A bit of supporting text:
A rainbow roll occurs when two or more colors are rolled up on the same roller. The colors eventually blend together where they meet on the roller.
Using a blended roll with oil based inks can simulate the effects of bokashi in moku hanga printmaking. It can help to add depth and subtle shifts in color to your image, especially when printing multiple block images.
–Paper (anything typically used to print by hand)
-Proofing paper (double the amount of newsprint or other paper typically used)
–Rubber Brayer or Roller (MUST be wider than the image area you are going to roll up)
-Printing press or Baren
-Two or more Ink knives (One for each color)
Step 1: Getting the Ink Ready
Separately mix up two (or more) colors of ink. Work inks for a few minutes to get an idea of the flow of each ink. It is easiest to do a blended roll when all inks have similar flow. You can add Magnesium Carbonate or Oil to make the colors more similar in viscosity and tack.
Step 2: Rolling out the Ink
When laying out ink, think about how much of the image each color will cover. There will be a mixing of both colors in the middle, but one color can take up more room than the other.
Place the brayer on the ink slab, and smear one ink from the end of the brayer to the middle. Be sure that the ink starts out heavier near the edge of the brayer and thins down to a minimal layer near the center. Do the same with the other color, starting near the opposite end of the brayer. Don’t actually touch the first color with the second ink knife.
Begin rolling up the ink with the brayer. A few slightly diagonal passes (about 5 to 15 degrees) can be done, but most passes should be straight without flipping the roller or turning it 90 degrees. The straighter the roll the more even the edition will be.
Step 3: Inking up the Block
Once the colors start to blend in the middle and there is an even amount of ink across the brayer the block can be inked. Carefully decide where to place the brayer to begin inking. With every additional print maintain the same brayer position when inking. If the roller hits the block in a different position the colors will eventually blend together, muddling the blended roll. It is helpful to lay out the direction you are going to roll each time by marking where your block will sit, and then creating tape marks that outline the ends of where your roller will travel.
Step 4: Proofing
More proofing is generally needed to get to a stable ink layer with a blended roll. The colors will blend more and more with each proof, so using the first proofs as a guide for the final print is ill advised. It is a good idea to see how the first couple proofs look (as with any print), and then make adjustments by adding or subtracting ink from one end of the ink slab.
Step 5: Printing the Edition
Once the ink slab and block are a satisfactory blend of colors, edition printing can begin. Printing will be the same as with any block printed with oil based ink and a baren, but take greater caution with rolling and ink adjustments as the edition progresses.
If the colors are beginning to blend too much, portions of the ink slab will have to be scraped away, or simply begin a new slab. If this is done it will require more proofing to get back to the original blended roll.
Tips and Troubleshooting:
After a blended or rainbow roll has dried for a day or two you can come back with the same colors but roll from another direction. This will allow you to achieve a mixing of colors or value that is doesn’t follow one linear direction.