Printmaking 101: Applying Rosin for Aquatint (Using a Rosin Box)

Printmaking 101: Applying Rosin for Aquatint (Using a Rosin Box)

Welcome to Printmaking 101 with Smidgeon Press!  This demo covers applying rosin to copper plate to create aquatint etchings, using a rosin box. This is Part 1 of 2, of my aquatint tutorial. Safety tips are bolded because they’re important!

Aquatint is a way of working with tone, so you don’t have to rely only on lines and step-biting to create variations in darkness on your plate (though Rembrandt never used aquatint, and some contemporary artists like DeAnn Prosia don’t either). Essentially, we’re going to cover a copper plate with teeny-tiny little specks of (in this case) rosin that will act as a stop-out (something that prevents the mordant from etching a particular area of the plate). This will allow an infinitesimal number of little pockets to get bitten (etched) into the plate, creating little “cups” where ink can stick during the printing process. How deep those cups are will determine how light or dark the tone will print, because deeper cups will hold more ink and shallower cups will hold less. With me so far? (This is usually where my new students give me a glazed look accompanied by some vague nods.) This is involved process, so bear with me.

Rosin is a natural substance: purified sap of pine trees. You can buy it as lump rosin, then pulverize it for use in aquatint (using a good old-fashioned mortar and pestle, or a coffee grinder–either way, dedicate them to the purpose; do not share food preparation items with your studio). While it is classified as non-hazardous, powdered rosin is dangerous to breathe in–it’s fine if you touch it, but the second it gets moist, it becomes intensely sticky. You can imagine the damage it will do in the moisture-rich, delicate tissues of your lungs, so wear a dust mask and eye protection when working with powdered rosin. Rosin can be cleaned up while dry by thoroughly dusting surfaces. When damp and sticky or melted, you will have to use denatured alcohol. Printmakers interested in non-toxic processes often eschew rosin for these reasons. You can read about methods for making aquatints without rosin here.

rosin box (sometimes called an aquatint box) is a piece of equipment used to evenly coat entire plates with rosin powder. I prefer using a rosin box because of how smoothly the rosin can be applied (and thus how even the tone in finished prints). I’m using a paddle-driven box, so there is no electricity required–just elbow grease. Fan-dispersed rosin boxes are also popular, but sometimes the fan blades get gummy and stick after a while. If you want to make your own, plans abound online, from super low-fi to ones that require more handiwork. Here is a visual diagram:

aquatint box design and diagram by Annamie Pretorius (AKA inugie).

As you can see, the box has a flap on the front that opens. This is how you will insert and remove your plate. Inside, there is a rack; this is what your plate will rest on. Below that, there is a paddle system that can be turned by a hand crank. The box I’m using functions on the same principle.

There are other methods of applying rosin to your plate, of course. Francisco de Goya applied powdered rosin by hand. He used variability in the size of rosin particles and areas of application to great effect (see: Los Caprichos). You can find a nice tutorial on that process over at Wretched Etching.

Supplies for this demo:

  • well-degreased copper plate
  • dust mask
  • goggles/eye protection
  • disposable, solvent-resistant gloves (like nitrile)
  • apron/protective clothing
  • denatured alcohol
  • shop rags
  • aquatint box (with powdered rosin inside)
  • backing board, larger than your plate (masonite works well; plastics have too much static)
  • extra piece of copper, bent in an “L”
  • hot rack/cooling rack with adequate space below
  • single-burner propane stove and matches (or reliable hot plate set at 250ºF)

Let’s get to it:

  1. First, make sure your plate is well and thoroughly clean and degreased. Anything on the surface of your plate (including fingerprints and solvent residue) with affect how the rosin melts to your plate.
  2. Be courteous! If you’re in a shared studio, make sure the rosin box is not already in use. If someone else’s plate is already in there, turning the crank will make a real mess of their plate. Peek inside if you’re not sure. If someone else is planning to use it at the same time and your rosin box is large enough to accommodate multiple plates, you can coordinate the next steps.
  3. Put on your protective gear: dust mask without question; for extra safety/sensitivities: apron, goggles and gloves. Remember, powdered rosin is dangerous to inhale and potentially harmful for any moist tissue. It is also messy, hard to clean up, and will dry out your skin.

