tuesday notes in passing.

Emulsion Making

• Laboratory-scale photographic emulsion technique
• Thomas T. Hill. A Tutorial Paper: Photographic Gelatin and Synthetic Colloids for Emulsion Use. Journal of the SMPTE 1968, 77 (11) , 1185-1188. https://doi.org/10.5594/J10922

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DARKROOM safety: If mixed use, meaning, your kitchen, bathroom etc serves as a chemical mixing, storeroom, darkroom — think it is riskier if you share it with others, cats, children… Consider this: powder can collect: cabinets, containers, exhaust ducts, sink drains. Kodak’s dye transfer process relied on Pyro as tanning developer. One lab (MPC in Texas) was referenced by Kodak technicians for years to Portrait / Wedding photographers. The facility was declared hazardous waste site because of the contamination in the pipes and vents.

You aren’t going to be sloppy, but what do you expect to gain by mixing from “skratch” — if you expect that there is a secret to your trial and error chemistry, be prepared to accept more consequence. While it is true that food is a complex of chemicals, which taken in isolation seem dangerous. That is also true of the earth we walk. I am not prepared to call it poisonous, nor hazardous. I am not careful about eating apples, nor am I carefree in mixing raw photochemicals.

I mix chemicals, and have since 1960. In that time, I have increased my skill and cuations considerably. When mixing tanning developers, i use a glove box. My sink has multiple levels of exhaust — for heavier than air, and for lighter, the airborne items. My drains are changed, with the pipes turned in at hazard sites. My exhaust vents are also “smooth” channel with drop caps for cleaning.

Reminder: flakes “flake” into dust; dust into finer powder.

Is there a disadvantage, do you increase risk if you wear PPE? What do you give up, lose, surrender? What are the motives of those on the hobby boards? Is their situation the same as yours? Do you think they would assume your losses if you have an accident?

WHAT DO YOU do for a splash to the eyes? If it is apple juice?

Acute Oral LD50 is the dose of a substance or mixture of substances, in milligrams per kilogram of test animal body weight, which, when administered orally as a single dose, produces death within 14 days in half of a group of 10 or more laboratory white rats.
The oral LD50 of arsenic ranges from 15 to 293 mg/kg in rats, and from 11 to 150 mg/kg in other experimental animals

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TANNING effect — if current products exhibited differential tanning, dye transfer [imbibition printing] wouldn’t require special emulsion making. Using Kodak’s Tanning developer shows no sogn of tanning Tmax, Delta, nor FP4 films. Although silver is developed, and leaves a ‘hole’ in the colloid if it is bleached out, this isn’t tanning — D23 produces the same effect.