Yesterday I went to a masterclass at Hot Bed Press. These are usually held monthly and yesterday’s was about Photo Carborundum. Martin Kochany, who ran the demonstration, is an experimental printer and often mixes different techniques together or finds new ways of applying them.
Carborundum, or magnesium carbonate, used to be used to resurface lithographic stones but nowadays is often used for collagraph printing. The PVA glue is painted onto a base material, often mountboard or Perspex, and the carborundum powder is sprinkled onto the glue. When dry, the plate is inked up and the rough surface holds on to the ink and produces a strong print.
Martin’s variation was to use a photoscreen to apply the ‘glue’ which was Titanium White acrylic paint/ink with standard screen printing medium. He said that printing medium by itself was not robust enough. Different colours had been tried but Titanium White was found to be the best.
Martin printed the white acrylic ink onto an old metal etching plate. He then sprinkled the carborundum powder onto the plate. He said it would have been ready to use in about twenty to thirty minutes. In answer to a question, Martin said that any image which can be used for a ‘normal’ print can be used for a carborundum print.
Once dried, the loose powder is removed with a soft brush. Martin however decided to do a Blue Peter and used a plate he’d prepared earlier. The plate was a ‘failure’ as an etching, as far as Martin was concerned, but was a good basis for further experimentation. He’d photoscreen printed a half tone image of clouds with the white ink onto the top part of the plate and then applied some ink to the bottom with his fingers.
Martin inked up the plate with red at the bottom and blue for the rest. He wiped the plate with scrim and tissue as normal. There was a relief area from the original etching process to which he applied a roll over of black ink.
Martin printed the plate onto damp paper on a standard etching press.
The final print was pleasing (in my opinion – Martin can always find faults with his work!) and I intend looking at the technique. I particularly like the suggestion made at one point to screenprint onto Perspex then adding linework as drypoint.