Hydrogen Peroxide Oxidizer                                  Return to Recipes:
As mentioned on the "Recipes" page, this oxidizer only works on copper while the oxygen is being released by the ferric chloride catalyst.  The solution can be reactivated by adding a small amount of Hydrogen Peroxide to the spent solution.  Even as little as a tablespoon of fresh hydrogen peroxide added to a gallon of spent solution will reactivate it for an hour or so.  Since you end up with water and ferric chloride why not start out with water and ferric chloride and add a small amount of peroxide to it when you want to use it?  You can, but you get a better looking patina/oxidation if you start out with a quantity of hydrogen peroxide and let it bubble all day and then rejuvenate it for subsequent use by adding small quantities of fresh hydrogen peroxide.  Theoretically, the ferric chloride is only a catalyst so should not need to be replaced, but adding a drop or two to the solution at infrequent intervals will make it more agressive.

Transferring imagery for multiple plates, sometimes referred to as "counter-proofing" is a process of etching imagery on a "key" plate, then printing that on to a piece of paper, then replacing the key plate with a blank second plate, laying the freshly printed image on the second plate and running it back through the press to transfer some of the wet ink from the "proof" on to the blank second plate.  This transferred ink acts as a resist, so when you put the "counterproofed" plate in the oxidizer only the uninked areas are darkened by oxidation and the areas covered by any trace of ink stay shiny, so the imagery shows up clearly.  This oxidation is unaffected by heat, solvents and grounds. When etching on the plate is completed, the oxidation can be easily removed with Brasso.  This imagery is usually clearly visible under aquatints, but sometimes when it is used for step-biting and an area is deeply bitten it can become hard to see, since the discoloration is eaten away under the rosin along with the copper.  Lines transferred by overlays with transfer paper to the topside of the rosin can be used to deal with this.  The best detailed description of this process I've seen is the Stephen McMillan article at
Multiple Plate Aquatint.

It is also very useful as an indicator of where etching will occur, without actually etching the plate.  If you have just cooked a rosin aquatint and want to check it to make sure it will etch freely when placed in the acid you can place a drop of the oxidizer somewhere on the plate, wait 10 to 30 seconds, and rinse it off and dry the plate. If you see a patch where the drop of oxidizer was, it will etch.  If you leave it on for 10 seconds and when you rinse it off (or blot it with a paper towel) you see a strong patch, it will etch freely.  
If you leave it on for 30 seconds and there is a very faint patch, slow etching will happen.  If there is blockage, the oxidizer will rinse off and leave no trace.  Similarly you can do this to see if etching is happening in some questionable area of a plate.  When you etch the plate the oxidation will be removed.