Sodium Alginate Acrylic Hard Ground: Experiment 3

Experiment 3: Sodium Alginate and Zea Mays Stop Out Hard Ground
Researchers: Zoe Dong and Megan Ogden
Date: 9/20/2018
Temp: 73 degrees
Humidity: sunny, mild humidity

Using our observations from Experiment #2, we decided to start with a 1:24 ratio of sodium alginate to Future floor polish because this ratio produced a solution with the right combination of fluidity and thickness for a ground.

To begin the experiment we mixed ½ tbs of Sodium alginate and ¾ cup of Zea Mays Stop out to achieve a 1:24 ratio.

This mixture was not fluid like we expected. It immediately started clumping up and became thicker than we anticipated. We hypothesized the different results were due to addition of Gac 100, which is part of the stop out mixture. The Gac 100 was not included in our first test with a 1:24 ratio. In the first test, just future floor polish was mixed with sodium alginate. We let the sodium alginate and stop out mixture sit for three hours to see if over time the clumps would dissolve. 

After three hours of sitting with periodic stirring, the mixture was still very lumpy and thick. This ratio,1 part sodium alginate to 24 parts stop out, is too thick to be a pour on or paint on ground. Because of these results we modified our test to include ratios with a greater amount of stop out to sodium alginate. The table below illustrates our tests: 

Cup Number Ratio Amount of Sodium Alginate to Zea Mays Stop Out Observations Observations after 2 hours of sitting  
1 1:48 ⅛ tsp to 2 tbl When mixed; clumpy at first, but dissolved out. Fluid, but not thin.   Thicker than the original stop out, pours slowly when cup is tipped. some clumps remaining.  
2 1:36 ⅛ tsp to 4.5 tsp When mixed; clumpy at first, but dissolved out. Fluid, but thickened to a point where is slowly poured when cup was tilted. Thickened to become too stiff to pour.
3 1:96 ⅛ tsp to 4 tbl When mixed; almost looked like the stop put was unchanged (still very thin) Thickened a little, still runny and pours quickly when cup is tipped. Some clumps remaining.

We let all mixtures sit for 2 hours, mixing periodically to break up clumps.

The 1:48 mixture, clumpy at first

After reviewing our observations we decided to remove the 1:36 ratio from our testing because it was too thick to be either an effective pour on ground or paint on ground. We prepared four copper plates by beveling all edges, buffing the surfaces using first a scouring pad followed by steel wool, then we degreased using Bon Ami and soy sauce. After our plates were buffed and degreased, we applied the 1:48 and 1:96 sodium alginate and stop out solutions to the plates as follows:

Plate Number/ Sodium Alginate to Stop Out Ratio Application Method/Drying Method Observations during application Observations after application
#1/1:48 Paint on using a foam brush/Air Dry Very streaky. Painted one thin layer, let dry for 5 mins, then painted on a second thin layer in the same direction as the first. Second layer covered most of the copper, but a few streaks of copper showing remained.

Close up of brushing on 1:48 mixture.

Began to dry within 5 mins
#2/1:96 Paint on using a foam brush/Air Dry Somewhat streaky, but good full coverage because of self leveling. Able to keep the layer thin.

Close up of brushing on 1:96 mixture.

Began to dry within 5 mins


Pour on/Air Dy


Covered fully, slightly thicker than the brushed on ground. Clumps poured on and stuck to the plate.

A thick pour

Began to dry on edges after 5 mins. Inner plate began to dry after 15 mins due to its thickness.


#4/1:96 Paint on using a foam brush /Convection oven at 275 degrees F for 8 mins Somewhat streaky, but good full coverage because of self leveling. Able to keep the layer thin.

The 1:96 after heat setting

Dried with a mat finish. Looks like good coverage, no copper shining through.


Comparison between 1:96 brush on, on left, and 1:48 brush on, on right.


We let the four plates sit for one week.
Experiment 3, Continued
Date: 9/27/2018
Temp: 73 degrees
Humidity: sunny, mild humidity

From left to right: 1:48 brush on; 1:96 pour on; 1:96 brush on and heat set; 1:96 brush on and air dry

Plate #1, 1:48 painted on air dried, and Plate #3, 1:96 poured on air dried; were both observed to be too thick to draw into. We took an etching needle and drew through the plates and noticed the needle catching and tearing the surface, rather than easily drawing through it. Therefore, we removed Plate #1 and #3 from our research.

We continued to test Plate #2, 1:96 painted on air dried, and Plate #4, 1:96 painted on heat dried. To test these plates we drew on them with etching needles. It was clear that the heat set plate (Plate #4) was harder to draw through compared to the air dry plate (Plate #2). The etching needle would have resistance and skip as it was drawn into the Plate #4, but it would more fluidly draw through plate #2.


Un-etched 1:96 plates

Both plates were step etched in time segments of 5, 15, 45, and 60 mins in a Ferric chloride bath with a baume of 38.

After 5 minute etch

After 15 minute etch


After 45 minute etch

Once etched the plates were stripped in sodium Carbonate. Plate #4 took twice as long, roughly 30 mins total, to strip.


Differences in stripping

Once stripped we inked and printed:
Paper: Hahnemuhle Copperplate
Ink: Graphic Chemical INK CO Bone Black #514C oil based etching ink
Modifier: Linseed oil
Wiping: Tarlatan and newsprint

We modified the ink very slightly and carded the ink onto the plate with matte board and then wiped both plates using tarlatan followed by newsprint to remove any residual plate tone. We soaked the paper Hahnemuhle copperplate for 15 mins then blotted it dry between two towels before printing.

The results of the prints showed the difference between the two grounds well. The skipping and difficulty of drawing through the heat set ground is evident in the thickness and inconsistent printed marks. The lines printed from plate #2 are sharper, thinner and more consistent. From this test we concluded that air drying the sodium alginate acrylic hard ground creates a better drawing surface.


Top image is the heat set plate. Bottom image is the air dry plate.


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