    3M 8511 Particulate N95 Respirator. This mask is approved for non-oil-based particulates. Rosin is not oil-based, so we're good to go.
    3M 8511 Particulate N95 Respirator. This mask is approved for non-oil-based particulates (like rosin).
  4. Make sure the rosin box is tightly closed, then crank the hell out of that handle (nicely). Be sure to turn it in the correct direction; mostare designedto function well in one direction only. If you turn it the wrong way, the fan blades can get stuck, and then you’ll have a real mess to deal with.

    Heather McLaughlin fixing jammed blades in a rosin box. It's messy!
    Heather McLaughlin fixing jammed blades in a rosin box. The whitish powder all over her clothes and hair is rosin.
  5. Wait around 30-45 seconds. The heaviest (and thus largest) particles will fall in this time. Do the next step while you wait.
  6. Set your “L” piece of copper down on the backing board, then set your plate on top of the “L”. The lip that sticks up will allow you to pick up your plate later. You want to set your plate on backing board, rather than directly on the rosin box’s rack, because the powdered rosin will wind up being thinner at the edges of your plate if you don’t do this. (There is a great principle of physics in this, but I do not have the math for it. If anyone wants to explain it in the comments, though, I would love that.)

    Plate set-up for inserting in a rosin box.
    Plate set-up for inserting in a rosin box. If you look carefully, you will see that the backing board is set on a piece of newsprint. This is to minimize the spread of rosin powder around the studio.
  7. This is kind of tricky: the goal is to set your plate (and backing) inside carefully while acting quickly. As soon as you open the door, a could of rosin will waft out, and it will keep wafting out as long as that door is open and there is rosin to fall. You want it landing on your plate, not all over the studio! Carefully open the rosin box and pop your plate setup inside, ASAP.

    Get it in and shut the door.
    If you move too fast, you might accidentally slide your plate off the backing. Close the door quickly, but gently; slamming it can result in clumps of rosin falling on your plate.
  8. Leave your plate in for at least 4 minutes, and not more than 10 minutes. Leaving it in longer won’t hurt it, of course, but if other people are waiting to use the box, waiting longer is discourteous. You can remove your mask, etc. while you wait, but you will need to put them back on.
  9. Put your protective gear back on (if you removed them). Carefully open the door a crack andpeek in. If a lot of rosin is still wafting around, close the door and wait a couple more minutes. If the rosin is completely or nearly done falling, look at your plate. If it looks pretty evenly coated, move on. It should have a dense but smooth layer of rosin on it. Thereshould be no obvious clumps and no bits of shiny copper showing through. Troubleshooting:
      1. If the coating is too heavy (i.e., there are distinctive, irregular clumps of rosin or you can’t even see your plate), reach in and knock it all off your plate, then take your plate out. Clean it well with denatured alcohol (3 times), and start over.
      2. If the coating is too light (i.e., you can see too much copper), carefully remove your plate setup, remembering to close the door, and repeat from step 4. This can happen if you wait too long to insert your plate or if the rosin box is getting low.
      3. If the coating is just right, carefully remove your plate setup, remembering to close the door. Use the “L” piece to gently pick up your plate and slide a hand under. DO NOT TILT, JOSTLE, or BREATHE ON your plate (this is when that dusk mask is useful for something other than its intended purpose). That rosin powder is very fine, and this is the most delicate part of this operation. It’s VERY EASY to screw it all up, so be patient and careful. (Before removing my plate, I will turn off all fans, A/C, and cover any vents that blow air in my path, because I’m a perfectionist.)

    This is about right. It could be a little heavier, but I wouldn't suggest any lighter.
    This is about right. It could be a little heavier, but I’m satisfied.
  10. Walk your plate over to the hot/cooling rack (thisshould not be inclose proximity to the rosin box, which is kind a bummer, but necessary). Very carefully place your rosin-covered plate on the rack. Try to avoid “sliding” it, because that movements seemsto be where people tend to mess it up. (Alternatively, you can set your plate on your pre-heated hot plate, but make sure to have a good plan for how you will lower it on to thehotplate, and how you will remove it without burning yourself.)

