Engraving Magnesium plates

I once managed a photoengraving company and made my own photo-sensitized magnesium plates. I had the advantage of top-notch equipment and well documented processes which would not be available to the average artist in a studio. But I do know that you could get acceptable results with care without the investment in big equipment. You should be comfortable with handling strong acid (Nitric) and the soluble oils that are a part of the powderless etching process.

If you are serious about the process, presensitized magnesium plates are available for Revere div. of Elektron, and are distributed by Anderson Vreeland and others around the US and Europe.

Here is a link to the A-V website and the various materials they sell. I don’t know what minimums they may have, but I’m sure they can give you some more information if you contact them.

see:
http://www.andvre.com/photoengraving.html

J Henry

As a good smaller-lot alternative- You could get some “Puretch”, which is a film that can be bought by the roll, adhered to plates- and then expose through a negative and follow that product’s instructions.
(I think capefearpress.com has that stuff @ 2 square feet for 10.00- it develops with soda ash and is a good product)

Then, if you’re used to handling nitric acid already/have access to a safe place to etch, you could conceivably make your own relief plates this way. You’ll be doing a relatively long etch from my understanding.

Good luck!

Does the orientation of the plate in the acid affect the etching process? I ask because the tank I have access to requires the plate to be vertical in the acid.
Also any ideas on how long the etch will be for suitable printing results?

Vertical etch tanks are used (generally) with ferric.
You’ll do best to etch zinc and mag with a nitric acid bath, in my limited experience with them. I don’t know if this would be advisable in a vertical tank or not, but I do know they’re designed for ferric/copper.

Either type of acid/metal will work with puretch.

In the 70’s, I worked for a large packaging company which had its own engraving plant, including powderless etching of mag plates. What I remember from that experience as well as from printing school, is that the oil in the nitric acid etchant bath is there to create acceptable shoulder angles on the plate, which are the angles of the edges of the images. Without the oil, the etching process would undercut the edges of the images, leaving nothing to support them. The temperature of the etchant bath is critical for the oil in the bath to do its work. The oil will only adhere to the mag and protect the shoulders from being undercut, if the oil is at a certain temperature. The etching process is an exothermic reaction, meaning it generates heat. In the non-image areas, where you want the etching to take place, there is too much heat for the oil to adhere to the mag, so it does not interfere with the etching. In the image areas, there is no etching going on, so those areas are cooler. At the edges of the images, where the shoulders are, the mag is at a middle temperature between the warmer etching areas and the cooler image areas. This is the temperature at which the oil will adhere to the mag, retard etching, and aid the formation of nicely angled shoulders.

The machine which my employer had, held the plate horizontally, and had a series of paddles above the plate, to agitate the etchant bath. The shoulder angles on the plates were controlled by adjusting three variables: etching time, temperature of the bath, and paddle speed. In this way, the shoulders could be adjusted so that they were not too steep, and not too shallow.

During the time the etchant bath was in the machine, it would become more and more filled up with magnesium from the plates which were etched in it. As I remember, this would slow down the etching process, and had to be compensated for when etching a plate.

Also if my memory doesn’t fail me, one big advantage of magnesium etching was that the spent etchant bath (after being neutralized, presumably…..I can’t remember all the details), was basically plant fertilizer and was not a big hassle to get rid of. (However, this was 40 years ago so things may be different now).

Magnesium etching:
http://magnesium-elektron-gap.com/index.php?option=com_content&view=arti...

to Geoffrey and others

magnesium nitrate is certainly a good fertiliser; is litmus paper still available?

Alan.