pre-fix wash?
Posted: Mon May 25, 2020 9:53 pm
See thread "DCG processing, comparing apples with oranges." Paraphrasing
Jeff Blyth and JohnFP, The important bit is that CR+3 is a hardener.
I was using K metabisulfite to kill off the CR+6, and reusing the solution,
since it was still working. However it was also becoming a more and more
concentrated hardener. So my holograms kept getting dimmer, and conflating
what I thought I was varying.
So the new hypothesis is wash out the CR+6 in distilled water. Which will
allegedly not wash out CR+5 and CR+3 in the exposed areas. Then fix with
K metabisulfite, which will turn all the CR+5 into CR+3, and cross-link, like
a hyper-active dark reaction. But it will not touch the unexposed areas
because the CR+6 which was there got washed out.
Does this seem plausable?
This hologram is:
18% 250 bloom gelatin, coated with a meyer bar
dried a week ago
sensitized in 5% K dichromate for 1 minute
quickly rinsed off in 1/2 % K dichromate, to avoid crystallization
dried overnight (about 12 hours)
exposed for 200 seconds at 100 uW/cm^2 457 nm
1 minute wash in distilled water
1 minute in 1 percent K metabisulfite
5 minutes in swelling bath at 24C
2 minutes in 70% at 24C
2 minutes in 91% at about 28C
2 minutes in 99% at about 28C
dried with a heat gun
The result was milky extremely wide-band, possibly widest I've ever made, with
very cool water. My previous attempts which looked like that were more like 34C.
Though also with 1/10 the dichromate.
I'm doing extremely long baths in the IPA to avoid chirping by giving it lots
of time to diffuse through the gelatin. It isn't working or I'm missing
something else, my results are very wide-band. What is the actual drying
mechanism? I thought it was diffusion/osmosis where the high concentration
water is encouraged to go to the low concentration water in the IPA.
The dichromate concentration is probably too high, others seem to use more like
0.5 percent, but my previous attempts were very dim, making me want to increase
it. (but they may have been dim because they were over hardened...)
The plate absorbed about 75% of the light (reducing 108 uJ/cm^2 to 27 uJ/cm^2),
measured with a power meter, plate held about perpendicular to the light. That
there is am image at all seems to support it being not completely wrong.
Jeff Blyth and JohnFP, The important bit is that CR+3 is a hardener.
I was using K metabisulfite to kill off the CR+6, and reusing the solution,
since it was still working. However it was also becoming a more and more
concentrated hardener. So my holograms kept getting dimmer, and conflating
what I thought I was varying.
So the new hypothesis is wash out the CR+6 in distilled water. Which will
allegedly not wash out CR+5 and CR+3 in the exposed areas. Then fix with
K metabisulfite, which will turn all the CR+5 into CR+3, and cross-link, like
a hyper-active dark reaction. But it will not touch the unexposed areas
because the CR+6 which was there got washed out.
Does this seem plausable?
This hologram is:
18% 250 bloom gelatin, coated with a meyer bar
dried a week ago
sensitized in 5% K dichromate for 1 minute
quickly rinsed off in 1/2 % K dichromate, to avoid crystallization
dried overnight (about 12 hours)
exposed for 200 seconds at 100 uW/cm^2 457 nm
1 minute wash in distilled water
1 minute in 1 percent K metabisulfite
5 minutes in swelling bath at 24C
2 minutes in 70% at 24C
2 minutes in 91% at about 28C
2 minutes in 99% at about 28C
dried with a heat gun
The result was milky extremely wide-band, possibly widest I've ever made, with
very cool water. My previous attempts which looked like that were more like 34C.
Though also with 1/10 the dichromate.
I'm doing extremely long baths in the IPA to avoid chirping by giving it lots
of time to diffuse through the gelatin. It isn't working or I'm missing
something else, my results are very wide-band. What is the actual drying
mechanism? I thought it was diffusion/osmosis where the high concentration
water is encouraged to go to the low concentration water in the IPA.
The dichromate concentration is probably too high, others seem to use more like
0.5 percent, but my previous attempts were very dim, making me want to increase
it. (but they may have been dim because they were over hardened...)
The plate absorbed about 75% of the light (reducing 108 uJ/cm^2 to 27 uJ/cm^2),
measured with a power meter, plate held about perpendicular to the light. That
there is am image at all seems to support it being not completely wrong.