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Feedback Report #1

December 9, 2012

I was very gratified this week by the feedback to the idea of silver gelatin web workshops. I have been especially happy with the responses on APUG (Analog Photography Users Group). I posted an announcement there this week and the comments have been supportive, intelligent, and constructive. Thank you.
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Outside the US, there can be confusion about products with American names. To a certain extent, I expect that folks will use the internet to research products, but I do believe I have a responsibility to be as clear as possible. 'Clarity' is always at war with 'brevity'. There are a lot of words on the internet. I don't want to add my share of unnecessary ones, but. . . starting with "Everclear".

I use Everclear in almost every recipe I make — as did early emulsion makers. In the earliest recipes it was simply called alcohol or spirits. It was assumed that the reader had some knowledge of science and knew that the reference was to pure ethanol.

(Geek Bonus: The ending "ol" indicates that the substance is an alcohol. The syllables in front of "ol" indicate the kind of alcohol. This could be a good place to stop and run your eyes over the Wikipedia article on alcohol. DO NOT memorize it or even expect to read and understand it in the sense you would a newspaper. Just let the words you understand, and the cadence of the rest, flow through you — very much in the way you first began learning your mother tongue. Above all, don't panic! There won't be a test. It's not even remotely required in order to learn emulsion making, but I believe it will enrich your experience. I will be suggesting you do this kind of thing now and again.)

Everclear is a brand name for highly concentrated ethanol. It is almost pure alcohol and is used as a preservative, solvent, and fuel, as well as cheap booze. Because it can be dangerous, and could be used illegally, it isn't for sale in some states in the US. In others, it may go under a different brand name. In my state of Oregon, it is sold as Clear Spring, and it's kept under the counter at the liquor store. I go in and ask for a half gallon of Everclear and they reach under the counter and pull out a bottle of Clear Spring. In Minnesota, the brand Everclear is open on the shelves at any liquor store. Each state is different. It is also available online. In Europe, it is referred to as 95% alcohol.

The term "proof", as used in the US, can be confusing. It means twice the percentage of alcohol, i.e. 100 proof booze is actually only 50% ethanol.

Ethanol is available most places that sell lab supplies and is easy enough to order online. Perhaps the easiest thing to do if you can't buy Everclear is to use plain vodka. 80 proof (40%) vodka is close enough to half ethanol and half water for our purposes. If a recipe calls for 100 ml water and 10 ml Everclear, reduce the water by 10 ml to 90 ml and use 20 ml vodka.

Also, there is confusion about what I meant by a "scale reliable to 0.01". Scale specs are noted as "capacity" x "resolution", for example, "100 grams x 0.01 grams". Capacity is how big a load a scale can handle. Resolution is how small an increment of weight a particular scale is capable of measuring (as shown on its display). Does the scale say 5.1 or 5.14? It is generally agreed you need a scale that resolves one more decimal point than you want to weigh. If you really want 5.1 grams of something, it's good to know that you have 5.10 grams on the scale and not 5.14. For our purposes, things are very rarely that fussy, but silver nitrate is expensive and my time even more so. A good scale is good economics.

The rub comes with the trade-off between high capacity and high resolution. Affordable scales come one way or the other. It is cheaper to have two scales — one that is high capacity and one high resolution — than a scale that is both. My 0.01 scale only weighs to 250 grams. That's not enough to weigh a big glass beaker plus the water and chemistry at one time. Fortunately, it is no effort at all to weigh things separately and add them together.

"Accuracy" is just what it sounds like. If you want 5.10 grams, how confident are you that you really have 5.10 grams? Almost all new digital scales are capable of high accuracy. The trick is "calibration" — the last term to learn. Since calibration can get screwed up during shipping, reputable manufacturers recommend the 'end user' preform a calibration. They often supply a calibration weight. If not, a weight — or better yet, a set of weights — is very inexpensive. The instructions will be included with your model. You set a calibration weight on the scale, and basically tell your scale what that weight weighs. You are educating your scale to weigh everything else against a known standard. It is suggested you calibrate frequently.

A question came up about contact printing frames. Is it necessary to have one? No, they are a convenience and a way to assure a good quality print. The idea is to press the emulsions of a piece of film and a piece of paper really tightly together during exposure. A contact printing frame does that quickly and reliably. You can accomplish the same thing by making an "exposure sandwich" with a thickish sheet of glass, a piece of black felt a little bit bigger than your paper, the paper (emulsion-side up, the negative (emulsion-side down), topped by another thickish sheet of glass and weighted down at the corners or clamped together. When we start learning about coating, I'm going to suggest that you get 5 or 10 sheets of 13" x 20" x ¼" glass. I have ten sheets that I couldn't do without. Two of them would be perfect for a contact printing sandwich. Also, I woke up with an alternate idea that I'll test just as soon as the paper that's drying in my darkroom is ready to print. More on that in a day or so.

One last thing: It was suggested that Chemsavers be added as a good source for chemicals. http://www.chemsavers.com/servlet/StoreFront.



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