View Full Version : Ferric chloride etch time and strength

08-06-2003, 02:35 PM
I have been asked to teach an etching class next month. The school uses ferric chloride, an acid I am unfamiliar with. The former instructor told me that a 10 minute etch in nitric acid (zinc plate) would take 4 HOURS in ferric chloride (copper plate)! He doesn't dilute the ferric chloride and he uses vertical tanks.
4 hours seem excessive to me. Any tips for making the wait shorter would be appreciated.

08-06-2003, 06:02 PM
First let me say that I know next to nothing about etching. But looking at your question I get the feeling that the use of ferric cloride is a safety issue. In that case, using a stronger solution that would reduce the time may not be an option. You could concentrate the lesson on the process of getting the plate ready for etching and simply state that using a stonger acid would result in faster times. You don't give the ages of students involved, but depending on that you would want to give a "don't try this at home" disclaimer. It seems to me that if a stronger acid is not an option, it may be more convinient to use a weaker solution so that plates could be left in the solution overnight so no one has to wait around 4 hours to take them out.

08-08-2003, 02:40 PM
How can anyone wait 4 hours??? Yikes! Well, I was going to say that temperature can be a factor, but of course don't want you to blow up the school. ;) If it is a safety issue is there the possibility that you could offer to put the plates in your own acid-bath at home for the students? Not sure if you want to take the time to do that though. (and assuming you have your own set-up at home, too, oops)

A weaker solution sounds like a good option but not something I've ever heard of someone doing. Maybe they could do an etching plate over the course of a week or so, doing an acid etch every night? Then they could also work on something different day to day such as a drypoint plate to learn how to ink up and use the press? Or a collograph?

Just throwing out ideas since you haven't mentioned the ages or the duration of the course.


08-09-2003, 01:09 AM
I do a 50/50 solution with Ferric. That is how I learned and it works well for me. I would not put a zinc plate in ferric. There is something about the zinc and the ferric that does not mix well from what I am to understand. To be honest once I started working on copper I threw the zinc out the window. A lot of printmakers feel the same way, but each to their own. I have know several students that gave up etching after being forced to work in zinc. Maybe have the students work in copper, use a 50/50 solution, and place the verticle acid baths in a tub of hot water. I work with a flat acid bath, and I have found that the addition of the hot water around the container works very well.