Printmaking 101: Applying Liquid Ground to a Plate

Welcome to Printmaking 101 with Smidgeon Press!  This demo covers an essential process in etching: applying liquid ground to a plate. I decided to start making these tutorials to help my non-printmaker followers better understand the processes I use and talk about on this blog. Safety tips are bolded because they’re important!

Supplies for this demo:

  • degreased copper plate
  • newsprint (larger than the copper plate)
  • soft, natural-hair wash brush, around 1″ wide, that you can dedicate to using for ground
  • liquid hard ground
  • a hot plate (specialty studio equipment)
  • cotton rags (or if you must, quality paper towels)
  • a metal can with a lid to store the used rags
  • solvent-resistant gloves (nitrile or shop gloves)
  • mineral spirits
  • baby oil (mineral oil)

Etching is the process of removing bits of the plate surface using a chemical process (rather than carving directly into the surface). A plate is submerged into a bath of etchant (traditionally called the mordant or acid), which reacts with the surface and eats it away. To make an image on a plate, the artist has to be able to control where the mordant etches the surface. There are plenty of ways to do this, but the most common is by applying a ground to the surface of the plate.

There are several types of grounds, but the one we’re dealing with today is liquid hard ground, which I currently use most often in my work. Liquid hard ground is a mixture of asphaltum, wax, and mineral spirits. You can purchase pre-mixed stuff or make it yourself (you may have to test out some recipes before you hit on a successful one).

    1. The hotplate will need time to warm up, to go ahead and turn it on first. Make sure the temperature is set around 150°F (66°C). Anything higher than that isn’t necessary, and keep in mind that all of these materials are flammable or combustible.
    2. On a work table, lay down your piece of newsprint. Set your copper plate in the middle of the sheet, making sure you have enough room around the edges to hold onto without touching the copper plate. The newsprint will act as backing, to catch your drips (less clean-up!) and allow you to move your plate around without touching it.

      Copper placed on newsprint, with brush and a bottle of liquid ground.
      My newsprint is a bit bigger than it needs to be, but you get the idea. You can also see that this plate has an image on it. I’m applying ground so that I can add more lines to it. Many plates go through multiple etches.
    3. Carefully dip your brush into the container of liquid hard ground (or, if it’s easier, pour a small amount of hard ground into a dish dedicated to the purpose). I generally start by applying the ground to the center of the plate and work out toward the edges. The natural temptation is to to start at one edge, but that usually just results in slopping too much ground onto the newsprint and bleeding under the plate. It doesn’t really matter if that happens, but why be messy?

      applying the ground using a soft brush
      This part always looks so pretty to me. You don’t have to start in the middle, but I like to.
    4. Don’t worry if you can see brush strokes in the ground, but make sure there aren’t any bristles embedded in it (sometimes brushes will shed, especially if you get a cheap one). As long as the ground is relatively even and no bright copper is showing through, you’re set. Make sure that the hot plate is warmed up before you go on to the next step.

      Copper plate with wet hard ground applied.
      It should look something like this: mostly even, no copper showing. If you use a commercially-mixed hard ground, it may look a bit lighter and thinner.
    5. Pick up opposite sides of the newsprint, allowing the copper plate to sit in it like a hammock, and set the newsprint-hammock down onto the surface of the hot plate. Let it sit for a few minutes, and it really only needs to be a few. When the ground evens to a glossy, smooth appearance, remove it from the hot plate using the newsprint and set it somewhere to cool. Be careful: the copper will be HOT, so don’t set it on a glass surface or somewhere where it’s likely to be bumped or touched.

      The grounded copper plate wrming on the hot plate.
      Heating the ground gives you a smooth surface to draw on and helps the ground dry faster, but it cannot dry completely until you remove it from the hot plate. Remember, one of the components in ground is wax, which will stay soft and pliable until it cools.
    6. While your plate cools, clean up. Turn the hot plate off, make sure the lid is on the jar of liquid ground, and clean your brush, or it will harden. You can still clean it if the ground does harden in the brush, but it’s harder than when it’s still soft. This is a good time to put on your gloves and make sure you’re in a well-ventilated area. Pour a little mineral spirits into a dish dedicated to that purpose and gently swish the brush around in it, pressing to spread the bristles apart. Wipe the brush off on a shop rag. Repeat until most of the ground is out of the brush (you’ll never get it all).

      cleaning the brush using a rag and solvent
      To condition the brush and make sure it doesn’t harden, add a couple of drops of baby oil to the bristles and gently work it through, either with your gloved hands or on the rag.
    7. Make sure you put any dirty rags into a covered, metal container. Let your grounded plate sit for 30 to 45 minutes, then start drawing! Drawing through the ground with a tool will expose areas of copper, allowing those areas to etch.



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