WHAMOBASS T shirts – the ink thickens

This is the on-going story of my WHAMOBASS T shirts. It started last week with the color separations being prepared for screen printing. The total: eight colors including a luminance-based white.

The event is this coming weekend (it’s Wednesday today; I am delivering the shirts on Friday evening), and that’s no problem, as I am only purchasing about 120 shirts. The M&R Gauntlet press at Coudray Serigraphics is capable of printing several thousand shirts in an eight-hour shift.

This is the M&R Gauntlet screen printing press, taken from the second floor of Coudray Serigraphics in San Luis Obispo, California. The press is semi-automated, which means it prints automatically, but must be fed by hand. To see a video of the final press run, click here.
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The screens were prepared on Tuesday at the end of the day, and I arranged to be present today for the press run. When I got to the plant, the press was loaded with my screens, the ink was on each screen, and the press was being warmed to the right temperature. The viscosity of ink is controlled, in part, by its temperature. Mark Coudray uses the press itself to warm to screens and ink to get the job ready to print. On this job there are two inline “flash” dryers which heat the palettes on which the shirts are printed. The warm palettes move from unit to unit, and they let off heat, which is absorbed by the ink and the screen above.

Masking down under: Coudray applies a strip of tape to mask the register marks and labels after the press is made ready to print. In the background you can see the base of one of the Cayenne flash heater/dryer units that can be put in the press. Two are used on this job.
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Mark walks around the press with a handheld non-contact pyrometer to measure the heat of each palette, and of the screens as they pass by. He is waiting for the press to reach about 120° F before he begins to print my job. He finally places a sheet of non-woven Pelon onto a palette and announces that this is the moment of truth! The Pelon moves from unit to unit on the press, being printed, and flash-heated en route to the finish. At the end, Mark evaluates it – it’s in nearly perfect register on the very first impression. He gets out a loupe and looks closely; the yellow may be a half-dot out of register. He makes a small adjustment to the yellow to fix that. He hands me the proof, and we both step back to evaluate the job.

This is the orange printer, the screen carries the image in a porous area of an emulsion coating the screen. The press floods, and the prints with the orange color using pneumatic devices to drive the flood bar and the squeegee.
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It looks pretty good – very good indeed; I am not surprised, nor is he. What has us both concerned is a moiré pattern in the blue sky just above the horizon. It’s noisy, and it’s obvious. We stop, and confer with Rob, who made the screens. Mark decides to re-make the screen with a different mesh of screen printing fabric. Rob walks off to do that while Mark and I look at the job that has just finished printing. It’s a multi-color shirt for a jazz festival in northern California. Beautiful art, beautiful printing – it’s flawless. I take a couple of photos before the shirts are packed to go onto a waiting UPS truck.

About ten minutes later Rob comes out of the screen room carrying the new blue screen; I watch as he inks it and gets the press ready to run Proof No. 2. Screen printing isn’t like offset printing – you can’t run actual shirts as proofs, as that’s too expensive. So, we run another sheet of Pelon. Again, the moiré is troubling. Mark decides to make new film, first conferring with Tami – who made the art ready to print – and then making an adjustment to the gradient of the light blue color. Then Tami sends the job to the SelectSet imagesetter.

Mark Coudray reviews a proof shirt that was run to test the corrected light blue printer – which had exhibited the moiré pattern. In the end, he decided to change the color to a stochastic patter, and to try again in the morning (Thursday). There is still one day left over.

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Mark and I go off to talk about audio recording and blogs and online programs. Mark has a very successful program called Halftone Mastery, where screen printers from all over the world watch online presentations by him on how to do process color (and more!) printing on garments. His program is doing very well as screen printers work to produce better work, and want to learn from the master how to make extraordinary screen printing.

Minutes later, the new film falls out of the processor, and we are working with Rob again to expose another screen. When that one is dry, it goes on the press and is inked with the light blue ink. The moiré has not gone away, alas, it has just moved from the highlight area up into the midtones of the sky. So we stop for the day.

Mark will make another blue printer tomorrow morning using a stochastic screen instead of conventional halftone dots. He says this will solve the problem on press. So the shirts are not yet printed, but they will be printed tomorrow.

Stay tuned!

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