Art Articles & Reviews

} Recycling Aluminium Plates Printmaking Series - Part 20 of 21 By Nik Semenoff For most art lithographic printers, the use of a plate was a one-shot deal. Regraining the surface for traditional lithography so it would hold a film of water was not practical for them. The cost of plates became a major factor in the price of an edition. For students it was a budget breaking experience when plates broke down from faulty processing. As an instructor I saw students become frustrated with printmaking when they lost their expensive plates and could not afford more. I started research into a number of avenues that looked promising. In the end I came upon a solution that is extremely simple and first overlooked. Unlike traditional plates that require a texture, waterless plates work best if they are fairly smooth. The backs of the traditional plates is usually dirty with ink and oxides that aluminium quickly accumulates. After using the front of the plate for projects on traditional lithography, the plate is kept for recycling and waterless printing. One can use the grained side for waterless as well if that is the only process being practiced in the studio. The first step is to remove all the dried ink on the back - this has to be done unfortunately with hydrocarbons. There are some commercial cleaners containing citrus d' limonene in an miscible solution, which are safer and should remove the dirt. There will still be a layer of aluminium oxide that is best removed. This is done with a scrub pad made from scrap carpet glued to scrap lumber and a weak solution of sodium metasilicate. This chemical has replaced the environmentally harmful TSP and available in paint stores. Along with a 3M green scrub pad held by the carpet - and the metasilicate, the surface is scrubbed until water flows evenly over the surface. This procedure produces a thin layer of aluminium silicate that servers two purposes. The silicone to be applied to the surface will bond better to this layer and make a better plate. Later, when one recycles the plate again, this layer is attacked by the bifluoride much easier. The drawing and processing of the plate for printing is done as usual. After the edition, the ink should be removed with a strong detergent and put aside for later use. The first move in this step of recycling is to remove the silicone. The only sure way to get if off the surface is to break it down with a weak solution of hydrofluoric acid. This acid is extremely dangerous when used in pure form but is available from glass workers as paste. Under a number of manufacturer labels, sodium bifluoride is mixed with other materials into a paste to spread on glass and produce frosted designs. A very small amount of this is added to water in a plastic container. Some phosphoric acid is added to increase activity. Using rubber gloves and a pad from scrap carpet, the solution is spread over the surface until it attacks the silicone. For those concerned about the amount of HF in the solution, tests to a properly prepared mixture shows it is around .35% HF. Considering that glass workers are using the more potent paste without harm, printers should be able to be as careful. For the final preparation of the surface, use the same 3M pad and sodium metasilicate as before. This will abrade any loose silicone still sticking to the plate and add a new layer of aluminium silicate. The plate can be recycled many times over until bent or damaged in other ways to make printing difficult. This technique allows students to print to their hearts content and improve their skills. Practicing printmakers no longer have to worry about plate costs in making their editions. ________________________________________________ Copyright © 2004 Nik Semenoff Nik Semenoff Artist-in-residence University of Saskatchewan Visit Nik Semenoff's website at duke.usask.ca/~semenoff/ for more information.