...sort of.

So here's a little progress update.

I got 25g samples of

4-Diazodiphenylamine/formaldehyde condensate hydrogen sulfate zinc chloride complex (CAS 68988-17-0)


4,4'-Diazidostilbene-2,2'-disulfonic acid, disodium salt, tetrahydrate (CAS 2718-90-3)

from Secant Chemical about 2 weeks ago. They were shipped in heat-sealed foil packets, each in a zip-top bag, in a bubble-wrap mailer. They were shipped UPS 2nd Day Air from Massachusetts to Washington State. I am keeping them stored in the refrigerator.

Based on this tip from CMB, I mixed up my standard recipe of (high-relief) glop, and added the same amount of diazidostilbene sodium sulfonate as I would have used dichromate (approx. 2 mg / in^2 of tissue).

I'll get a scan of the step wedge up in a day or 2, but here's what I've found so far:

--It's about 1/2 to 1 stop slower than the comparable dichromate-sensitized tissue, but with a much longer exposure scale (about log 3.0). This is 600-800 units on my NuArc. 800 units is about 20-25 minutes, which gets to be a little hot.

--I'm not sure this is suited for high-relief tissues, as there were a fair number of micro-bubbles, more and larger in the darker areas. I belive that the azide compound gives off nitrogen when it decomposes, so that might be causing it. In the lighter areas (thinner gelatin layer), the bubbles were less-pronounced. My next test will be with a thinner, more heavily-pigmented tissue.

--An un-exposed tissue was exposed to incandescent light (2 x 100W in a 6x9 foot room) for 2 hours without any noticeable fogging, so it's probably safe to handle dry tissues without use of a safe light. CMB has alluded to the compound being more sensitive in solution (link), so I don't know about making/pouring the glop. (For this batch, I used a red safelight).

I do have one unknown, still. I would prefer to have more speed on these tissues. If the diazidostilbene sodium sulfonate behaves the same way as dichromate, then I've got a problem. More sensitizer = more speed, but as the exposure scale goes beyond 3.0, it becomes very hard to create negatives for this process, even with litho film or xray dupe film. Hard-dot screened imagesetter negs might work, but not on this forum .

I'll be sure to post more as I learn more.