Day 7, November 5th, Week 15

Aquatint   With Dave Sully.  As the group had requested, we tried out the aquatint process, mostly using the plates etched the previous week.  As with etching aquatint is an intaglio technique.  The process was invented by Jan van de Velde IV  in Amsterdam, approximately 1650.  The aim is to create a tonal effect.

Again as with etching a mordant – acid – must be applied to a metal plate (copper in this case) to etch – eat away the surface. We previously used a needle to draw lines through a hard ground to etch the plate; with the aquatint technique a powered rosin, made from pine sap, is used as the ground with tonal alteration changed by the amount of exposure to the acid. Unlike the etching process we tried previously, the time required for the plate to be in the acid is quite short, as little as 20 seconds and timing is critical.

Aquatint-Nov-15
Copper Plate ready for printing

I decided to make a new plate, partly to re-familiarise myself with the etching process and partly because my first etching did not seem to lend itself to further attempts at tonality.

The technique.

The plate must be degreased using ammonia, this is done at the sink, when the creamy ammonia suspension liquid coats the whole plate then the plate is ready for the next stage.

The plate is placed into the ‘box’, a contraption which dusts the plate with powered pine resin, this takes about 10 minutes.

Aquatint-box-diagram

The aquatint box has powered resin at the bottom and a draw or opening to insert plates. Powder is blown up by a bellows or a crank and settles on the plates. There is a window so that the engraver can see the density of the rosin. Some time should be left to allow the rosin dust to settle.

The plate is now removed and heated, we used a small gas camping stove, plate on a griddle. This melts the resin and should form an even coat.

We now used ‘stop’, essentially anything that will resist the action of the acid but typically a tar (asphaltum) or a varnish. This is painted onto the plate and where there is no ‘stop’ the acid will bite. Different processes and materials may be used at this point, such as the spit bite process or a soap ground. I would expect to try some of these at some point in the future.  To keep areas free of ink so that they are white in the print, they must be completely ‘stopped out’.

I painted out some areas of the plate, allowed it to dry for a few minutes then put the plate into the acid bath for 20 seconds.  Remove from the bath, wash the plate then I repeated painting the stop, in slightly different areas as well as partially over the same areas.  I repeated this three times, carefully examining the plate each time to try and gauge the likely result.  Obviously for a beginner the estimation of the effect is purely guesswork.  The only way to be sure what was happening would be to clean the plate and take a print after each etch.  The plate would then need to be re-powered, re-stopped and re-etched.  The further one goes and the longer the plate spends in the acid, the darker the result will be.  Dave Sully showed us the charts used to estimate the effect of the time a plate spent in the acid.

Satisfied that I was getting some tonal effect I washed off the ground and resin with white spirit and proceeded to the print stage.

This was exactly the same as printing an etching in week 12 so I will not repeat it here.

Awaiting picture and further text

 

 

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