View Full Version : Cyanotype gelatin emulsion coating for metal (aluminum)

09-22-2012, 12:14 AM
Greetings! I hope this might be the best place to post this since it's probably more about coating unusual substrates with gelatin-type emulsion, but I am talking cyanotype instead of silver.

Basically I'm taking both an "alternative processes" (which means cyanotype, vandyke, chromo, lith, toning, lo-fi holga stuff) and a welding class. Obviously these two things are begging to be combined so I starting looking into ideas.

After some research, the first thing I want to try is coating metal (abraided finish aluminum) with cyanotype, but obviously that isn't going to work with the standard water soluble solution. I have read that if I get something like "photo grade" gelatin (such as Rollei/AGFA Black Magic Photo Gelatin, or some other 250 bloom gelatin), make a 20% to 80% water solution of that, then mix that solution 50% with 50% of the standard (already diluted and mixed) Ferric Ammonium Citrate and Potassium Ferricyanide solution, I can brush that on non-porous surfaces to make images.

The thing is that I'm a little confused as to the actual properties of how this stuff should work. Do I need some other coating under the gelatin-based coating for it to stick? Will it stick just fine if the metal has an extremely rough abrasive-like surface? Will the blue in the gelatin be opaque (or how opaque will it be?) and can I tone it just like paper prints?

Right now I'm thinking that the substrate will be something like sheets of 1/8" aluminum that have been scratched/scuffed/abraided/finished/etc with a rotary metal brush such that the surface of the aluminum is rough to the touch but still rather bright and metallic in a matte sort of way. This should mean that the base highlight "color" will be something approximating white and will look metalic, but won't directly reflect light like a mirrored surface. I'm already using this sort of substrate for emulsion lift transfers with Fuji FP-100C.

Can anyone give me some advice or point me to more information? Thanks

09-22-2012, 12:17 AM
On a somewhat related note, I'm also wondering if anyone has any advice on other photographic processes that might be interesting to use on aluminum or low-carbon steel such as some sort of etching, etc.

09-22-2012, 05:33 AM
On aluminium, I'd be inclined to use a clear lacquer first, preferably one designed for aluminium rather than a polyurethane. Then apply a subbing coating of plain 10% gelatine with a drop of hardener added. The Black Magic & Liquid Light gelatins are basically the same type of coating used on photographic papers and are intended for printing on to assorted substrates - If you use one of these, you'd need to "fix out" the silver before using it for cyanotypes....
Unless you wanted to do a cyanoptype over a B&W print.

As for alternatives to regular printing, the idea of printing a resist mask on to a sheet of aluminium and then anodising could be <ahem> entertaining with multiple colours.

09-22-2012, 07:15 AM
Cyanotypes at first reminded me of the prussian blue marking liquid I used to use in shop to mark where I'd be cutting steel. It would make scibe marks show up well, and stuck real well to the metal. It's apparently some sort of dye mixed with laquer, and it stuck to steel super well. I haven't tried it with aluminum. I bet cyanotype chemical could be made to work somehow, just prevent the liquid from beading up as it dries.

I like Pauls's resist+anodizing idea! You could do multiple steps like silk screen! I used to use mylar and a laser printer for making resist masks for copper circuit board etching. I ironed it right off the mylar and onto the metal.