Etching Aluminum for Artistic Purposes

A. 50 or 60 years ago this would have been accomplished by coating the aluminum with an acid resist such as asphaltum. Then you would remove the asphaltum from the areas that you wish to have etched. You would then submerge the aluminum into ferric chloride until the desired degree of etch had been reached. Just keep in mind that the reverse side would have to also be coated with the acid resist or it will be etched as well. I would imagine that the only difference today would have to do with EPA regulations governing the availability of the chemicals. As with any chemical use, you should use proper caution.

Q. In answering your question, it brings me to my question. Where do you purchase the asphaltum and the ferric chloride ⇦ this on eBay or Amazon [affil links] in a concentration comparable to that which was used 50 years ago?

A. Acid etching with ferric chloride works great on aluminum, brass and copper. Your choice of resist, however, is great today as compared with long ago. In Celtic times it would have been pitch as a resist and nettle juice as acid, most probably :-)

I have done extensive experiments on metals for jewelry using ferric chloride of the type used for circuit board etching ⇦ this on eBay or Amazon [affil links] , and I've used resists such as grease pencil (like for printmaking). Also used nail polish, asphaltum, contact paper, spray paint, and pnp blue (proprietary melt on transfers). The trick seems to be how each holds up in the acid bath... the wimpier ones undercut too fast, and you must adjust the strength of acid.

Make sure you know how you will remove the resist when the etch is complete. Also be mindful of the environment when you dispose of the spent etchant/acid!

A. I have used the same strength on aluminum as for the other metals; however, I always experiment, and test, as it is only exact when under highly controlled parameters.

Q. Since then, I understand there is a way to do the same without icky chemicals, using a reverse plating setup with a solution of common salts. Not sure how, but I have heard of it. Please post if you know of this. Thanks.

A. For basic salt etching of metal you might start with
www.greenart.info/galvetch/beginner.htm#3

A. Try using this method: copper sulphate ⇦ this on eBay or Amazon [affil links] with a mixture of table salt to etch zinc and aluminum plates; this is a great method and much safer.
The materials are very inexpensive and easy to come by.
For the advancement of the Fine Arts. Carry on...

A. A local, and cheap, source of copper sulphate would be your hardware store, plumbing section. A product called Root Kill ⇦ this on eBay or Amazon [affil links] is almost pure copper sulphate crystals. A 2 pound container of it was just $10.

A. Regarding where to obtain Copper Sulphate:

In New Zealand I find that most Garden Centers stock the crystals in 750 gm to 1 Kg packets. Approximately $NZ 10.00 to NZ$19.00. Should be 2/3 that in $US.

A. Hey all, chiming in on this copper sulphate thing.

The "copper sulphate/sodium chloride" procedure is a electrolytic etching method, as made well-known to printmakers by Cedric Green and the Galv-etch, "Green Prints" articles. It is clean and easy and cheap, but it requires a power source. You need a DC current with the plate on the positive and a metal grid on the negative of the same metal as the plate to be etched. It takes a little reading, and some practice, but it's a great and easy way to etch without acids.

Unfortunately, to do so without electricity would require ferric chloride, as far as I know.

A. Ref. the saline etching. The electric power source both speeds up the etch and makes for a crisper/sharper etch but is not a necessity. Etching will still happen without the power. Use equal parts copper sulphate and table salt by weight dissolved in hot water.
More info here www.nontoxicprint.com/etchzincsteelaluminum.htm

A. For etching aluminum, I've found that a product called Alumiprep 33 ⇦ this on eBay or Amazon [affil links] works great. It doesn't etch too deep, but it does etch very even (especially dipping). The product is used for etching aircraft grade aluminum for paint prep, and also cleans the aluminum at the same time. What you end up with is a clean surface that is milky white. The main ingredient is phosphoric acid. As for what to use to resist the acid, I am trying to find that out myself. All I've used so far is painters tape, which a little of the acid bleeds underneath. If you find something that works better for creating designs, please let me know.

A. KEITH HOWARD
THE CONTEMPORARY PRINTMAKER: .

ferric chloride ETCH - PRIMARY! CLEAN ALUMINUM SURFACE TO BE ETCHED WITH CIF CLEANING CREAM. Resist recommended - self polishing acrylic floor coatings such as MOP 'N GLOW lightly tinted with a couple drops in 2 oz M 'N G (should just become opaque) apply selectively by brush or over an area of surface with small ⇦ this on eBay or Amazon [affil links] / air brush. When dry work like soft or hard ground asphaltum, for the marks to etch they must go through this barrier/stop-out for the etch to bite (you will see the metal through the removed 'resist'- depth of etch depends on aluminum ally, length of etch time, and strength of solution.
*If plate becomes very hot then use caution but experiment by diluting the etch solution 10%, 20%, 30% ...
* see how this works.
you