It’s hard to kill a technology and keep it buried. “Thatching,” for instance. Once there was enough thatching going on in Britain to make “Thatcher” a common name. Today, building a roof out of wrapped-up marsh reeds is an aberrant thing to do; it houses vermin, it slowly rots, it smells funny, it catches fire… But thatch has returned in triumph to downtown London.
Shakespeare’s Globe Theatre is back, from a vampire death of three and a half centuries. It’s built on the same spot, and in the same way, as the Bard knew it – except for certain unavoidable changes. The walls are much stronger and safer. The stairs and seats aren’t so cramped and hazardous. And all the thatch has been carefully chem-proofed, so that the thatch can’t burn the place down again, which is what happened to the Globe Theatre last time.
That’s very odd, yes. But the charming tale of thatch is as nothing as compared to the strange evolution of an old printer’s darling, “lithography.” Lithography is two hundred years old. Utterly non-digital, it’s all about limestone, grease, ink and acid. Jules Cheret and Toulouse-Lautrec used to hack this stuff. Fine-art lithography, the traditional craft that’s still done with ink sponges, rollers, wooden scrapers, and big iron squeezers, has never quite died out – even though its fumes are now classified as health-hazards. The ancient honored craft is still hanging in there, wheezing for creative oxygen in the iron lungs of arts colleges and collectors’ groups.
However, in a recent issue of Nature magazine (8 April 1999), lithography rises again, in a new, ultra-high-tech guise!
In an article called “Micro-Printing With Crystal Inks,” lithography leaps boldly to the forefront of technological advance! The elderly craft has found a new home in the forefront of academia and industry, in the Harvard chemistry department, and the labs of Lucent Technologies in New Jersey.
This latest heir to the gooey press of Lautrec is a very peculiar device. It’s still a little litho press, though. The trade still talks just like the old lithography: it’s got “masters,” and “stamps,” and “resists,” and “ink,” and “registration,” and multiple copies peeling off, just like an avant-garde poster of Moulin Rouge can-can dancers.
Except, these litho prints are small. They are very small. We’re talking “topographic features” (or maybe “typographic features”) that are three to fifty micrometers across, about .0001 inch. This is the size-range of circuits on microchips.
Of course, people have been printing “printed circuits” for quite some time now. Semiconductor manufacture has a lot in common with traditional block printing and lithography.
However, this new lithographic process doesn’t make silicon. It makes calcite crystals. The new technique has been inspired as much by biology and seashells as it has by electronics and silicon.
The goal here is unprecedented sophistication and control of crystallization. You need processes that can be repeated with total fidelity and high quality, and cheaply, too, with big economies of scale. Just the way you make computer chips, in other words. Just the way you print books and magazines.
So how do you make a litho crystal print? First, naturally, you make the master. This is always the expensive part. In the world of micro-lithography, they’ve tried all kinds of stunts to carve the printing surface: microphotographs, epitaxy beams, interferometers, little tiny needles; you can even cut-and-paste patterns off of the skin of bacteria.
In the case of the “crystal ink” printer, the stamp was a test-grade silicon wafer. It had a layer of gold and silver deposited on it, with an electron beam evaporator, in a hard vacuum. (As you can see, we’re working pretty hard already, but that’s just the block-mount for the press.) The master pattern itself was created by casting and curing some rubber-stamp-style plastic goop, “poly(dimethylsiloxane).” The chosen stamp pattern was just a monotonous bunch of little round dots, but that’s because engineers have no taste.
So now we finally have our master stamp pattern. Time to print some crystals. We slather the plastic stamp with a chemically active self-assembling monolayer of “crystal ink.” This ink sticks faithfully to the bumpy stamp design. So then we stamp the graphic onto another delicately prepared metal surface, where it peels away and sits there, a lovely little rubber-stamp image.
Then we put the master stamp away. We now turn our attention to our brand-new stamped copy. This rubber-stamped copy is a superclean layer of crystal-ink on bare metal. We fill in the blank parts of the design with a layer of neutral goop. It’s just like wetting-down the surface of an inked litho stone before you stick the paper on.
Then, we gently wash the copy in a saturated solution of calcium chloride. We give the saturated liquid a healthy shot of carbon dioxide gas, i.e., soft-drink bubbles. This causes the dissolved calcium chloride to crystallize onto the graphic.
Then you dry it out, and presto: it’s a litho fine-art print! You started with a “stamp” and “ink,” but now you have something like mother-of-pearl.
The next step forward (for these hard-working materials-science experimenters) is to make a solid, totally controlled sheet of seashell crystal. You could dope the crystal with all kinds of interesting, active impurities, and you would have a new kind of ultra-sophisticated, ultra-controlled ceramic. You might make new semiconductors, or superhard coatings, or smart coffee-mugs, or heaven only knows. Industry Marches On. Nobel Prizes tumble out of Stockholm. There is tenure, and stock options, and product roll-outs. Life is rich and full.
However. Co-optation of technology goes both ways. Lithography is inherently arty, and though scientists have a nice firm grip on it, it’s still very much up for grabs. Art always oozes in at the corners. What about those little graphic dohickeys that engineers at chip-fabs secretly draw on their silicon chips?
Silicon as a graphic medium is rather dull and ugly stuff. Calcite is sleek and beautiful. If we get into a technical position where we can litho and print big colored sheets of mother-of-pearl, then some artist is certain to steal this new form of lithography back. Then we’ll need crystal ink, and crystal pigments, and crystal graphics standards, and crystal pixels, and crystal seashell fonts. We won’t be doing lithos off limestone any more – because we’ll be doing lithos oflimestone.
Yes, that’s farfetched. I admit it. But the richest guy in the world right now sells programmed road-maps for invisible scratches carved into fused sand. Ask Shakespeare what he makes of that, if you find him up in the peanut gallery.