Last night I made a small batch of emulsion for the latest matrix coatings. I included 3 drops of both FD&C Yellow 5 & FD&C Red 40 to act as extinction dyes. Yellow 5 (acid yellow 23, tartrazine) has peak absorption at 422nm and Red 40 (Allura Red) at 504nm. If anyone has spectral data on the red, I'd love to see it, as it is not in the Sigma-Aldrich handbook.
I don't know how effective this amount will be; the gelatin is red, but not exceedingly so. I have no idea what Kodak's matrix film looked like with the extinction dye, or how dark it has to be. We'll see...
Regular Matrix film was yellow. It used Tartrazine alone.
As a side note, Pan Matrix film was black and used a soluble dye. Some claim that carbon was used to form the black and it remained. Well, here is the extended story as far as I can figure out. The early Pan Matrix was black and the dye washed out. This was so Pan Matrix and Matrix images were identical and could be compared. It allowed for easy reading of the gray scale that was included. Also, Carbon Black was made from burning tallow which imparted some harmful organics to the carbon mix. So, it was not used. In later years, pure Carbon Black was made available primarily for the image transfer products, and this was used as a permanent black image in Pan Matrix film along with the silver image.
I chose to add FD&C Red 40 kind of as an afterthought, since tartrazine's near UV absorption isn't great.
I had no idea pan matrix film was black; that's fascinating. Was the coating completely opaque? Thanks for.. the rest of the story ;)
Pan Matrix was panchromatic. It therefore had to have a black acutance dye just as tartrazine was the acutance dye for a blue sensitive film. It was not opaque, but rather translucent like Matrix film.
Sure, that makes sense. It got me thinking though that a black pigment might have higher tinctorial strength and would have the added benefit of making the DCG matrices easy to identify.
Glad to know it was translucent, and yet still effective in its purpose.
I think carbon printers need to appreciate how easy this process would be to do, even with their existing glop. In fact, a matrix could be made in the typical transfer method onto a gelatin-free support. The gelatin would fog highlights as it would imbibe some dye.
Can't a carbon transfer more or less stick to any smooth surface? This would alleviate the need for a specially subbed product like the Estar Melinex.
Furthermore, it might result in sharper images; not having to expose through the base.
Just a thought...
Exposure through the base is needed for any image that must adhere to the base. Exposure from the emulsion side is needed if one is to transfer the image. The acutance dye is needed to insure sharpness during exposure which is not materially decreased by exposure through the base.
With pan matrix, you could do an easy test strip with the red filter. You processed it and then slapped it onto a white tray to judge density. Because the emulsion carried tone, you could make a pretty good assessment of exposure for another test in 3 color that you would print. This same exposure test wasn't required with chromes because your chromes had so little exposure latitude.
H-burgers, you mention fogged highlights.This was an issue that was solved with a solution of Calgon water softener in the first rinse when printing. This made a huge difference in highlights and was (for most commercial labs) a default correction.
Exposing through the base + exposing sep negs through masks + stacking assorted post masks on the negs + making multiple incremental exposures with a register carrier -- all these things effected sharpness.
This is why point source lights were used with long focal length lenses (a 105 apo-nikkor was the industry standard for 35mm). Some of the challenges were minimizing diffusion, minimizing internal enlarger reflection, minimizing chromatic aberration.
PE, I've been thinking of the extinction dye as necessary for creating a thin relief, but does it also enhance acutance? I can see how that would be an added benefit!
Dewey, thanks for sharing that about the Calgon. Do you recall (roughly) at what concentration it was used? The chemical I was told helped with fogged highlights is sodium-hexametaphosphate, which also appears to be a water softener.
105mm on 35mm must have made for a tall enlarger. Did you also use wet-mount carriers and the like? The surgical precision of dye-transfer labs is somewhat intimidating to me. I hope I can get by with slightly less.
I plan to get into densitometry soon and really make sense of the system as a whole.
I seem to remember that we mixed Calgon according to the instructions on the box and then added 5 - 10 mls per liter of first rinse depending on the amount of effect required.
Tartaro used the apo-nikkors on 8x10 Fotar enlargers modified with 5x7 Durst condensors and a low voltage pointsource. The chromes were suspended in mineral oil between glass.
Bob DeSantos had a lab in LA and he modified old Leitz Valoy enlargers for seps. If you haven't seen one of these, they have a very precise focusing system - more like a camera lens.
here's a picture: http://store.valueweb.com/servlet/vi...aloy-II/Detail
Bob wasn't too worried about his gear being pretty, so the point light was housed inside of a coffee can that has fitted to the Valoy. Since you're (typically) making your seps the same size for every job, the enlarger is locked and braced to the wall. I even had enlargers braced to a 4" pipe that was sunk into a concrete floor.
Originally Posted by Photo Engineer
Hi Ron and Chris - I just happend across these postings by accident. Very interesting Chris, I think that DCG matrices could work very well. I commend you for your work!
A few notes - please see my recent postings about paper mordanting on the Yahoo DyeTransfer group list server - the Kodak M1 mordant will work very well, and give very sharp prints with high DMAX. Fixed out paper works well, but isn't as sharp, particularly if you are making finished prints which are rewet one or more times for retouching purposes. I have been using fixed out paper (alum mordant) for test prints, and I give an additional M1 mordanting to the paper for final prints, for the best sharpness. Note - it is advisable to vigorously clean the paper surface with a very dilute photo flo solution before use to remove unwanted M1 mordant which can poison the matrix (cause the dyes to lock into the matrix,or back transfer into the matrix). This can be mostly eliminated with cleaning, but I would still recommend using a matrix clearing bath on all
While the Thorium Nitrate paper causes a Cyan hue shift to occur immediately, which can be desirable for quick evaluation of the color of the print without drying, the M1 mordant will actually give a much better correction of the Cyan dye hue than the Kodak paper, it is just that it doesn't occur until the print is dried. We have seen resulting blues, Cyans, and Greens which are much brighter than can be had on Kodak DT paper. M1 mordant - highly recommended if done correctly.
One note - the conditioner isn't really acidic, it tends to run neutral pH (7.0) to slightly acidic, pH 6.0. The idea is to have the paper more basic than the matrix, possibly causing electrostatic attraction of the dyes to the paper. If the pH of the paper is too low, no transfer would occur.
Regards - Jim Browning