    Whew! Getting the plate safely from the rosin box to the hot rack is the trickiest part.
    Whew! Getting the plate safely from the rosin box to the hot rack is the trickiest part. If you tilt the plate too much, breathe on it, or walk by a good draft, the rosin will move and clump on the plate.
  11. Rosin is flammable, and we’re about to light a fire. Exercise caution. Remove your gloves (if you’re wearing them). Grab the propane stove and matches. Turn the gas on low and light it. Slowly turn the gas up until you just start to see a few orange flames lick up out of the ring of blue flame (the orange flameshould not be consistent).

    If you have rosin on your hands, remember that it's flammable.
    If you have rosin on your hands, remember that it’s flammable.
  12. Holding the flame 2-4 inches below your plate, carefully and slowly move the flame around so that your plate gets heated evenly. Copper is a great conductor, but it should still take a couple of minutes (or more, depending on the size of your plate). Make sure your movements are steady and consistent; I follow a set pattern as I move around. Make sure you are actually reaching your whole plate, too; beginners often don’t move the flame far enough away from or close enough to their bodies,in relation to their plates. Side-to-side is less of an issue.

    This shows the movement pattern that I typically follow.
    This shows the movement pattern that I typically follow: back and forth, then side to side, repeat.
  13. While you carefully move the flame around, watch your plate. When the rosin melts, it will flash from whitish-yellow to clear. When it flashes clear, move the flame away and turn off the propane.
  14. The copper will be hot. Let your plate cool for around 15 minutes, or however long it takes to cool down enough that you won’t burn yourself when you touch it. The rosin, once melted to the surface of your plate, won’t be nearly as delicate as when it’s just powder, but you should still handle your plate carefully.
  15. You are now ready to etch aquatint (tone) into your plate.

Next up: step-biting an aquatint! I decided to divide the application of rosin and the actual etching of the aquatint into separate tutorials. While they are both steps in the same process, each part contains a lot of detailed steps and information. Please check back for updates. It will likely take me 3-6 weeks to get that new tutorial written. I’m sorry to leave you hanging, but you can send me encouragement via the “Thanks!” button below. Until then, happy printing.

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4 thoughts on “Printmaking 101: Applying Rosin for Aquatint (Using a Rosin Box)

  1. Do you ever post your step-biting aquatint tutorial? Great job on the rosin! We didn’t have access to a rosin box where I went to college so I’ve had to teach myself at home on my home made aquatint box and I’ve found your tutorial very helpful!

    1. Thank you, I’m glad you found it helpful! But sadly, I still haven’t done my step-biting aquatint tutorial. But if you’ve ever done step-biting with line etching, the principal is the same: etch, apply stop out and let it dry, etch, apply stop out, etc., so that you get darker and lighter areas based on the depth of the etch (and thus how much ink it can hold). The trick with aquatint is that the tone accumulates fairly quickly, but there’s a leveling off that happens over time. So I usually start by making a test strip, to see how dark my aquatint tones will be with the etchant I’m using. Generally to test a full range of tones, I go like this: 30 second etch, then stop out a stripe. 30 more seconds, stop out another stripe. 1 minute, stop out another stripe. 2 minutes, stop out. 5 minutes, stop out. 10 minutes, stop out. 10 more, stop out. 15 minutes, stop out. And, if I’m aiming for a black black, I do one more dip for another 15 minutes. Then I remove from the acid and clean the plate well with mineral spirits, then alcohol. Then I pull a print, and see how dark each tone winds up being. If you do it right, you’ll have examples of aquatint etches for: 30 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 45 minutes (which usually gets you to pretty deep black), and 60 minutes (which usually starts to show over biting, and you start to lose the black). I hope that’s not as confusing as I’m afraid it is! Making a test strip instead of just going straight to your final plate is tedious but will save you a lot of grief.

  2. Hi – this is a nicely written guide – thank you. My only concern – if I’m reading correctly – is that your using a particulate mask to cook the plate? wouldn’t you need a combination particulate/vapour mask?

    1. You’re quite right that a particulate mask will not protect one from any vapors produced from heating the rosin, and that using a particle and vapor mask is best-practice for safety. As long as you’re working in a studio with proper ventilation and avoid putting your face right over the plate while you’re melting the rosin (which you SHOULD NOT do), there isn’t much to worry about regarding vapors. If you’re working in a poorly ventilated area, you probably shouldn’t be doing aquatint with rosin, or anything that requires the use of solvents. Inhaling the powdered rosin itself definitely poses a greater risk to lung health than the vapors from heating, however. So a particle mask, even without vapor protection, goes a long way.

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