	Aquatinting: The Effects of Varying Times and Acid Concentrations Laney Shelley
Student Projects, Print Making

Introduction

I first became interested in this project after seeing an aquatint print in class. Because I knew nothing about aquatinting, this project required a bit of research (library and web!) and a lot of experimentation with the technique. The purpose of this project was to learn about aquatinting using the dust bag method, and to figure out the best way to get an even texture and a wide range of tones in under 15 minutes using zinc plates and different concentrations of Nitric Acid (HNO₃).

I hypothesized that the lower concentration of acid at the longer amount of times would be the best way to reach high quality, wide range of tones.

Background

Aquatinting became commonly known in the 18th century.It was made famous by artist such as Francisco de Goya and Thomas Gainsborouh.

"Wooded Landscape with Herdsmen and Cows," Thomas Gainsborough, 18th century, digital Image found at http://www.metmuseum.org/toah/hd_aqtn.htm.

"The Sleep of Reason Produces Monsters," Francisco de Goya, !8th century. Digital Image found at http://www.artlex.com/ArtLex/a/aquatint.html.

Aquatinting is a form of intaglio printing that uses a porous ground to create a range of tones depending on the amount of ground used and the length of time the plate is bitten. For this particular project I used the "rosin dust-bag method," because it was the most accessible within our lab. This method uses a small cloth bag--in this case, a nylon stocking with the finely powdered rosin which was sprinkled over the plate by tapping on the bag (Ross, Romano, Ross, pg. 98). Various tones are reached in this method by controlling the amount of rosin on the plate and by varying the amounts of time the plate is submerged in the acidic solution. After testing these things I decided to vary only the time and acid in my experiment. The amount of rosin was not varied because the amount on the plate was nearly impossible to measure.

Procedure

Materials:

powdered rosin

hot plate

zinc plate

putz pomade

mineral spirits

isopropyl alcohol

nylon stockings

scoop

stop watch

a solid ground

black ink and oil

satin cloth

print press

paper towels

I began this project by experimenting with the aquatinting technique and the amount of rosin I fused to the zinc plate. To do this I began by polishing the zinc plate with the putz pomade that we used in our etching labs. Once the plate was fully polished it was cleaned with isopropyl alcohol. Once dried, I covered all but a third of the plate with a solid ground. After the solid ground dried, I sprinkled a light amount of rosin onto the zinc plate...when I felt the amount of rosin was correct and evenly covered, I immediately put it on a hot plate that was set to approximately 200 degrees fahrenheit. When the rosin began to turn brown I took the plate off--this only took a few second--and began to bite it in a 3M nitric acid for three minutes. When I used a paintbrush to brush away the bubbles ground was being brushed away so I got rid of that step quick!

After biting a relatively small amount of rosin I cleaned the solid ground and rosin off the plate with mineral spirits and isopropyl alcohol. I then reapplied the solid ground so that an alternate third of the plate was showing, where a more moderate amount of rosin was applied. I placed it on the hot plate this time until the rosin had turned a dark brown...this only took a few seconds. This time when biting, the paintbrush was not used; this method proved to be the best for aquatinting.

The plate was cleaned again and the solid ground was applied to the plate exposing the last third of the plate on which a heavy amount of rosin was applied and fused and the plate was bitten for three minutes.

These same steps were repeated with the 1.5M nitric acid.

For the rest of my project I experimented with the amount of time the plates were etched in 3M and 1.5M nitric acid. Just like above I began by polishing and cleaning the zinc plate. However, this time I would only use the solid ground to cover the sides and edges of the zinc plate. I would then put a moderate amount of rosin on the zinc plate and fuse it with the hot plate. I would then bite the plate in the acid for smallest interval of time I was going to experiment with on that particular plate, for the purpose of understanding here we will say 30 seconds. The plate would then be removed, rinsed with water, and patted dry with a paper towel. Next the solid ground would be added to a fourth of the plate--this would make the covered section the one that was etched for 30 seconds. After the solid ground dried the plate would be bitten for the amount of time that was need for the next section, for instance, if the next smallest amount of time you wanted to bite the plate was one minute, you would then bite your plate for 30 seconds more because it has already been bitten for 30 seconds. This was continued so that there were 4 sections on each zinc plate.

This was executed in a way that for both concentrations there was 1 plate with 0.5, 1.0, 1.5, 2.0 minutes, 1 plate with 2.0, 2.5, 3.0, and 3.5 minutes, and one with 3.0, 6.0, 9.0, and 12.0 minutes.

After the plates were made, they were inked with an oil based ink. A small amount of ink was applied to the plate and then pushed into all the grooves by scrapping a piece of cardboard over it. When the excess ink was removed with the cardboard piece, the plate was then buffed with a piece of satin cloth until the raised surfaces were clean. The inked plate and a sheet of water color paper were then rolled through the press.

After all the prints were dry the colorimeter reading were taken.

