a. Always read and follow the instructions carefully. Making a mistake
when mixing can be very costly and time consuming for everyone. If you make
a mistake discard all chemicals and start again with a new set of chemicals.
NOTE: Always add the chemical to the water.
chemical in the mixing container and then add water.
especially important when mixing an acid solution.
b. When mixing more than one chemical, mix them in the order they are
used (developer, stop bath, and fixer).
This procedure will minimize the
possibility of contaminating the chemicals if the mixing container was not
washed thoroughly. The film goes from the developer into the stop bath and
then into the fixer so a little of each chemical is carried over to the next
chemical. There is no harm done when it happens in that order. However, it
doesn't take much fixer added to the stop bath or developer to contaminate
Likewise, a small amount of stop bath in the developer will cause
c. Thoroughly wash all the equipment you use after mixing each chemical
including the thermometer, mixing stick and measuring beaker.
If you are
using an automatic mixer, flush the pumps and hoses with fresh water.
You should now be familiar with the basic types of
photographic chemicals, the types of film that are processed in different
chemicals, and how to prepare these chemicals. If there are any areas you
are not sure of, go over them again.
If you feel competent in your
knowledge, go on to Learning Event 2.