I have been thinking about the use of Citric Acid. This treatment might be harmful. IDK, but emulsions for the most part are at a neutral pH, say around 5.5 - 6.5. Citric Acid could begin to degrade the gelatin. Urea might be better for swelling the gelatin, if that is what you want. For an adhesive, Sorbitol, Glycerin, and other similar chemicals would probably be preferred.
Originally Posted by Hologram
The Schlieren observed is not Nebel, but streaks could be caused by fog and thus be stated that way in the original text as a description of fog (Nebel).
Originally Posted by holmburgers
I'It depends on how much wavelength shift you get. I'd start with 5-10% solutions.
I agree that citric acid may attack a not well hardened gelatin layer. But in my experience (limited to holographic/Lippmann emulsions only) urea is far more aggressive than citric acid.
Originally Posted by Photo Engineer
Generally speaking, I guess better than doing post-swelling would be to have a more "conservative" approach:
- pre-harden the layer prior to processing;
- use a well-balanced colloidal developer (excess of thiocyanate results in loss of silver halide, producing a wavelength shift);
- dry the layer in ethanol or isopropanol.
Right. Moreover, again according to Neuhauss, removing all the mercury from the emulsion after exposure seems to have been a messy business.
Originally Posted by Photo Engineer
Man... I look back at my posts from nearly a year ago saying, "I'm gonna do it soon!" HAH! What a schmuck I was...
But such is life.
In this post by Mssr. Shaffer, he used a glyoxal pre-hardener and his results suggest that it was necessary.
I've got chrome alum, so I'm thinking to try a 3% solution for 4 min. Then proceed to develop with a 2-part GP-2 developer, followed by a wash. I've also got some sorbitol incase it needs to be post-swelled.
Anyways, first time using a hardener so just want to make sure that sounds like a good % and time.
edit: Oh, and is a wash after the hardener necessary or would it be detrimental?
Use 10% chrome alum for 5 mins with a 5 min wash.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Thanks PE... I was way off.
A possible development in the Lippmann world (and what a vibrant world that is! ). The question is, are they suitably panchromatic?
Available for sale at freestylephoto.biz. Prices are pretty high, but only $4.5 per 2.5"² plates.
Last edited by holmburgers; 06-17-2011 at 12:24 PM. Click to view previous post history.
That link doesn't work for me.
So, over the weekend I finally shot and developed a plate. I've got photos that I will post this evening, and although I haven't been able to successfully view interference colors, the whole thing is nonetheless fascinating and quite unlike any other silver-halide film I've ever dealt with.
It was late last night, so it's possible that diffuse sky-light will aid in seeing the colors.
One thought that helped to reinvigorate my interest in interference "heliochromy" was learning about first (or front) surface mirrors. http://en.wikipedia.org/wiki/First_surface_mirror
You can buy these mirrors for reasonable prices (http://howardglassco.thomasnet.com/v...bc=100|3001011) and you can actually make them yourself quite easily from a cheap mirror.
It seems to me that if you coated these plates with a Lippmann emulsion, all conditions of "optical contact" between mirror & emulsion would be met.
Now, the thing that has me wondering is whether or not you can just leave the emulsion on the mirror during processing & for viewing. There seems to be some disagreement, or at least a lack of clear concensus on this.
J.S. Friedman in the History of Color Photography clearly states that the mirror must be present for viewing, and that this is of course difficult with mercury. However, people here on APUG have seen Lippmanns where their very own eyes, and with no reflector present. Furthermore, an old post on the holo-wiki archive has a discussion wherein FSM's are mentioned, but people seem to be saying that the emulsion needs to be removed from this for viewing.
So who the heck knows?!
Let's try to figure this out... because this seems like a home-run technique for modern day Lippmann photography.