The Pro-Vertical Etching Tank, by Keith Howard

(from "non-toxic intaglio printmaking" , written by Keith Howard)

When I first adopted the idea from industry of using a vertical etching tank for printmakers, I made my own tank from Plexiglas. After a few years of trial and error, I had yet to develop a leak free tank. Invariably, every siliconed or fused joint of these Plexiglas tanks leaked. I tried many types of adhesives, but no avail. Sometimes it would take4 about 2 years before the seams leaked. I invested hundreds of dollars in a cast Plexiglas double-skinned tank and it still leaked. I gave this tank over to a boat-builder who went to the trouble of fibre-glassing the seams and this also eventually leaked. The only answer to a leak free tank was one that did not have any joined seams. I approached a local Canadian manufracturer and worked with their engineer for a year to develop a leak-free vertical etching tank that couls service the etching needs of printmakers for many years. Developing this tank was no simple matter. There were improvements that I wanted to design into this tank that would make the etching process more efficient. These improvements follow:

The Pro-Vertical Etching Tank has a lid that fits snugly around the sturdy top lip of the tank. This top lip is so strong that when the tank is full of etchant there is no distortion, allowing the lid to easily fit. This lip also acts as a drip catcher, and is strong enough to support the loaded weight of the tank for inserting into a counter top, as shown in Illustration 8. To fit this vertical tank into a table top, it is necessary to make the table or counter top in two pieces that lock around the tanks lips. This type of collar lock fits snugly under the top lip of the vertical tank. Once in place, supports are screwed to the underside of this collar to hold the top together. The gap at the top of the counter resulting from this joint can be sealed with silicone. Holes can be drilled into the counter top to accomodate the aerator system. This vertical tank has been designed to be free standing. It can be placed directly on the floor or on a stand to elevate it for ease of use. This tank has the capacity to hold approx. 30 litres of etchant, and is recommended for ferric chloride or the Edinburgh Etch. These tanks can also be used as ImagOn stripping tanks with either a strong soda ash or coaustic soda solution.

The Aerator System. With a vertical etching system the efficiency of the etch is increased by pumping air into the bottom of the tank. This creates a circular turbulence of the etch from one side of the plate to the other, but also increases the speed of the etch. It is also possible to attach an aquarium heater to increase the temperature of the ferric chloride. Warm ferric etches quicker than room temperature ferric. Illustration 10 is looking into the top of the tank and shows the 6mm aerator tube coming from the outside of the tank and going all the way to the bottom. There is a piece of Plexiglas tubing siliconed to the inside end wall of the tank into which the 6mm tubing from the aerator is threaded, see Illustration 11.
	Illustration 12 shows th end view of the Plexiglas plate support with a notch cut out at the end. This notch is lowered over the aerator tube to prevent the tube from crimping. Also shown is an in-line airflow control valve which can be purchased at any aquarium supplier. With this device you can control the aeration rate in the tank. There are some techniques (such as soft-ground) that are etched in a still ferric chloride solution. Most other techniques work best with the aerator engaged.

Illustration 13: shows installation of the airflow control valve. Illustration 14 & 15 positioning the Plexiglas plate hanger. Illustration 16; shows how a clothes-pin (peg) can be used to peg the tape from a plate hanger onto the plexiglas plate support.