Ferric Chloride (1L)
Ferric Chloride is an acid that is commonly used to etch pattern-welded steels (Damascus). It is almost always diluted when used in the Damascus finishing process, as the more its diluted, the gentler and more controllable of an etch it provides. We prefer to dilute it in a 1:4 ratio of ferric to purified water; at this ratio, it gives a deep etch in 20-30 minutes. A 1:6 or 1:10 ratio is also common, as it keeps the nickel steels more unaffected than the more concentrated solutions, which makes them stay brighter with a finer surface finish.
A workpiece will need to have a clean and even surface finish before going into etching, 400 or 600 grit hand-sanded finish is standard. Degreasing the part is also a necessity, using acetone, Windex, or another brand of degreaser. It's also a generally good idea to dip the piece in the diluted ferric chloride solution for a few seconds and remove it to check for oil or grease spots before leaving it for the full etch time, to ensure an evenly etched workpiece.
Make sure to wear gloves and eye protection when using the ferric chloride, as it is not beneficial to your personal organic tissues. Also, be aware to not put hot steel into ferric chloride as it will create toxic fumes.