anachronism said:Buy Ferrous Sulphate and save yourself the work.
Yes I made my own just to see how easy it was and yes it's easy but see how cheap the pure product is, and it's not worth the hassle.
I live in a very rural area that even the couriers will not deliver and the nearest agent is forty five minutes away, the thing with ferrous sulfate it will oxidize when exposed to air.
The one time I was in Winnipeg bought a large sack of it and it was already brown. 3.5 hours to the peg to return a $20.00 bag rotten ferrous sulfate not going to happen.
I did manage to clean some up a bit with dilute hcl which cost me $15.00 for each 4 liter jug, my sulfuric acid cost me nothing as the farm has a large stock pile of old battery's.
The impurity's are easily filtered out using the right cloth, I have a fire retardant cloth used in curtains which is made from fiber glass which is impervious to sulfuric acid.
I tried using some SMB that I had but found out this afternoon that five years in storage rendered it useless, thus the call for making my own copperas.