Starting in Emulsion making ...
I've experimented [a little] in the past with coating sensitive silver salts on paper, and worked with friends a little with commercial liquid emulsion, but I'm now planning on actually starting to make emulsions myself.
I don't have much of a budget, so I was thinking of starting out with something slow, simple and fairly likely to work the first time, and then work up to better, faster, more complex things.
I was condidering the simple chloride emulsion given by Bruce Kahn from RIT (it's been posted here a few times in the past). I know that it'll be [very] slow, but it requires little material, and seems simple all around.
Would this be a good start, or do others have a better suggestion?
Bruce's emulsion would be a perfect start.
I would use a minimum of 7% gelatin in it as one change and I would filter it through a good gold coffee filter before use.
When I make it, it takes about a 10" exposure to a 60 watt bulb at about 4 feet and yields a rather high contrast image depending on how well you do with the pptn.
Basically, Bruce's formula is similar to Azo paper in many ways, but Azo has many more additives and is made a bit differently.
You can use bright yellow safelights with it with no harm. It also keeps well in the fridge and after coating. It coats well with a brush or by dipping the paper, face down, in the emulsion.
1.) My mind is lapsing today: when you say "10" ", so you mean 10 min, or 10 sec.?
2.) Should I attempt to wash the emulsion at all?
3.) Is the contrast too high to use in-camera? (I'm thinking that it's on the high side; just want to confirm). Would i be right in assuming that the speed is probably a fraction of an ISO number?
10" is 10 seconds. 10' is ten minutes. To me at least.
And the 7% gelatin is to use 7 grams in the small batch rather than the 5 he uses.
Do not attept to wash it.
The emulsion is UV sensitive and very slow, so use in a camera would be ill advised. The ISO is fractional as you say, but I have done it. The contrast would be high.
If you want a camera emulsion use the Kodak formula posted in a number of places here on the internet. It was in the emulsion formula area of APUG at one time, but has vanished. That has an ISO of about 3 - 12.
Do not try to coat an unwashed emulsion on glass or film support. The excess salts may crystallize and if so, will cause problems.
Thanks, now that I think about it, I realize that it meant 10 seconds. My mind is not yet awake this morning ...
By the Kodak formula, are you referencing the Bromo-iodide emulsion described in the "AJ-12" booklet? If so, I have a copy.
Out of curiosity, why do you say not to wash it?
What was your approximate in-camera exposure?
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I don't have any suggestion for you but just want to wish you good luck.
I'm ordering the chemicals tonight, and I'll probably make up a batch this weekend, so I'll let everyone know how it goes.
Chloride emulsions are subject to fog if you over wash, and are difficult to control during washing for this reason.
Bruce's formula is optimum for an unwashed condition, and should be left as such.
The other emulsion is the AJ-12 emulsion.
BTW, all emulsions at Kodak in research use the originator's initials plus the sequence number, so my first emulsion would be RM-01. That is probably where this designation came from. If it went to film production it would have a K number for "Kind". Paper uses another system entirely.
If you would like to try a washed bromide emulsion with a speed of 3, I can send you instructions I have modified from the unwashed emulsion instr, with added notations. It looks complicated at first glance bit if you have made it before it is'nt that bad.
Kevin, that would be great. Either post here, or PM me with the info.