Acrylic Sodium Alginate Hardground: Experiment 5, 1:152 sodium alginate acrylic ground pour on and etching test
Temp: 72 degrees
Humidity: cloudy day, high humidity
We mixed a new sodium alginate to ZMP stop out ratio that would be even thinner than the 1:96 mixture because in this experiment we wanted to see if we could come up with a hard ground that was pourable. We created a mixture with ⅛ teaspoon sodium alginate and 6-⅓ tablespoons of ZMP stop out. We let the mixture sit for one hour, stirring it frequently. We then prepared two copper plates by bevaling all edges, buffing the surfaces using first a scouring pad followed by steel wool, then degreased them using bon ami and soy sauce.
Once prepared we brushed on the 1:152 using a foam brush. Brushing was an easy process. The mixture was able to be applied in a thin coat and brushing in the same direction repeatedly removed some excess ground and smoothed out brush marks. There were some brush marks remaining.
On the second plate we poured the 1:152 ground. The plate was held at about a 45 degree angle and the ground was poured on slowly. The plate was moved around in different angles to spread the ground around to attempt to cover the whole plate without pouring more ground on than necessary. Tapping the plate lightly helped encourage the ground to flow in certain directions. The mixture was fluid, but thick enough that it moved slower than pour straight stop out on a plate. The plate was then walked out on newsprint to reduce the collection of excess ground on the bottom of the plate. The plate was tapped after it had been sitting to remove some of the excess and this created a cracking effect, which revealed some copper at the bottom of the plate. Therefore, the process of preparing a plate and pouring on the 1:152 ratio was repeated on a second plate, but this time it was not tapped out after it was walked out on newsprint. The second plate had no cracking effects.
All three plates were left to air dry for one week.
Experiment 5, Continued
Temp: 69 degrees
Humidity: cloudy day, mild humidity
Observations of the three plates with 1:152 sodium alginate acrylic hard ground after one week of air drying:
|Pour on #1||The ground dried in a flaky way, there are bits of copper showing through. This is especially prevalent at the bottom of the plate|
|Pour on #2||The ground dried in a flaky way, there are bits of copper showing through. This is especially prevalent at the bottom of the plate. Slightly less cracking compared to the pour on #1.|
|Brush on||Smooth surface, no copper showing through, very little brush texture.|
Observations after one week of drying:
We noticed that on the two pour on plates, there were some places where the copper was showing through, as if in drying the ground had split apart.
This imperfection is even more visible during the step etching process. We made marks into each plate using an etching needle and step etched them in 5, 15, 45 and 60 min increments.
We concluded that the Sodium alginate does not provide consistent results, but that brushing on the 1:152 ration was the best option because the lines remained intact, there was little to no fowl biting, and it help up to step etching, while the pour on plates had lots of fowl biting due to pour coverage of the ground.