Two separate solutions of ferric oxalate will be mixed - the one that has chlorate added to it will affect contrast. There are essentially 13 different grades of contrast that can be used. A whiskey shot glass is just the right size for your drops. For reasons of cost and affect, I use three or four palladium for each platinum. While platinum is four times the cost of palladium, platinum gives more contrast than does palladium.
Palladium adds a warm tone and fine grain to the print.
A small quantity of platinum will give a deeper black to your image. If you use 24 drops as in this formula, you will be able to hand coat an image about 5 x 7 inches in size. If you are going to be doing 2 images, cut the formula in half. The Coating Process Prepare your paper to be coated by securing it with a few small pieces of masking tape. Once the chemistry has been measured into the shot glass, swirl it, then spill it quickly onto the paper.