Studio Notes: Printing Relief With Cork Blocks

Blue Planet, fresh off the mini-jack press (click image to see detail)

Cork Blocks

I use cork to add a sort of an irregular "shimmer" to the color blocks in some of my newest prints. I used cork a long time ago for a print called "Fat and Happy" and have wanted to go back to it. I must say that it is frustrating to use and unpredictable at first, tough to carve, impossible to keep together and...well, that's enough bad rap!

I do like the results which is why I continue to use it. I get cork squares online or locally at craft stores and roll cork from fine woodworking stores; I think it's used for backing and dampening vibration.

I transfer key block to cork block using stiff transparency such as for projector presentations (well, before PowerPoint).
I print the key block onto the transparency sheet usually with waterbased ink. The transparent sheet is pinned down.
Then lift transparency, remove key block, slip the cork block into the registration jig, and transfer carved image to cork block.

I usually transfer to several blank cork blocks even though I will only use one.
This is because the cork is fragile and prone to crumbling and carving/cutting errors. Or I may just make two prints with different color schemes such as shown below.

 

 

The cork blocks are easy to cut with x-acto or craft knives and therefore very suitable for "puzzle" color blocks, where each piece of the puzzle is inked separately and assembled prior to giving it a once-through the press. The cork blocks are not easy to carve. If the cork is thin, I glue to a foam-core backing board to give it stiffness and the right height for printing--the same height, ideally, as the key block. If the cork is thick enough as in the tiles shown above, then I usually roll a thin layer of PVA glue all over the back to aid in holding together during carving and printing. I assume a layer of acrylic would work equally well.

The above block kept losing little pieces as I printed. The right-most block shows a big hunk missing after printing the edition of 46 or so. This print taught me to  not try to cut such thin pieces because they tend to crumble away from being taken apart and put together so many times. Cork is really more suitable for large areas.

Left most above is the cork block used whole, without splitting. Right picture are three variations of what happens during printing. When printing, cork acts like a sponge, whether using water or oil inks, and collects ink between the grains. This tends to accumulate and then pop out when pressure is applied so it gives very interesting effects. This also means that the cork block has to be completely cleaned off every ten prints or more often, otherwise the grain fills up completely and the grainy effect is gone.

You can also spritz the cork block or the paper (if using waterbased inks) with water and get an effect much like watercolor. After a few practice prints, the effect is actually quite consistent and controllable throughout the edition.

 

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