The DARKROOM COOKBOOK, Third Edition

Equipment 17
customary models. It is accurate enough for quantities to 100.0 grams and has a good counterbalance
system.
The next step up in a mechanical balance is the Ohaus Triple Beam Balance. The Ohaus
will weigh up to 610.0 grams in 0.1 gram increments, which is more than enough for a small
darkroom.
An electronic digital scale, such as a digital postal scale that reads in 0.1 increments, takes
up less counter space and is accurate enough for darkroom work. You can even use an electronic
scale made for measuring powder to make bullets.
If you will often be weighing small amounts of chemicals such as Phenidone, you will
need a scale with readability to 0.01 grams. However, going from 0.1 grams to 0.01 grams
readability almost doubles the price of the scale. If you feel you need 0.01 gram readability,
a suitable model is Acculab’s VIC-212 with 210.0 gram capacity.
A standard-issue two pound spring-loaded postage scale found in most stationery stores
is also handy to have. This can be used for quick weighing of large amounts where accuracy
is not critical—for example, weighing one pound of sodium thiosulfate for a standard hypo
bath. I have a two-pound Pelouze postage scale for just this purpose. The best part is you do
not have to worry if the postage rates go up!
TEASPOON MEASUREMENT
Even though a teaspoon conversion table can be found in the Conversion Tables at the end
of the book, a completely accurate conversion of weight to volume is not possible. This is
because as chemicals age they absorb or lose water molecules, which can cause a change in
weight but not volume. As teaspoon measurement deals with volume, not weight, it is arguably
more accurate than weighing. This is because were you to measure a level teaspoon of
fresh sodium carbonate today, and again in a month or two from the same bottle, the second
teaspoonful would weigh more because of water absorption. If you are consistent in your
work habits, teaspoon measurement should prove to be as reliable as using a scale, especially
since the change in weight caused by water absorption (or loss) affects the potency of chemicals
measured by weight, as well.
STORAGE BOTTLES
Maintain a good selection of photo-grade storage bottles. Starting with 250.0 ml, double the
size and have several containers that are 500.0 ml, 1.0 liter, 2.0 liter, and 4.0 liter. Photo storage
bottles can be purchased from many photography stores and any chemical outlet. A list
of chemical outlets is found in Resources.
Developers should be kept in brown amber glass bottles, particularly if stored for more
than a few weeks. This is because developers easily oxidize and lose their potency when
exposed to air and/or light. Plastic bottles breathe and will speed the rate of oxidation. Highdensity
polyethylene storage bottles are suitable for solutions of fi xer, stop bath, bromide, carbonate,
and just about anything except developers.