Scratchboard is my favorite medium at the moment. It is similar to wood engraving in that the image is in relief (raised above the surface). The image is created by removing the black surface to reveal the white underneath.
Scratchboard (a.k.a. scraperboard) is a very fine layer of kaolin clay spread onto a surface (either hardboard or paper) and coated with black ink. Uncoated scratchboard is available, if you would rather apply the India ink yourself, but it is difficult to achieve an even coating of ink. I prefer the hardboard to the paperboard because it allows for more delicate lines. The paperboard seems to absorb moisture, which creates an uneven finish on the ink, so that the lines chip and become sloppy. It is also very easy to scrape through the kaolin on the paper-backing and tear up the paper by accident. For professional artists, it is worth paying extra for the hardboard.
Colored inks are available (specific to scratchboard) but I love this medium for monochromatic drawing, so have not used or even experimented with them.
Anything sharp or abrasive can be used to scratch or scrape the board. This includes needles (upholstery or embroidery needles work better than sewing needles because they are stiffer. You can just tape them to the end of a pencil so they're easier to hold); sand paper, steel wool, Exacto knives, or scratchboard tools/knives. I like using the scratchboard knives, but the blades dull long before the first image is complete and they are difficult to sharpen. For a sharp edge, I recommend buying a Slice brand knife. The blade is ceramic and stays sharper than the steel blades. Also, Slice is a small company and you can get a HUMAN BEING on the phone instead of a robot and they're happy to answer your questions. It's important to support small companies whenever we can, but I digress...
clockwise from 3 o'clock position: a useless shape of a knife that is included in the two-pack at most art stores, a rounded blade, angled blade, Slice brand knife, scratchboard-specific pronged tool (descriptions below)
In the 3 o'clock position, a cupped knife best for removing roaches from coffee-cups and little else
a rounded edge knife blade, great for removing large areas of ink.
pointed knife blade, nice for variety of line thicknesses. *all of these replaceable blades go dull quickly and are very difficult to sharpen. Unfortunately, most art stores don't sell unpackaged blades, so they must be purchased two at a time-with the useless shape included- in a plastic package and twice the price. Single blades can be ordered online from a company like DickBlick.
Ceramic blade (by Slice products) shaped just like an exacto, but stays sharp much longer. Great for delicate linework. Better prices if ordered from the company, rather than the company named after a river.
A scratchboard tool with several tiny points, which gives a hatching effect. I found this tool fun to play with for a while, but decided that it was easier to control the hatchmarks made with the single blade.
Since it's a bit tricky to reverse your work, I find it best to do a drawing first and transfer it by using Saral paper. Leave an inch or so at the top of your drawing so that you can fold it over the top of your scratchboard and tape it down to the back. Then lay a sheet of Saral transfer paper down. You'll want the drawing taped in place so that you can lift it occasionally to make sure it's transferring well and that you haven't missed anything. The drawing lines from colored Saral's are much easier to lift than the graphite colored Saral or a pencil drawing.
Scratch or scrape away the light areas. Pay special attention to the direction of your lines and hatchmarks. The medium lends itself well to delicate drawings and every line counts! If you need to correct, I recommend a very thin (.005) Micron black pen. Please try to buy your art supplies at your local art supply store. It's important to be able to see the items in person and sometimes be able to test them or to talk to a knowledgeable employee. Trust me, it's a great loss when your town loses its independent art supply store.
The Saral transfer lines can be lifted up by using a removable tac adhesive, like Uhu. A kneaded eraser does not work, as it leaves an oily mark on the surface.
To fill in small, delicate lines a Micron pen works well. Try to use the smallest size to cover your line. An .005 works well for delicate lines. Keep in mind that drawing over a scratch is going to create a slight unevenness. Only the most particular artists will be bothered by this. If trying to redo a larger area, you may need to get some very fine sandpaper to even out the scratched area and then paint over it with India ink. The india ink will look darker and shinier than the rest, so be warned. I have read that spraying the drawing with fixative afterwards will even out the surface, but I do not use fixative for mine.
Above: Commission of Romulus and Remus in scratchboard, after an unknown 18th century painter.
I'm currently illustrating a book in this medium. The book is "Why Fish Don't Exist," written by the brilliant story-teller, Lulu Miller, familiar to many for her contributions to RadioLab and Invisibilia. The book will be released in late 2019 or early 2020 by Simon and Schuster.