Advanced Lithography Techniques: Etching Water Tusche Washes
What is Tusche?
Tusche is a suspension of grease particles in either water or solvent that gets applied as a wash in the lithographic process. The traditional recipe of tusche includes a combination of wax, tallow, soap, and lamp black. As the tusche dries, it deposits grease particles onto the surface of the matrix in a reticulated pattern, a characteristic mark known in lithography.
Stick Tusche
This is the most economical form, particularly for shared shops. Can be used for both water and solvent washes and has a low risk of contamination. To mix, scribble the stick onto a clean and dry ceramic plate until the surface is completely covered. Add water and mix. Pour the tusche into a separate container, dry the plate, and repeat until a concentrate is formed.
Paste Tusche
Easier and quicker to mix up in comparison to stick tusche. Ensure the cans are explicitly labeled H2O or solvent, and that no mineralized water or gum contaminates the can. To mix, add the desired amount of distilled water to the can and gently mix until a concentrate is formed.
Importance of Distilled Water
When mixing your washes, ensure that the water being used does not contain any minerals. Common minerals found in tap water can interfere with the wash. For best results, use distilled or filtered water.
Avoiding Other Contaminants
To avoid other common contaminants like gum arabic, keep separate brushes that are solely for tusche. To store your wash, keep it in a container that is not used for anything else. Glass containers work best for me, but a plastic container with a lid will work as well.
Mixing the Concentrate
Using a short, stiff-bristled brush, slowly incorporate the water into the tusche to avoid air bubbles. Mix until a thick concentrate is formed. Use a scrap piece of paper to test. If you can apply a completely black stroke with no streaks or grey tones, your concentrate is ready. You can then dilute it to whatever you’d like. Generally, I don’t like to go under 25% tusche to 75% water. Any lighter than this may not be able to withstand etching, even if it is etched with just gum.
Cleaning the Stone
Before you begin to apply your wash or any other drawing material, make sure to clean and dust off your stone thoroughly. Any residual dust left on the stone from graining may prevent your drawing material from fully adhering to the stone.
Applying the Wash
Make sure that when you’re applying the tusche, it’s “puddled.” If it’s applied with a thin or light stroke, there may not be enough grease there for it to withstand etching, and you won’t get reticulation. Tusche works best if you don’t move it around or disturb it too much once you apply it, much like watercolor. Also keep in mind that a gum arabic mask will not work to keep areas white, since the water in the tusche will dissolve the gum. Instead, use an ammonia-free liquid latex or remove the area later.
Stone Colors and How They Take Etches Differently
Light Grey/Grey stones are best for washes. Keep in mind that grey stones are harder and can usually handle a hotter etch. Yellow stones are softer and like a hot etch but should be etched with less acid for longer periods of time for best results. It’s also important to note that yellow stones love grease, which means that the concentration of tusche should be lessened to help it from filling in later.
Beginning the Etching
Apply an even layer of both rosin and talc. Rosin acts as a resist against the acid that we’re applying to the image. If you don’t rosin your image, you’re far more likely to burn things out. Uneven applications of rosin can lead to uneven etches. Talc is equally important. There is a slight electromagnetic gap between the drawing material and the gum/etch, since grease repels water. Adding talc removes this gap and prevents the image from growing.
Preparing the Etches
The etching process requires that you be flexible and adapt as things go along. The etch strengths you think you may need now, could very well change once you start etching depending on how your stone reacts. From shop to shop, the amount of acid may vary as well. This can depend on what kind of dropper you’re using for your acid, as well as the temperature and humidity in your workspace. It’s really a matter of persistence and trying things out to best suit your needs. There isn’t one way to do things, and that’s important to understand, especially in litho.
It’s important to understand the characteristics of the tusche you are using in order to etch properly and successfully. A common mistake made when etching tusche is reading the value of the pigment on the stone and etching according to that. Instead, the etch should be determined by the amount of grease in the wash. A wash may look light on the stone, but it may be greasier than it appears.
If you apply gum to a light wash, but the gum immediately gets pushed away from the image, that’s an indicator that the wash is greasier than it appears, and should be etched more. If there is a greasy halo around the wash, this is also an indicator that there’s a significant amount of grease. If the reticulation is very close together or solid, that is also a sign that it should be etched more. More open reticulation means that it can be etched lighter. Also remember to consider which brand of tusche was used, as grease contents can vary from brand to brand and affect how it needs to be etched.
To have a successful etch, we first need to understand a little about etching theory. There are 3 different factors to consider that will affect the etch. Acid, time, and quantity. First, is acid. How much acid is in the etch? The more drops/lower the PH, the stronger the etch will be. Secondly, is time. How long is the etch sitting on the image? The longer the etch sits, the more it will etch. But do keep in mind that an etch in stone lithography expends itself after 3-5 minutes and should either be replaced or cooled down with gum after that point. Lastly, is quantity. How much etch is going on the image? A bigger pile is going to have more of a chance to etch than a small pile. Taking these factors into consideration, there are different approaches to etching effectively. For example, you can do a hotter etch with a small quantity for shorter periods of time (say 30 second intervals). You could also do lighter etches with a higher quantity for longer periods of time. Try things out. Do some tests and find out what works best for you and the specific needs of your image. Everyone is going to have a slightly different etching style.
Begin by applying your weakest etch over the entire stone. You need to cover the whole stone to establish the adsorbed gum arabic layer in the non-image areas that will attract water when you sponge later. Your weakest etch may or may not be straight gum arabic. Once you have applied the weakest etch, take a minute to reread the grease content of your washes. This may again change the etches. As you increase your etch strengths, you may need to do spot etches with a brush on specific areas that need more of an etch.
