Today was dedicated to exposure. I had previously printed my design using an Epson printer and PosJet film (be sure to print on the "tacky" side.) I applied a drop of mineral spirits to the top of the plate and also to the emulsion side of my film. I was pleased with how well the film laid flat on the plate. However it will slide around very easily when tilting plate for exposure so I made a little shelf out of tape to keep this from happening. I exposed each plate: 1 for 8 seconds, 1 for 12 seconds and 1 for 16 seconds. All had a noticeable purple darkening on the exposed areas and the unexposed areas were noticeably light. I did not use the Stouffer Guide.

 

I prepared the development solution. I didn't have a scale so I used an internet site that gives estimates. 2 teaspoons of sodium carbonate approximates the 10mg per liter recipe. I easily removed the outside film on the plates after degreasing with a piece of tape. The layer removed easily and readily. I developed the plates with some agitation and "scrubbing" (small soft paint brush) for about 1 minute. The 8 second plate lost some photo polymer. The 16 second plate was over exposed as all of the negative area could not be removed. The 12 second was perfect. The emulsion washed out cleanly and the remainder of the emulsion was impervious to removal even with aggressive scrubbing. Exposure time is critical but manageable with a timer. I'll use that Stouffer Scale next time!

 

I washed the developed plates in cold tap water and hardened by exposing to more sunlight. The final plates were fairly dark.

 

I went ahead and decided to etch my good plates. I found that 1 cup of copper sulphate crystals per liter of water was correct for creating a saturated solution. I didn't think that all of the crystals would go into solution but it finally did. I first thought that I had put way too much crystals for the amount of water.

 

I used a 1.5 liter vertical tupperware container to hold my solution. I used some copper ground wire and pounded the bottom 2 inches flat. I bent the wire to fit over the edge of my container. I attached my wire using heavy duty clear package tape. I used enough to also cover the back of piece I was etching. I suspended the plates in my solution and they were about 5 inches apart. I attached the positive wire to my piece to be etched(anode) and the negative wire to the other piece (cathode)

 

I wasn't really sure what to expect. I tuned on the power and could get no reading on the current meter. I fiddled around with the settings and checked the connections but it just seemed that I had an open circuit. I actually touched the alligator clips to each other and got no readings. I discovered that I was using the "case ground" lead and not the true negative lead. I thought that it would make no difference but I switched to the other ground (negative) lead and got current flowing. I used info from some of the tables on the Green Art site. I new to keep voltage low so I selected 5 volts. I got .6 amps of current at 5 volts. The tables seemed to "tell me" that I needed to be up around 2 amps but I could not obtain 2 amps unless I went to 25 volts. So I just ran at 5 volts and .6 amps for 15 minutes. This piece was poorly etched. The etching depth was very minimal and spotty. I realize that the etching process should take much longer but I wanted to do something to get that amperage up so I aborted experiment #1.

 

I mounted a new piece and setup the process at 7 volts and .96 amps. I ran the experiment for 21 minutes and then inspected. I could tell that I was etching away nicely. The etched area looked "crisp", uniform and "deep." I ran for another 24 minutes (total of 45 minutes) I also raised the voltage to 10.5 volts to get around 1.2 amps. (Yes, I realize that I no longer had a controlled experiment) Anyway the inspection at 45 minutes was disturbing. I could see "wrinkles" or irregularities in the emulsion around the lines. I stopped the experiment and placed the plate in the stripper (1 cup of calcium carbonate in the 1 liter of water.) By the way, the purple emulsion stripped away nicely in about 1 minute.

 

The design was etched to a depth of about .3 mm. I would have been delighted with the result but I had these disturbing "burrs" or tracks or irregularities around some of the lines instead of real sharp edges. I don't know if the reason is my "greed" of raising that voltage to 10v or was their something wrong with the resist emulsion.

 

I will run the experiment again but run longer and just keep that voltage at 5v and .6 amps and inspect often to check on the progress. I would love to hear from someone who might be able to diagnose my "rough edges. I have attached pictures of these plates including an enlargement of the eroded areas.

 

My piece is good enough for me to carry it forward for a patina step.

 

My next report will be on optimizing the etching process before I start down the road of Champlevé.