Liquid emulsion (Black Magic) and coating
Inspired by Emil Schildt’s great photography work, I recently bought some Black Magic VC liquid emulsion (LPE310) to give it a try...
I feel like a medieval alchemist ;) ... , working with all those liquids, mixing, heating in my "castle catacomb" darkroom :D What great fun are the "I am all digital!" people missing...
However, using all this stuff during a first test run has raised a number of questions, that I hope some of you are able to answer:
1) - First of all, the Rollei Black Magic liquid emulsion system comes with a separate "developer hardener", LPE520, containing glutaraldehyd.
This hardener must be added to the developer, instead of hardening fixers, that I've read about. Now I have never used hardeners before for any of my normal fiber based prints (I print mainly on Ilford Warmtone FB), but I understand the possible need for the hardener with this liquid emulsion. However, here's my question: can I safely use the same developer including hardener for all my "normal" prints on Ilford paper? Or may it harm normal paper and is it better to keep a separate batch of developer without hardener for my normal prints?
2) - In chemical terms, what does the hardener actually do? I have a biology background and it slightly reminds me of the hardening of fatty acids, where double C-C bonds are replaced by C-H bonds resulting in saturated fatty acids with a higher "melting" point. Is this what the hardener does? Or is it a kind of polymerization reaction, with direct bonds between molecules in the gelatin, facilitated by the hardener?
3) - I noticed the hardener is actually a strong (pH 3) acid, and must be added in a quite significant amount to the developer. Now the acidity surprised me somewhat, because won't this kill my developer? As I understood it, the "stopping" effect of the stop bath is simply based on it's acid pH, so adding an acid to the developer seems somewhat contradictory... Am I right that it will at least reduce the total capacity of the developer?
4) – Rollei recommends to pre-coat any absorbent materials, like paper, with pure photo gelatin (Black Magic LPE410). However, is there also any sense in giving an already with liquid emulsion coated paper an extra “top-layer” of photo gelatin, maybe for protection of the emulsion layer, or enhancement of gloss?
5) - Paper choice:
* Watercolor paper:
Most descriptions recommend the usage of watercolor paper. However, I noticed a few problems with that: most watercolor papers have a rather distinct "surface structure" that I do not particularly like for a photo and that will make an even coating more difficult.
In addition, when I bought a piece of 100% cotton based watercolor paper, applying the emulsion resulted in serious bulging of the paper.
Well, actually most papers react with bulging if liquid is applied one sided, so I have decided to apply my "fiber based" drying technique with watercolor tape to first attach a wet piece of paper to glass, and than have it dry so it acquires tension and won't bulge as much when applying the emulsion. Seems to work with the second test run I am currently running...
* Copper printing paper:
Emil Schildt actually mentions copper printing paper as a an alternative to watercolor paper because of the fact it's supposed to withstand significant amounts of time in water. However, buying a piece of this stuff, I noticed it reacted very strangely to water. When I threw it in a bucket of water, there was audible "hissing" sound, followed by about 10 seconds of small fountains of air bubbles coming from the paper. It seems this paper is highly porous and absorbing huge amounts of water, forcefully expelling the air... This doesn't seem to me to be a particularly good characteristic of a photographic paper!
Absorbing so much water will also mean lot's of chemicals that possibly won't wash out. And the air being actively expelled doesn't help in a smooth coating session either... :(
I could confirm the washing issue by throwing it in some of my ferry cyanide bleach used for sepia toning, the ferry cyanide was extremely difficult to wash of...
Out copper printing paper as an option!
* Hahnemuehle Photo Rag:
For my few digital ventures, I have a package of Hahnemuehle Photo Rag. This is non-plasticized matte paper with a very nice surface structure. Just for the fun of it, I have attempted coating this with liquid emulsion on the "non-coated" side of the paper (the coated side of this paper is for digital printing). It worked rather well, and resulted in a good pick. However, as with the copper printing paper, there is an issue: the coated side of the Hahnemuehle paper absorbs ferry cyanide bleach, impossible to wash of... Well, I could have expected this, since it's supposed to absorb the digital inks as well! So, although it could be used if you do not tone your prints (although I still have some doubts about what else the coating absorbs...), out Hahnemuehle Photo Rag!
* Acrylic papers:
Talking to the guy of the art shop where I initially bought my watercolor paper, he came up with acrylic paper. Hahnemuehle has one that is almost identical in surface structure to Photo Rag, but doesn't have the annoying coating! These acrylic papers are scooped with chalk, meaning they will absorb less water and withstand it better. Good characteristics for a photopaper to my feeling. It didn't absorb the ferrycyanide either!
I currently run a test with this paper, second coating done but needs drying time before I can start printing...
6) - Does anyone else use acrylic papers, or whatever other paper are you using and why?
A long posting, thanks for any responses!