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 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!
for a good paper to try, look to some of the papers alt-process printers use. Specifically, try COT 320. Also look at some of the cold-press papers.
Rollei is partially right about absorbent materials and the need for gelatin...for some of them. If you're talking about fabric or something that's similarly porous, then yes, definitely use it. Papers can be another matter, again depending on how porous it is. Obviously with a non-porous paper, more of the liquid emulsion is going to remain on the top, and thus deliver maximum response. Most papers today are non-porous enough that gelatin isn't 100% necessary, as only a small amount of the emulsion will sink into the paper fibers. Fine-art papers can be a different story...there are some of them out there that are so absorbent that they almost act like sponges. You really need to be careful if you're using one of those.
Thanks, I will look into this COT 320 paper on the internet, and see if I can buy it in any webshop.
Originally Posted by TheFlyingCamera
Any more comments by others?
Any smooth, hot press paper with a weight of 100# or higher should work. Wrinkling is a problem as is bulging with all papers and the trick that I have found is to use the paper on a cool surface. Heat accelerates bulging.
The acidic hardener will hurt the developre AFAIK. Kodak would only use it as a separate solution with a wash after the hardener. It can also cause fog in the developer.
Hardening is a crosslinking of the gelatin by aldehyde groups or metals such as chrome alum. You can use 5 ml of chrome alum or glyoxal (either one as a 10% solution in distilled water) in the emulsion BEFORE you coat. This should harden the coating as it dries before the process. At least, that is what I do.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
OK, thanks for the explanation. I will keep a separate batch of developer without hardener for my normal prints.
Originally Posted by Photo Engineer
In terms of drying the paper, I've resorted to my watercolor tape drying method for fiber based prints, for keeping the paper flat. This means I will first soak the paper, than attach it to a glass plate and fasten it with watercolor tape. After drying, the paper can be safely coated without bulging due to the tensioning in the paper.
The Hahnemuehle acrylic paper worked well for printing. I have some first print results ready now and I am very pleased with the overall look of the print and the feel and structure of the paper. Still some minor issues with even coating though, I have some more training to do.
I have coated commercial liquid emulsion onto cheap watercolour paper without too many problems.
You might be interested in this thread
And a couple of examples from my experiments are here (same thread, just a direct link to one of my posts)
They are digital snaps of the coatings, not scans, because they hadn't quite dried, and I didn't want to gunge the scanner up. Yes, they are a bit foggy, because of my no-to-dark darkroom, as explained in the linked thread.
If I can find them, I'll scan them in properly and post them.
They were coated with a blade I built, inspired by PE's design, but made of plastic and with a couple of adjustments to the shape to help increase the stability of the lightweight blade.
Last edited by ben-s; 08-03-2007 at 06:20 AM. Click to view previous post history.
Lens caps and cable releases can become invisible at will. :D
I think you misunderstood about the hardener.
Originally Posted by Marco B
Kodak recommended Pre Harden (glutaraldehyde or formalin), wash, develop, stop, fix with hardener for soft emulsions or high temperature. They do not recommend mixing hardener with developer.
Also, wetting the paper should not be necessary. I do not wet the paper and can coat fine with brush, puddle pusher or blade. I prefer the blade as it causes less distortion, but that is my preference.
If the paper is dry and taped down, the top edge will wrinkle along the tape joint due to expansion, so I use a cold plate and the minimum of tape to reduce buckling. Also, if you fold up the edges you create a buckle strain along the fold which causes the paper to wrinkle due to differential expansion.
If you prewet the paper, you can have problems with not coating enough emulsion due to the paper already being saturated with water, so you must exercise care.
One way to coat is to melt the emulsion in a tray and then float the paper face down on the emulsion with corners folded up. Don't wet the back with emulsion.
Then lift the paper by one of the folded corners and drag it gently (face down) over the edge of the tray to scrape off excess emulsion. This wets the paper and removes excess emulsion in one operation. It was a preferred method of coating at one time.
No, I hadn't misunderstood, but thanks for your further explanation anyway.
Originally Posted by Photo Engineer
The hardener, according to Rollei's own instructions, is "supposed" to be added to the developer. But of course, next time I might try the approach you suggest by hardening in a separate bath and washing afterwards BEFORE going to the developer. Probably the reason Rollei doesn't recommend it is simply convenience, since adding to the developer removes the extra steps...
I coat only after the paper has dried, so that shouldn't be an issue...
Last edited by Marco B; 08-03-2007 at 04:19 PM. Click to view previous post history.
Ben: I'm working with a brush because I love the effect of that. Thanks anyway for your response.
Originally Posted by ben-s
By the way, I noticed you wrote in one of these other threads:
"2: I need a better drying system. IE. One that is lightproof. I need to be able to leave the darkroom before the coatings are dry."
I realized this same issue... Hence, last week, I spend the better part of three days creating a "home-grown" drying system. It's based on a black developer tray of 50*60cm, which I gave a light-tight hood, and an active - light-tight - ventilation system based on three computer ventilators and a bunch of black matting carton. A light tight air inlet covered with vacuum cleaner filter keeps the dust out.
Bison-Kit glue and black tape were my best friends to put it all together. I stack the paper on glass plates separated by interlocking aluminium U beams (about 1.5 cm between each plate).
Works great! A lot of work but also a lot of fun to build
If I have the time, I may put a description with some photo's on my website...