I mix 10 grams ferric ammonium citrate in 35ml distilled water, then 4 grams potassium ferricyanide in 35ml distilled water. Store in separate containers and keep the containers in a dark drawer. When you want to make some prints, mix equal amounts of the two solutions together. The chemicals are cheap. 100 grams of ferric ammonium citrate is around $12.00 dollars U.S. A pound of potassium ferricyanide is around $15.00 U.S. That'll make many hundreds of 8x10 inch prints.