% between the morning and afternoon.
What am I doing wrong!!?? I am following the exact same steps as I did this morning with completely different results. I am flummoxed!
Any tips would be greatly appreciated! Thank you!

Vaughn · May 28, 2011

How long did you wait between adding the gelatin and when you started to warm it up? One should wait about 30 minutes for the gelatin to absorb the water. If you warm it too soon, then I could see where you might get the separation you got...tho I have never not waited the 30 minutes, so am not sure.

Vaughn

AltGirl · May 28, 2011

I kept the gelatin below 40 degree F (as stated in the recipe) and waited approximately one hour. Could this mean that my gelatin is "off"?

Vaughn · May 28, 2011

Interesting -- I have not heard of the below 40F requirement. I usually just use tap water (50 to 70F depending on the time of year). I stir very well while adding the gelatin.

I suppose having it too cold might inhibit the gelatin absorbing the water.

I have never heard of gelatin going "off". If you have any of the same gelatin left, I'd give it another go.

Water at 60F, mix gelatin in well, wait 30 minutes (gelatin should be a solid mass), and put in a water bath under 120F (I usually use 105 to 110F). That is my routine. You could try it with a 1/4 batch just to check out how it melts.

Over on the Carbon forum we joke about the phase of the moon sometimes messing things up...

Vaughn

AltGirl · May 28, 2011

Thanks for these points - I am going to go through the Carbon Forum to see if any thing else helps out.
I might have been over-doing it in the afternoon. I was super excited about the progress that I made in the morning.

Then again.... there is that pesky moon.

I would love to hear about any other ideas that people might have.

gmikol · May 29, 2011

If you added the gelatin all at once (80g is like 11 packets of unflavored gelatin), it could just be that you did not stir well enough. The outer layers could have hydrated, preventing the inner part of the "glob" of gelatin from hydrating.

It's a wild guess, but it's all I've got. I made a small batch yesterday, myself, but I got a little in a hurry, and I can see sag marks on at least one tissue now that they've dried.

Good luck...

--Greg

AltGirl · May 29, 2011

Thanks for this! I will work on my stirring technique.

Andrew O'Neill · May 30, 2011

Which gelatin are you using? When I used Knox gelatin, I had to make sure that I mixed it in thoroughly and let sit for 30 minutes or a bit longer. Mixing thoroughly, and sitting idle... important.

Jim Fitzgerald · May 30, 2011

When I make a batch of glop I use cold distilled water that I keep in the fridge. It must be 45-50 degrees. I make sure to stir as I pour it in and do it quickly. Sounds like PotM. (phases of the moon!)

Curt · May 31, 2011

Jim why 40-50 degrees from the fridge? Is it because the tap water in your area is not cold enough and is not drinkable, in other words, do you use store bought water for cooking, drinking and printmaking?

When I lived in Santa Barbara I bought water from the store in gallon jugs and used it for all my photo needs. I was hauling water about every other day there.

Curt

holmburgers · May 31, 2011

In lieu of starting a new thread, I hope no one minds if I just append my own recent carbon issues to this thread.

For my tissues, I used the emulsion side of some old RC paper (not fixed out, but long since fogged) and sensitized & exposed them within a week. My result; complete insolubility of the gelatin! It wouldn't transfer, and then after I got frustrated it wouldn't even wash off in hot water.

The smoking gun might be that this glop was kind of old (refrigerated) and has probably been heated up and re-refridged 3 times or so. I've heard that you shouldn't reheat glop too much, so could this be the cause?

Another thought was that by coating it on the emulsion side of RC paper, some hardeners inherent in the paper might've migrated to the goo?

Vaughn · May 31, 2011

The hardeners, but perhaps the silver? Does not Carbro printing use the silver of the image to harden the tissue in the presence of the dichromate (instead of UV light)?

How did you store the sensitized tissues for a week? Unless frozen, sensitized tissue will spontaneously harden well within a weeks time.

Vaughn

holmburgers · May 31, 2011

Well, the sensitization happened the day before exposure, and a dye-imbibition matrix sensitized at the same time etched perfectly.

It's interesting what you say about the carbro reaction... that requires a bleach formula, but I suppose there could be something going on with just the dichromate.

Carbon gelatin issues

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