Thread: Unusual materials as related to straight razors

Originally Posted by guitstik

It's just like about the same formulation for making photography paper/glass plates. The bichromate of potash is light sensitive and mixed with the gelatin, usually made from bovine hoof, hardens when exposed to sunlight. I have used that over the years when doing photographic art works. A search of the US patent office web site did nothing but to confuse the heck out of me by making me chase down differing subclasses. I don't know how you do it Neil, you must have the patients of Job.

Ah, I was a collodion wetplate photographer, also dabbled in ambrotypes (same process) silver gelatin, cyanotype and van dyke amongst others. Silver gelatin looks like it has the process, but the gelatin is just the carrier for the light sensitive silver salts. On its own, gelatin is far too slow for in-camera use - the amount of uv light needed to harden it in the presence of pot dichromate is quite considerable - some sunlight prints taken using contact negs and frames take upwards of 30 mins or more - on a sunny day! The only time I used gelatin and pot di (called bichromate rather dichromate in this instance) was for what they call 'gum prints' - you make separation negs for the primaries then use them to block areas of gum and dye smeared paper - the masked bits remain soft and the gum washes away.

It was fascinating - still got a lot of the equipment including late 1800s printing out frames, 10 inch x 8 inch negative wooden field camera complete with focusing hood/cloth. 5 inch x 7 inch Gandolphi field camera, wetplate back adapter, etc. Never made much money at it, but did get some front covers of magazines, including a full page in the Esso calendar - they didn't save me a copy, so I drove for miles to every gas station for miles around and managed to get a couple of calenders - probably cost me more than I was paid!

Regard,
Neil

Neil, I just didn't go into as great a detail as you do, usually I am typing on my phone. It is called by various names but gum bichromate printing is an old practice, I use it when doing pt/pd prints. It's a long tedious.and expensive process but the results are well worth it. The Luminier brothers also used gum bichromate and dyed starches to create the first color prints long before Eastman Kodak. That also creates beautiful prints if you have a chance to try it, if you haven't already.

Originally Posted by guitstik

Neil, I just didn't go into as great a detail as you do, usually I am typing on my phone. It is called by various names but gum bichromate printing is an old practice, I use it when doing pt/pd prints. It's a long tedious.and expensive process but the results are well worth it. The Luminier brothers also used gum bichromate and dyed starches to create the first color prints long before Eastman Kodak. That also creates beautiful prints if you have a chance to try it, if you haven't already.

I have tried it already! I used to subscibe to Judy Siegal's World Journal of Post Factory Photography around 1998 - she was one feisty lady!

I have a particularly attractive gum bichromate pic of my wife I made around this time - she looks timeless, serene, quite angelic. Luckily, with a process like this it is easy to lose some unwanted details - horns, in her case.

Regards,
Neil

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Originally Posted by Neil Miller

I have tried it already! I used to subscibe to Judy Siegal's World Journal of Post Factory Photography around 1998 - she was one feisty lady!

I have a particularly attractive gum bichromate pic of my wife I made around this time - she looks timeless, serene, quite angelic. Luckily, with a process like this it is easy to lose some unwanted details - horns, in her case.

Regards,
Neil

Picture or it didn't happen!!