Digital Negatives for Silver & Platinum Printing - UPDATE
2002-08-19 by mkravit
Folks, I am now writing an article on making digital negatives utilizing Epson 1280 and Epson 10000 printers. I promised everyone here that I would update the list once I was a bit further along. Well, here it is. I am now making digital negatives and printing them in platinum and silver. I ran into a major issue with what I was calling "digital grain", That is my platinum prints showed a noted increase in grain. Not really a problem when making 24"x24" negatives, but a real problem with small 5x7 or 8x10 prints. Finally I linked the problem with the Epson driver. With the combination of inks that I find works the best, the Epson dither would create digital artifacts (mabe not the right term), or perhaps optical artifacts that manisfested themselves as what appeared to be increased grain. I finally solved this problem and also the problem of smooth tones in sky areas by utilizing the ImagePrint RIP. I will go into all of the detail and my procedure in my article. The neatest and most exciting aspect for is that I do not have to use a restrainer (contrast agent) in my platinum coating. Contrast agent degrades the platinum image by clumping the grain into ugly nasy groupings. In my process, it is no longer necessary to use Potassium Chlorate or any of the dichromates to obtain contrast control. Another issue with which I was concerned is that of fading of the negative when exposed to very strong UV light. My UV exposure unit utilizes 12 40watt VHO UV tubes. My contact print times are running 150-220 seconds. I was concerned that after perhaps 6- 10 prints the density of the digital negative would be reduced enough that the print times would be affected. I am finding that with the dyes that I am using (dyes seem to make smoother digital negatives in my experience) seem to initially shift toward red under the strong UV light. Once exposed the first time, they actually gain a slight amount of density and them maintain their density for subsequent printings. once my testing is finished, i will post the sensitometry to support this position. As many of you know, platinum printing requires significantly more density than does the silver process. Since the dyes tend to shift toward red after exposure, the reddish color acts to build density. I will keep everyone updated. Mike