Copper Sulfate – Saline Etch for Aluminum – Test 5: 16-Plate Step Test

Name: Tessa Chambers & Nick Osetek                                  Date: 3/22/2018

Room Temperature: 68*F                   Humidity, etc: Dry

Experiment Goal: To match and compare our tonal range test to Zea Mays’ original copper sulfate 8 plate aquatint test.

Plate Material: Aluminum (5052)

Plate Preparation (surface prep, ground application, image making process, etc): Buffed with fine grit steel wool, degreased with Bon Ami & soy sauce, backed

Evaluation of Plate Preparation: The plates were much easier to degrease after we buffed them with steel wool.

Etching Bath notes: Fifth use of the bath.

Time in Bath: 3 sec, 10 sec, 15, sec, 30 sec, 1 min, 1:30 min, 2 min, 3 min, 4 min, 5 min, 7 min, 8 min, 12 min, 17min

After Bath Evaluation: The bath was much greenier and milkier, due to the copper exuding from the aluminum. At this point we determined the colour of the bath is an important factor in bath strength. Deep clear blue is a strong bath; as the bath is used copper oxide is exuded from the aluminum. As the copper oxide sits in the bath it turns from it’s typical red color to a milky green, which is elemental copper. The milky green colour of the bath means it’s a little weaker than it was when it was clear blue.

Removal of Grounds (chemicals used and evaluation of effectiveness): N/A

Inking Methods:  Bone Black oil based etching ink, 10% 00 Burnt Plate Oil

Paper Type: Hahnemuhle Copperplate

Soaking Time: 1 Hour

Press, blanket set up and pressure: Praga press, 2 blankets, Right setting: 4/9  Left setting:5/9

Conclusion: With the great range of times we used, we got a nice gradient at our first glance. But when we looked closer there were more inconsistencies. For example, our 3-minute plate was darker than our 4-minute plate. Then, our 5-17 minute plates were very black showing barely any difference in tone. We realized that at a certain point the aluminum would etch to black and stay black and wouldn’t get any darker.  We may be reaching maximum blackness at  a shorter time.  We may discover that it is difficult to find a predictable time to reach maximum black due to the ever-changing chemistry and strength of the bath.

16-plate results.

Duplicate 3 and 5 minute plate etchings. Etch & bath strength inconsistent.

Exspunged copper layer floating to the surface of the bath.

Exspunged copper layer carefully removed from bath for documentation.

Exspunged copper layer after oxidation.

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