[pure-silver] Re: You're making your own emulsion!
- From: "Gene Johnson" <genej2@xxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 31 Dec 2004 13:52:30 -0800
Interesting story. Testimony to intelligence and hard work. Can't imagine
how much insight into the workings of our medium you've gained in this
project and it's good to know that such a key technology is in such good
hands. This stuff needs protecting. I've been looking for info on edwardian
era portrait studio processes and have actually found very little. I'm
starting to understand that much knowledge simply gets lost in time. If all
else fails, you can now ensure that future generations have something to
print on! Do you have any thoughts about producing your paper in any
quantity ever?
----- Original Message -----
From: "Ryuji Suzuki" <rs@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, December 31, 2004 12:51 PM
Subject: [pure-silver] Re: You're making your own emulsion!
> From: "Gene Johnson" <genej2@xxxxxxx>
> Subject: [pure-silver] You're making your own emulsion!
> Date: Fri, 31 Dec 2004 08:12:50 -0800
>
> > I know your emulsion has been mentioned before, but I just thought
> > I'd take a moment to say bravo! That's pretty darned
> > impressive. I'd love to see a scan or two.
>
> Thanks - I should have some surviving test strips that I can scan.
> I don't know how much a scan can convey, though.
>
> My homemade papers are hand coated on watercolor or printmaking paper
> of 300 g/m^2 weight, and they make a perfect holiday's greeting
> card. So most of good ones were disposed of that way :-)
>
> I started vaguely playing with the idea of making my own emulsion at
> the beginning of 2003. I needed to rent a dedicated darkroom to
> realize this project (I'm a renter, and I had a darkroom at the corner
> of my residence, where I could print only during night). I found a
> space and about to sign the lease but the guy was a total asshole and
> refused to do the plumbing work at the last minute, even after I put a
> lot of building out work. So I had to find another place, which took
> many months. I moved in to my current place August 2003. Finding the
> right space was more than half of the problem. If you already have a
> light tight garage with running water, it is possible to make emulsion
> in house.
>
> In chlorobromide emulsion, it took me some work to make emulsion fast,
> high contrast and absence of fog. Chlorobromide emulsion is very
> sensitive to impurities from anything, and also react with many
> things. It's a great trouble because paper sizing has to provide very
> good chemical barrier to prevent emulsion form touching the
> paper. Otherwise, the print will be pure black, Dmax everywhere. But
> it is worth the trouble because the tonality is different from bromide
> papers. The emulsion contrast also responds well to different
> development techniques in tray, unlike many modern commercial materials.
>
> In bromide emulsion, it is absolutely essential to remove reaction
> byproducts in the middle of emulsion making process. This process is
> called desalting or washing. Without this process, chemical
> sensitization process to boost the speed and contrast will be greatly
> impaired. Traditionally, this was done by gelling the emulsion to
> stiff jelly, cut it into noodles, and soak it in cold water for
> several hours with many changes of water. This is exactly the same
> idea as soaking salted codfish (a Portuguese favorite, but possibly also
> Scandinavia as well.) in water for two days with several changes of
> water before cooking. I had to improve the efficiency of this step in
> order to make "production" quality plate emulsion without hiring a
> technician, which is not an option for me. I read great many times
> this old Kodak patent (expired), which chemically modified gelatin so
> that it can be made insoluble as desired, and can be solubilized
> again. The method worked in principle, but when I tried, it worked
> very poorly. I think the patent was hiding one important step that
> must be used in order for that method to work well. Well, knowing that
> the method should work in principle but doesn't work in practice, I
> started varying parameters that are not described in the patent, and I
> finally found what was missing in the patent. After that,
> experimenting plate emulsions became a lot easier.
>
> Bromide emulsions require this troublesome desalting step, but the
> emulsion is generally more robust and easy to handle than chloride
> emulsion. With the idea of making prints with my existing negatives, I
> started this venture with chlorobromide emulsion without knowing the
> difficulty. If anyone is interested in starting the emulsion venture,
> I recommend to start with a bromide printing emulsion. If you screw
> up, the most likely error is too low a contrast as a printing
> emulsion. That way you can use it as a very slow plate emulsion!
>
> After figuring all these, I read the history of Fuji Photo Film. The
> company had bromide paper when the business started in 1934 (it was a
> spinout of a celluloid company, to which a dry plate company
> merged). But commercial chlorobromide paper had to wait for many
> years. It seems that it was not just me who had extra trouble by
> trying to chase this difficult animal. AGFA had a decent chloride
> paper by WWII. The formulae for AGFA Lupex printed in post-war
> intelligence report have traces of how they managed the problems.
>
> By the way, another pure-silver participant Terry Holsinger also made
> his plate emulsions.
>
> --
> Ryuji Suzuki
> "Keep a good head and always carry a light camera."
>
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