I have looked into ammonium persulphate, but it seems like you need to heat it and agitate it to get etch times that even start to resemble those of ferric chloride. Ferric chloride just seems more attractive due to it having decent etch times at room temperature with minimal agitation. Am I correct in saying this? EDIT: I have read about a hydrogen peroxide + hydrochloric acid solution that is supposed to be a middle ground between ferric chloride and ammonium persulphate in regards to time, and also provides a clear etching solution. Thing is, I haven't been able to find any specifics about mixture ratios and how strong the acid should be... Does anyone know anything about this?