Before you start
Warning — please note that working with historical processes brings you into contact with chemicals which if not handled properly can be dangerous to your health and those of others.
Some basic precautions
- Ensure that dry chemicals are stored away from food or areas where food is prepared, and ensure they are out of the reach of children or curious adults
- When handling dry chemicals use gloves at all times, use of a mask and eye protection (dichromates can irritate the respiratory system) are also recommended
- Mixed solutions should be stored in containers that are clearly labeled and kept out of the reach of others
- Ensure that work areas where chemicals have been mixed or used are thoroughly washed afterwards.
Preparing the work area
You do not need a fully light tight darkroom to work in gum. Your basic requirements are as follows:
- An area with a worktable to coat papers that is protected from direct sunlight and fluorescent lighting is sufficient. Depending on the light source you choose to use you will need to consider a suitable space for this to be located
- Once papers have been coated they need to be dried in the dark. A dark cupboard shielded from direct light is fine
- You will also need a space to lay out your developing trays of water — using the bath is perfectly adequate.
- Scales to weight chemicals and pigment — an Ohaus style three beam scale or an electronic one that allows you to weight down to 0.1 of a gram is ideal
- A selection of flat wide brushes — often the japanese style hake brushes are suggested, but other artists brushes can also be used. You will need several of different widths, one of about 6 cm wide and one about 15 cm wide. I use several different brushes for each of the main colours I use
- Jars to store the gum/pigment mixture in - plastic or glass pill containers work well
- Bottles to store sensitiser solution - brown glass medical bottles can usually be purchased from your local pharmacy
- Mixing cups for combining pigment/gum and sensitiser — plastic medicine measures are ideal - you want small ones (an 8 X 10 print only needs about 5 ml of the gum/pigment sensitiser combination)
- Glass or plastic stirring rods — I have a whole pack of plastic chopsticks
- bowls for putting the emulsion in
- A Contact printing frame — this can be as simple as two heavy sheets of glass, or as elaborate as a vacuum easel
- Lots of newspaper
- A hair-drier — for surface drying the coating once it has been applied to the paper
- Gloves for handling chemicals — disposable latex gloves are best.
Notes on exposure control
Exposure times will vary depending on your choice of sensitiser, negatives, paper, printing lights and to a certain extend your pigment colour. A useful test to arrive at some base exposures is to use step tablets with each of the pigments you plan to use — you will then need to do further tests with the same pigments and your negatives.
As a guide my printing exposures vary from 6-15 mins under a 400w metal halide light.