ammonium vs potassium dichromate for DCG

[rzeheb]

After a brief search on the internet I learned that the solubility of ammonium dichromate (35.6 g/100 mL water at 20 C) is much higher than that of potassium dichromate (12.3 g/100 mL water at 20 C). Presumably this would make AmDiCr superior to KDiCr for the dip-an-shoot method since you would expect that the higher concentration would allow a greater "loading" of the dichromate into the gel and thus an increase in sensitivity? Thoughts? Also, has anyone tried impregnating the gelatin using an alcoholic solution of AmDiCr rather than an aqueous solution since AmDiCr is also soluble in ethanol? Avoiding the water step might be beneficial since development requires the removal of the water??

Dave, would you be willing to do the experiment?

Ron

[holo_cyware]

These are interesting thoughts. Concerning the lower solubility of the potassium salt, it may have an effect but I personally think it's irrelevant, since you can't go past of 3-5 grams/100 ml even with AmDi as it starts to readily crystalize. It would be interesting to know why potassium dichromate gives redder holograms. The thing is, AmDi is certainly preffered over KDi.

As about the alcohol, although it looks like an interesting idea we should not forget that some humidity is necesarry for the sensitivity of the plate. DCG is supposed to be shot in very humid enviroment, and I personally believe that this is probably one of the pesky factors that will render the DCG masters stunned with random results at times. Some time spent in a small room used for shooting may increase the humidity quite a lot.
So I'd see this as a viable method, but I'm afraid that the gelatin may suffer from alcohol. I wouldn't use absolute alcohol, but diluted and I'd gain time for the plate drying. Definately worth a try.

One thing that needs to be (re)tested for sure is the PDC (http://www.organic-chemistry.org/chemic ... e-pdc.shtm): soluble in lots of organic solvents and the most sensitive. Someone did try it but got no hologram (can't remember who). I'd experiment with it, but giving the lousy holograms I'm getting with AmDi, I guess this should wait some time for now

[Joe Farina]

Some time spent in a small room used for shooting may increase the humidity quite a lot.

This is very true, especially if you're working hard. I've seriously considered some type of breathing apparatus, to keep the moist air out of the lab.

[JohnFP]

Actually, I think it is a great idea the more I think about it. Some testing would need to be done with different concentration of alcohol but once the right concentration is found then the amount of water in the hologram could be controlled. Example: a 99% alcohol may not allow enough moistur in the emulsion but a 70% or 40% may be just right. This way you can sensitize and shoot right away without any drying. I would imaging a quick blow off with canned air may do the trick after the plate is taken out of the alcohol/AmDi bath.

[Tom B.]

I had never heard of jello shots before! Looks like high concentrations are possible.

http://www.myscienceproject.org/j-shot.html