Observations and Data

3M Nitric Acid Observation and Data

Time/Plate	Biting Observations	Printing Observations	Lab* coordinates
0.5 min/#2	Compared to my fist practice plate, on this one I was able to get a much more even coverage, I also think I better timed the heating of the rosin	The first print was too dry, so the ink didn't transfer to the paper well. The second print I added more oil to the ink and it came out more bold.	+58.46, -0.50, +4.29
1.0 min/#2	Same	Same	+52.58, -0.32, +3.87
1.5 min/#2	Same	Same	+50.58, -0.18, +3.59
2.0 min/#2	Same	Same	+48.31, -0.26, +3.46
2.0 min/#3	The rosin coverage was not as consistent, thus the surface of the plate is inconsistent, however you can still tell a difference between the different areas.	Again, the first print the ink was either to dry or too thin--so oil was added to create a better quality print	+55.30, 0.00, +4.31
2.5 min/#3	Same	Same	+45.15, +0.01, +3.80
3.0 min/#3	Same	Same	+42.58, -0.01, +3.44
3.5 min/#3	The rosin didn't fully fuse to this part of the plate so it has the most inconsistent surface texture	The image is too blurry and inconsistent to read through a colorimeter	no results
3.0 min/#4	This Plate had a very even surface texture, it appears that there may have been more coverage on this plate	Although the bitten parts on the plate seemed small the depth created large wells for the ink which was transferred onto the paper creating darker tones.	+56.50, -0.16, +2.85
6.0 min/#4	Same	Same	+52, 97, -0.09, +3.45
9.0 min/#4	Same	Same	+47.05, -0.16, +2.85
12.0min/#4	Same. This are was hard to clean because of the deeply bitten areas	Same, one of the corners is much darker than the rest, but this did not effect the measuring	+42.14, -0.22, +2.92

1.5M Nitric Acid Observations and Data

Time/ Plate	Biting Observations	Printing Observations	Lab* coordinates
0.5 min/#7	The texture appears very consistent, however it is very difficult to tell the differentiate from each different time.	It is easier to tell the difference between the different timed areas. The print has darker and lighter lines through it--I think this the texture of the wool on the rolling press and is able to be seen on this plate because the pressure was too high	+68.61, -0.57,+4.41
1.0 min/#7	Same	Same	+61.35,-0.47,+4.51
1.5 min/#7	Same	Same	+57.79,-0.30,+4.22
2.0 min/#7	Same	Same	+50.84,-0.47,+4.10
2.0min/#8	The texture appears heavier on the edges of this plate	The print has the same lines as those described on the prints from plate #7	+55.85, -0.12, +4.87
2.5min/#8	Same	Same	+57.53, -0.11, +4.49
3.0min/#8	Same	Same	+51.42, -0.22, +4.27
3.5 min/#8	Same	Same	+53.60, -0.10, +4.04
3.0 min/#6	The areas that the times are different are still hard to differentiate between. Also the areas were not as rectangular because the solid ground was bleeding when applied to the plate	This print is of better quality than the prior two because the tension was not as high	+53.72, +0.14, +4.59
6.0 min/#6	Same	Same	+47.29, +0.06, +4.10
9.0 min/#6	Same	Same	+43.94, +0.07, +3.71
12.0 min/#6	Same	Same	+38.82, +0.08, +3.21

Visual Comparisons:

This is the 1.5 and 3M Nitric Acid Results for 0.5, 1.0, 1.5, and 2.0 minutes.The 3M is darker and has a rougher texture

This is the 1.5 and 3M Nitric Acid Results for 2.0, 2.5, 3.0, 3.5. The 3M results have a larger spectrum of tones but have a much less consistent texture.

This is the 1.5 and 3M results for 3, 6, 9, 12 minutes. Here it appears that the 1.5M nitric acid was able to create a larger range of tones while still having the more even texture. This could be due to the 3M plate having too much rosin on it.

Conclusions

The most difficult part of this project and where most of the error comes from is trying to keep the amount of rosin constant. It was also very difficult to keep the amount on the plate completely constant. This was my reason for overlapping some of the times that the plates were etched, it allowed me to see how constant I was able to keep the rosin coverage.

I concluded that the lower concentrated acid and the longer amounts of time created a smoother texture and a decent gradation of tones. However, this does not necessarily make it "better," the amount of time and concentration of acid used creates certain textures and tones that could be more or less satisfying depending on the opinion of the artist and the work they are creating.

Original Experiment vs. Final

My original plan for this experiment was somewhat vague to begin with--this is because I wasn't sure what I was working with, the amount of time required, and other things of this sort. In my original plan I intended on varying the metal; zinc and copper. The experiment with the zinc plates proved to take up all the allotted time for the project, thus the copper plates were not tested. Another thing that changed from the original plan was that the type of acids were not varied...the nitric acid on zinc plates was suggested in most of the literature I found, so I began my experimentation with this and I was able to learn more about aquatinting through keeping these things constant.