Fellow Shadow Watchers,
Just a couple of additional points - and probably
more as I recall them!
As the plate size increases the voltage/current increases also. I always
work by applied voltage and you will find you have to adjust this at the
required level (see my GIF) as the anodic film begins to build although
16v is a good starting point for medium sized items about the size of
your hand. It's not too critical and fair results can be obtained with a
range of voltages but the time will vary. Aluminium is cheap and your
time is free! Experiment!
You can half the current requirement by spraying the unwanted side of a
plate with cellulose/acrylic aerosol car paint before you begin.
Of course the paint has to be removed after multi-colour anodising and it
can be swabbed off with paper kitchen towel moistened with
cellulose/acrylic 'thinner'. If you buy this in small quantities from
craft shops it will cost an arm and a leg but the local supplier to auto
repair shops will sell a cheap grade (often reclaimed) for use in
cleaning spray guns.
In UK it sells in 5 litre/1 gallon cans for a tiny fraction of the price
of craft shop stuff.
Thinner is highly flammable and it is not too kind to skin and eyes so
take commonsense precautions. In particular don't put the thinner-soaked
paper into the bin until all the liquid has evaporated off or you have a
real fire hazard.
I really believe there is a strong 'making sundials' potential in this
thread but to those who are finding it boring/irrelevant my apologies.
Tony Moss
