Hardener for a home made emulsion

[aca91]

Hello APUG,

I've been starting to prepare my own emulsion recently, following Kodak's AJ-12 recipe. Although the quality of the results has not been consistent (my first batch came out awesome, although the second one left a lot to be expected), I think that getting more precise tools will help. By the way, I'm using it as a paper emulsion (actually, I'm coating on canvas, but I'm exposing negatives over it), is it recommended? Are there any other recipes at hand? I know about the lightfarm, but many of the ingredients of their kitchen recipe are not available in my country (they should put substitutes to things like Photo Flo 600 easier to find!). The main purpose of this post is to get some help on hardening and emulsion usage. Coating the emulsion on canvas has been easy so far: I use a brush to do that, and the only problem I've experienced so far is some "white bubbles" that appear randomly over the image (any ideas?). If the canvas is not prepared (i.e. precoated with gesso, which is an acrylic base that seals the pores of the cloth) the emulsion adds easily, but it takes more material to coat the surface evenly than a prepared canvas. With the prepared canvas less emulsion is needed, but some times it is very slippery and the emulsion doesn't stick to it easily. Some time ago I read the instructions for Liquid Light, and they suggested to prepare difficult surfaces with wood varnish: will that help in this case too?. I also remember that they suggested to add pure dektol to the emulsion: can I do the same with my AJ-12? Are there any other additives that I can add to my emulsion while it is liquid?

Finally, I want to know about hardener. My goal is to crackle my emulsion, like an old painting. I read about an art forger who, in order to fake the craquelure of some paintings, coated the canvas with a thin layer of bakelite, on which he painted the image. Later, he baked the painting and it cracked. My idea is to make something similar with photography. As formaldehyde is a basic component of bakelite, and also a widely used emulsion hardener, I'm guessing that it can be used for this purpose. Do you have any ideas? Is there any recipe of an emulsion hardener that can help me? Can I "over-harden" my emulsion to help it crack? Do you have any recipes of other emulsions, or anything else that might be useful for this ideas?

Thank you in advance

 

[ruilourosa]

glutaraldehyde!
check for the formula online or darkroom cookbook

 

[aca91]

it does not appear on the darkroom cookbook. could you be more specific? how to add it, where to find it and such?

thank you for your reply.

 

[nicholai]

Any art-store will sell you things to make it crackle.

 

[aca91]

...

 

[nicholai]

Wasn't that what you were looking for? Just trying to be helpful here.

 

[aca91]

thank you for your reply, but I was hoping to get some more information (...) like what kind of product, how it reacts to emulsion etc

 

[nicholai]

Unfortunately i don't have much information about it, but i've seen several different products, whose purpose was to make anything you put on top of it crackle. You can ask them and have a look, perhaps.

 

[dwross]

You're stepping into more or less unknown territory -- always great fun, but it comes with the price that you may have to dig up a lot of your own answers. All most of us can do is shoot you our best-guess suggestions. Here's mine: Try whatever hardener(s) you can get. Cut up a piece of canvas into many small pieces. Number them. Take notes. Starting with just a small amount of hardener, progressively add measured amounts of more hardener to the emulsion, and sequentially coat the pieces of canvas. When the pieces are dry, process and then try wrinkling each piece to see if you get a crackle you like.

An idea for the bubbles: make your emulsion with less water than the recipe calls for. Right before coating, wet the canvas pieces in plain Vodka and then pat dry. (Trial, error, trial, hopefully success required.)

Best of luck and fun.

 

[aca91]

thank you for your replies! dwross, I love your webpage, but, as I stated, it is hard for me to find things like photoflo 600 or everclear... still, do you think that AJ-12 is a good recipe to coat a canvas with? Also, what kind of hardeners would you recommend? Shall I add the hardener while the emulsion is liquid, or shall I coat the canvas after the emulsion layer is completely settled? What effects does heat cause to an emulsion? I'm hoping to make it crack with a hair dryer, or a heat pistol (I don't know if it is the correct term, but basically I mean an industrial hair dryer). I'm willing to do some tests: first, I would like to know more about hardeners and test them in relationship to results that could be useful to a wider community, until I find the result that I'm looking for personally. Also, what about adding dektol to the emulsion as liquid light suggests? are there any other additions that you would recommend, or a substitute for Vodka (I would prefer to drink it!)

 

[dwross]

Thanks! Keeping TLF up-to-date would almost be a fulltime job in itself -- products come and go (mostly go) so fast. The site was originally intended to be a work-in-progress communal effort, but the communal part isn't so much right now. Not really surprising, I suppose. Photography has always had a big component of secret-keeping mentality. Anyway, I'm plugging away at keeping the "old" updated at the same time as generating new research and recipes. I'm aiming at keeping all ingredients compatible with what Photographers' Formulary has in their catalog. Ian Grant is keeping one eye on European local options. Photoflo 200 is a good surfactant to try.

Vodka is essentially half Everclear (i.e. ethanol) and half water. Set aside some to drink (I do!) but keep some for the darkroom. Great stuff, inside and out!

Hardeners are added one or two of two different ways -- in the emulsion right before coating (the term is a "final") and/or during processing -- before the developer, and/or in the stop bath, and/or with the fix. Steve Anchell's "The Darkroom Cookbook" is an invaluable reference.

Extra heat before the emulsion is exposed, processed, and dry is mostly fatal. Don't. And, I don't think heat after processing will crackle things. Note also, that too much hardener in the finals can make the emulsion very resistant to processing chemistry. The classic hardeners are chrome alum and glyoxal.

Any simple emulsion recipe is as good as any other to try first. You're really going to just have to dig in and play.

 

[aca91]

Thank you very much. I have another question. Since the emulsion is not variable contrast, how can I control the contrast? What kind of developer should I use?

 

[dwross]

"The Darkroom Cookbook" is really where you want to start. It's very good at separating categories of developers and explaining fine-tuning characteristics. And/or, you could start a thread here asking something like "How do I Control Contrast with Development?" The old emulsions are beautifully responsive to tweaking.

Taste in developers is very personal and specific. I highly recommend you play with several before you settle in. As you read the Cookbook, you'll notice that most developers have the same set of ingredients in common. It's mostly a matter of proportions. Avoid the recipes with oddball ingredients (at least in the beginning) and you'll be just fine. One of my favorite recipes, D23, has just two cheap chemicals.

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