The Process
If you’re unfamiliar with aquatint etching, this page will walk you through the process.
The Basics
Intaglio is the printmaking technique where an image is incised into a surface and the incised markings hold the ink. Most intaglio prints are made using metal plates as the surface. I use zinc, but copper is also commonly used.
There are two main types of intaglio printmaking: engraving and etching.
Engraving (and mezzotint) is where the incised lines are made directly by hand - using various tools to mark your plate.
Etching (and aquatint) is where the incision pattern is made by a corrosive solution. Sulfuric acid, nitric acid, and ferric chloride can all be used, but with recent moves towards non-toxic printmaking techniques, most studios use ferric chloride. I, however, learned in a more old-school studio and I still practice using nitric acid.
To summarize - engravings are done by hand, but etchings are corroded with acid.
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The etched patterns in a plate will determine how much ink the plate can hold. The deeper the etching, the more ink it can hold, the darker the image will be once printed. In order to etch patterns greater depth, one must expose the plate to acid for a longer period of time. The images at the top right are guides that show how long a plate of zinc will have to be exposed to nitric acid when using a 10% nitric acid solution.
You want the acid to bite into the metal plate in a very specific pattern to achieve your desired image. In order to direct where the acid will bite into the plate, you can apply a variety of different acid-resistant materials to the plate, which protect the plate from acid corrosion when submerged. I use two different techniques, depending on the image I want to create.
For creating solid lines, a plate is coated in a waxy acid-resist called “hard ground,” that acts as a complete acid resist. The metal underneath is exposed by scratching through the hard ground (see middle image). Once the desired design has been incised, you can begin etching. The plate is submerged in a bath of nitric acid and left for a specific amount of time determined by how dark you desire the lines to become (see bottom image). This process is called hardground etching.
In addition to making solid lines, you can create varying shades to regions of the plate. To do this, you apply thin, even layers of finely powdered rosin to the plate. This acts as the acid-resist to create a stippling pattern in the plate. After the powder is applied to the plate, the plate is heated to adhere the powder to the plate, then the plate is submerged in acid. This process is called aquatint etching. We’ll get more into this later.
Proofing
It can be difficult to tell what your image will look like while actively etching. Luckily, you can print your image during some parts of the etching process to identify areas that need more work. This is called proofing. After my first round of etching, I stripped off the ground and printed it (plate shown on the left, and 1st proof shown on the right).
Aquatint
As mentioned, aquatint is an etching technique that aims to create a “stippling” pattern to provide greater tonal range in your image. This mimics the engraving technique of mezzotint. Once submerged in acid, the acid will bite down and corrode the parts of the plate not covered in rosin. The image on the top right shows a cross section of a plate with rosin.
Hard ground is still used to control where the plate gets corroded. Since many artists usually desire a larger tonal range in their image, the plate is submerged in acid for varying lengths of time. For example, after rosin is applied, the plate can be submerged for 30 seconds. It can then be retrieved from the acid bath and portions of the plate can be painted in hard ground to completely stop certain areas from corroding further. The plate can then be set in the bath again, this time for 1 minute, retrieved again, and painted to stop further corrosion. This is repeated several times over until the entire plate is covered in ground. The bottom two images show the amount of hard ground painted on the same plate between different intervals of being submerged (the hard ground is brown, and you cannot see the rosin on the plates).
However, corrosion does not follow a linear timeline. In other words, if you want an image that’s twice as dark, you cannot etch your plate for twice the amount of time. Instead, corrosion follows a more logarithmic pattern - corrosion slows as time increases. So, there can be a limit to how dark your image will become. As a work around, aquatint is typically done in “layers” where you apply rosin to plate, etch it for the maximum amount of time, strip it, and repeat the process. Since rosin falls onto the plate randomly when applied, each application of rosin will expose new areas of the plate to etch with each iteration. This will “layer” the markings, making the entire image appear darker.
Finishing the Etching
After each layer of aquatint, the image is proofed. The images on the left show the 1st and 2nd proof: before/after one layer of aquatint. The trickiest part of etching is that progress cannot be monitored every step of the way. Sometimes, a lot of etching has to be done before you get a chance to proof your image. To work efficiently, you need to separate an entire image into many tiny regions on your plate, where each region can only have one value/shade. Those regions must be etched cumulatively, meaning that from any intermediate proof, at least 2 or more regions will appear exactly the same value. So the real difficulty is in having to remember which region belongs to each value all over again, every time you etch. It's like paint by numbers, except you have no numbers and you may not have a clear template. Luckily, I was happy with my 1st layer of aquatint, and I continued to add 4 more layers until I was satisfied. The image below is my plate when I had finished etching it.
Printing
Once the plate is finished, you can begin printing. The press, ink, and paper must be prepared for the printing process. Etching ink is typically very tacky, so magnesium powder is mixed into it to make it easier to work with. The press will have to be set to the correct pressure setting. The paper has to be soaked in water for at least 10 minutes prior to printing (100% cotton paper is used to prevent warping).
The etched lines hold the ink, so you must “shove” the ink into the etched grooves. You start by coating the plate in ink, as shown by the top left photo. Heating the plate to 200 degrees F first helps since it melts oil-based ink and makes it easier to apply. Then, the ink is shoved into the grooves and wiped from the surface simultaneously with tarlatan cloth (stiff cheese cloth). The tarlatan is wadded up to create a shape that mimics the pad of a dog’s paw, and is pressed onto the surface of the plate in a twisting motion to shove in the ink and clean the surface. Once the image becomes clearer as more ink is wiped off, (as shown in the top right), the plate is buffed with phone book paper to clean off remaining ink from the surface. A plate that is inked and ready to print is shown on the bottom left. The plate is then run through the press, and the final image is pictured on the bottom right.
Editioning
The plate can be printed over and over in a process called “editioning” to create final images. A zinc plate will lose some detail the more it’s printed since it’s a soft metal going through hundreds of pounds of pressure when printed.
This piece was very special for me to create, and I’m so grateful for my time at Haverford College. I’d love to thank Hee Sook Kim for all that she has taught me, and my fellow 2021 Fine Art majors.
The 2013 photo the print was based off of, and the final print.
And the same place in 2021.
