AlternativePhotography.com

Historical photographic methods in use today – the art, processes and techniques of alternative photography

Hi all,

I've been working in Gum Bichromate for a year or so now. I've got a glass coating rod which works great for prints up to 11" wide, but my quandary of late has been how to get a good coating on big paper.

I recently made a series of 5 prints for my College capstone course using gum bichromate measuring in at 30x44 inches. I used a water mister to spray the emulsion on. And it worked fairly well actually, but I'd like to get the process a little more refined, and get a smoother, move even coating. So I was wondering if anybody had some suggestions.

I've been considering an airbrush set, but I'm not sure how well that would work out - and if the emulsion will spray out well. It's also a bit pricey as I don't own a compressor. I'm willing to spend a hundred or so bucks on this if it's a good solution.

Thanks in Advance,

Matttail

I've used a small car tyre pump (12v) attached to a car inner tube to power an airbrush. Never used it in Alt process work though. You could do this for less than $100 off e-bay

I'd be careful about spraying solutions containing Potassium Dichromate about unless you have a good face mask.

Phill

I use a 2 inch water color brush. First I wet the brush with water and wait a few minutes for the bristles to plump up. Then I dip the tip of the brush back into clear water and blot off the excess on newsprint until it is just damp.not drippy wet.

then I dip the brush about 3/4 inch into the emulsion solution and start applying to the paper from one corner using short strokes. I replenish the brush frequently with fresh emulsion and when the brush starts to drag I take an eyedropper of water and add more moisture to the upper parts of the bristles just enough to make the emulsion glide onto the paper.


The key to even coating is to have plenty of emulsion mixed and to work quickly and precisely. I routinely coat 32" x 40" paper this way. it takes about 5 minutes to cover evenly.

it works very best if the air is humid. here in the SW USA sometimes the humidity is under 20% and then I just tear my hair out...well now I dont even try to coat big papers in that dry of conditions.

Thanks for the tips. I'm going to put out and buy a good quality brush and try that. Seems like the best way to go. I guess my nature is to be impatient and not want to work with a brush for a pieces of paper that big - but 5 min really isn't that bad.

I live in Chicago area now, so lack of humidity shouldn't be a problem - though a humidifier might not be a bad idea for the winter months.

Thanks for the tips!