e. Sodium hydroxide--A chemical used in many developers for machine processing. It is very
corrosive and may cause burns and dermatitis if it comes into contact with the skin. EVERY
PRECAUTION SHOULD BE TAKEN TO PREVENT CLASS 2 CHEMICALS FROM SPLASHING
INTO THE EYES OR MAKING CONTACT WITH THE SKIN.
Class 3 chemicals are allergy producers--Allergies may develop within a few days after exposure, or they
might not be detected for years. The degree of sensitivity to a chemical varies with individuals.
Phenylenediamine, mono-methylamine phenol, hydro-quinone, sodium bisulfite, sodium borate (borax),
and sodium sulfate are examples of class 3 chemicals.
Class 4, Solvents--All solvents and their vapors should be regarded as poisonous. When working with
any type of solvent, good exhaust venting and forced ventilation are a MUST. Tetrachlorethylene is
considered the safest of all the solvents. Carbon tetrachloride, on the other hand is considered the most
dangerous. Carbon tetrachloride can cause liver and kidney damage, or death as a result of paralysis of
the brain. When heated, carbon tetrachloride gives off phosgene gas. THIS SOLVENT IS SO
DANGEROUS THAT IT HAS BEEN OUTLAWED IN THE ARMY.
Fire/Explosive Hazard chemicals:
Many photographic chemicals are potential fire or explosive hazards and must be handled as such.
Among the most common are:
Sulfuric acid--A strong dehydrating agent that extracts moisture from most materials. Film,
wood, and paper can be ignited by sulfuric acid.
Glacial acetic acid--In strong concentrations is a very dangerous chemical.
FOR DARKROOM USE, ACETIC ACID SHOULD BE DILUTED TO 28%.
Acetic acid is incompatible with chromic acid (tray cleaner), nitric acid, and sodium peroxide. If
combined with strong oxidizing chemicals, acetic acid will explode.
Hydrogen peroxide--In concentrations of 30% to 70% is a fire hazard.