Weston, cyanoytpe, curves, lights, and densitometry
Ohmagosh whataweek, One little snafu cost me 8 hours--I was working with students on curve calibration on Weston and Platine paper for cyanotype. I kept seeing major issues and finally figured out the discrepancy--I had printed their first calibration device on the Epson 4000 printer with "semigloss" setting (actually, my beloved TA did because that was what we did last year) and for some unknown reason I was seduced by the new printer driver's glossy 170 setting and I printed the next calibration device out with that, thinking that my TA could read my mind--in the future. I was assuming the usual adage "the further down the list you go, the more ink laid down" is true. It is not. This setting does not lay down as much ink as the 4000's semigloss setting. This is really important to know when printing diginegs! The only adage that was true was about "assume" making an ass out of "u" and "me". I learned the hard way. So back to doing all the work over again. The benefit was I printed about 20 prints on Weston and Platine side by side. OHHHH that's the REST of the story. Two light boxes, one Edwards 11x14 (F15T8BL 1/1/2 inches away from contact frame, one handmade large (F40T12BL 5 1/2 inches away). Again, I ASSUMED that the inch difference would cut some slack with exposure. Yeah right. Sandy King don't laugh. The small box is quite a bit slower than the big box, in fact, almost a stop. But what I found through myriad testings is a lot about cyanotype, and how it performs on different papers side by side, etc. The Weston paper is a great size--22x34, so it cuts to 4 11x17's or 8 8.5x11's. It is thin, and creamy ivory--not too dark. It LOVES cyanotype. So at about $1.50 a sheet including shipping cost, that brings the cost down per print to only maybe 20-40 cents. The speed of the paper in comparison with Platine (this is the biggest benefit of doing custom curve calculations) is faster. It is way more absorbent (and thinner) than Platine, too, but I ended up with an 8 minute exposure on Weston in the big light box vs. 10 or 11 with Platine in the same box, as a comparison. Camden is currently calibrating his platinum on it and has gotten deep deep blacks. Question--we only have a transmission densitometer here; is there any way to get meaningful data from that as to dmax of the platinum? If he subtracted transmission dmin from dmax is it a reliable and comparable indicator compared to reflection densitometry? I'd love to buy a reflection/UV one, but that is a loooong time coming. OH, and another student with the PDN system is currently calibrating modern ambrotype on glass. Our darkroom is bustling! Bottom line--it is paper worth buying especially if you teach alt process. Chris
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