If you pay close attention while etching, you can see subtle reactions that the stone is giving you. Etching is a lot like having a conversation with the stone. You can see the surface of the wash change as you etch it, becoming almost like a topographical map. For very dark washes, giving it a little bit of a hotter etch can be helpful as well. When strong acidified gum reaches limestone, it foams or bubbles. This is a sign that your etch is hitting stone and etching thoroughly. Be careful, as this is a really easy way to burn out weak image areas if you’re not careful. The second bubbles start to form, immediately remove the etch and cool down with gum. Another common mistake when etching tusche is getting very visible burn marks on the washes. By puddling the etches through a loose layer of gum, you can mitigate and prevent those burns. When cooling down or removing etches, pat the excess etch off and don’t swipe. Keep a nice stash of gum sponges nearby if you have large or complicated images. Paper towels or shop towels also work.
If it helps, set a timer. Take it slowly if you need to, cooling down with gum often. Work in sections if you feel overwhelmed. Take pictures. Take notes. Use the tools at your disposal if you feel like it would help. Again, everyone’s style is slightly different, and there’s no shame in that. It’s always better to approach this stage with patience and confidence. This process takes lots of practice, and just know that with more experience, you will get better. The most important thing to understand is that you shouldn’t get discouraged when something goes wrong. It’s likely that the first few times that you try this are going to be rough. Just keep at it.
A good buff with gum once you’re done etching is also crucial to a successful etch. A streaky or uneven buff can create a streaky or uneven image. It can be hard or impossible even, to wash out later. To have a good buff, have at least 2-3 cheesecloths on hand. You may need even more for large stones. Borders first, vertical strokes, then horizontal. Switch to a fresh cheesecloth, do another round of vertical and horizontal, switch to a dry side and buff in small circles.
Let the stone rest for at least an hour. This will help the fatty acids in the drawing material to react with the limestone for an optimal amount of time, converting both into an insoluble soap that helps the image stabilize properly.
Always start with a freshly scraped leather roller. Scrape both ways to ensure that you’ve gotten as much old ink off as you can.
Prepare the ink and roll out your slab
For rolling up, you usually want to start by using a medium-bodied ink like Shop Mix. Here at Tamarind, we usually mix up our own version. Sometimes, Shop Mix right out of the can is too loose and greasy for washes and can overwhelm them easily. You can mix your own ink by combining Charbonnel’s Noir à Monter with Crayon Black. A good starting point is 3 parts Crayon to 2 parts Monter. Another option is to add a few drops of #00 Varnish to the crayon if Monter is unavailable in your shop. It’s a lot easier to gradually add grease than it is to try to take it away from the stone. A stiff, lean slab is a good way to start. You can always modify this as you go.
Wash out like normal
If your drawing material is stubborn and not lifting off, let the solvent sit for a minute or two. Let the solvent do the work and be careful not to scrub the image out. Buff in a layer of asphaltum. Make sure it’s completely dry before proceeding.
Buff in a layer of asphaltum until streak free and dry.
At this point, the stone is at a very vulnerable state. Asphaltum on its own is very susceptible to burns. Make sure everything is set up in order to start applying ink as quickly as possible. When applying water, do the borders first, then move quickly into the image. Use plenty of water and get it off as quickly as you can to avoid getting water burns in your image. Immediately begin rolling ink onto the image.
Keep rolling until the image is full. This means that you want to see the black of the ink, and not any brown. If you can see brown, that means that the asphaltum is still exposed and not covered by a protective layer of ink. This could lead to burning your image during the second etch. If your image doesn’t want to take ink, loosen your ink slightly. The looser your ink is, the more grease it has, and will help the image fill in better. The opposite goes for stiffer ink. The stiffer the ink, the less grease. A stiffer ink is good for keeping delicate or light marks that are prone to filling in.
Sponge and dry the stone.
Rosin and Talc as per usual.
If your image rolled up exactly how you wanted, repeat the same etches as you did before. If not, modify your etch strengths slightly. If the image filled in, you’ll want to increase your etch strengths. If the image is too light, you’ll want to decrease your etch strengths. But be wary of too much of a change in the etches. Too high of a jump in the etch can increase the likelihood of creating burn marks in the image. If the image burned out at all, don’t worry.
At this point the stone can be counteretched in order to add back anything that was lost during the first etch.
The harsh reality of tusche washes is that they will likely need extra etches to be stabilized before they’re ready for the press. The more you can open and close the stone, the better. This can mean doing 3 or more etches on your stone before you begin to edition. You can get away with proofing one or two prints with fewer etches if you’re short on time, but it’s certainly not sufficient for an edition.
Press Etches
Even after etching multiple times, your wash may still want to fill in as you’re printing, especially if you’re doing a larger edition. This may mean that you need to do a press etch as you’re editioning. If you notice that a certain area is starting to fill in a bit, don’t wait. Make sure the image has a protective layer of ink and immediately apply a light etch. Don’t overdo it though, as the etch should be applied and removed with a clean gum sponge quickly. You won’t necessarily see a difference until you start rolling again. Proceed as normal. If your edition is larger than 10, anticipate doing some form of press etch. You can also modify your sponging water to aid in keeping the image stable. Adding a touch of gum into your water can give your stone a little bit of an etch to help it stay where it needs to be.