Hmmm... Just made a hologram using a BB520 plate. I was trying a slightly different SBR (Denisyuk style) setup. I did the usual pre-soak in TEA/Photoflo, followed by exposure and developing using Pyro dev and EDTA bleach.
As soon as I put the plate into the bleach I could see the hologram appearing and it looked really bright. I rinsed in water, squeegeed and let the plate dry. The hologram disappeared!, where did it go?, the image was really good when the plate was wet.
Any suggestions as to what went wrong? Simple answers please as I still very much consider myself new at this game
Your emulsion was so wet or swollen when you exposed it that when it dried the fringes shrink and now the hologram wants to replay in the UV. No I doube you can see it under a black light, it would have to fluorese. If you soak it in some post swelling agent (the ones used to shift a green hologram to gold) then redry you may be able to save it.
@ Kaveh... Wow, what a super little 'film' and a great easy to understand explanation.
@John... Thanks for your explanation, coupled with the above it is now clear. I guess I didn't allow enough time for the plate to dry. I did try re-wetting the plate and it is quite an nice hologram... when it's wet . I'll try your suggestion of 'post swelling' to see if I can save it... Then again, i've never done 'post' swelling. Can you use TEA for this? I'd love to shift my greens to golds
The silver experts can tell you what chemical to use, but I had sucess shifting about 75nm with regular old sugar. Just mix up 2 grams of sugar to every 100ml and soak the plate, squeegy, and dry as normal. Some of the sugar stays in the hologram causing a red shift. Not sure if it would be enough for you. And I am not suer what the "chemical" post swelling does as far as how far it would shift. I did find in my testing that adding more and more sugar never took me past a certaing shift limit. Not sure if it was the sugar or if there is a maximum amount of shift the fringes would allow, probably the latter.
Jem wrote: Then again, i've never done 'post' swelling. Can you use TEA for this?
Legend has it that TEA is no good for this because it causes printout - gradual darkening of the plate due to self development under light. This makes sense since TEA is a sensitizer. As an alternative to table sugar, some prefer to use sugars that are hopefully less attractive to bacteria such as sorbitol and xylitol - available at some health food stores. Whether they really make a difference in hologram longevity is unknown to me.
As an alternative to table sugar (with which I too have had some success), you can probably have some fun experimenting with citric acid.
When I first started making reflection holograms on VRP-M (@532nm), I kept getting final images that were rather blue. I initially chalked this up to humidity in my area, but later found out that I was getting said blue-shift from my potassium dichromate bleach - it was shrinking the emulsion after development. After reading that sorbitol is in essence a sugar, I attempted some post-swelling with a mixture of ~ 1 teaspoon table sugar/150mL distilled water plus a touch of wetting agent as my final bath. I gave my VRP-M plates a one minute soak in this bath then squeegeed and dried. This much sugar pushed my images into the green band again. They took a long time to dry following a post-swell. Often the image would appear to have dried to a red color, only to continue drying through orange and into yellow then finally green... Twice the sugar in the concentration would result in an infa-red image that would eventually dry into a red holo.
So.... Sugar swells emulsion. Quite nicely, really. And cheaply. And obtainably.
Citric Acid works better. It takes longer to soak into the film (~half hour), and longer to dry, but IMHO dries to a more stable final color that is less likely to shift due to changes in humidity or other environmental factors. So that's nice. It's also purported to help arrest print-out. Don't quote me on that one though.
About your viewable-only-when-wet hologram... I had the same thing happen one time with a transmission 'gram that I tried to index emulsion-side-to-glass with water when shooting. The fringes wound up being recorded in swollen emulsion and therefore their geometry was based on the thickness of the plumped emulsion. Apparently upon drying the fringes laid down flatter in the thinner emulsion and wouldn't replay the image at the expected angle. But Kaveh's presentation helped straighten me out (it was a beauty, wasn't it? Thank you again, Kaveh!)
So... Yessir. If you are interested in experimenting with some color-shifting in the future, table sugar is definitely a great place to start. When you bump up against the edge of the sugar envelope, citric acid is a great alternative to try.
My holograms continue to get better all the time (i'm still using ready made BB plates from Colorholographic in the UK), but the green colour (from my 532-200) tends to get a bit boring after a while. I'm now completely inspired and am eager to give the post swelling a try. If I can get them to shift towards yellow/gold that would be really cool.
So I was following this thread and I thought, hey, I use VRP-M plates, I make H2s that also turn blue/green after chromate bleach, why not try this citric acid idea? So when I got home from work today, I wipped up a batch of DI water with a spoonful of citric acid and a few drops of photoflo (I didn't measure anything very carefully). I soaked a plate for about 45 minutes, squeeged and dried with a hot air gun. Worked like a charm! My plates color shifted from blue/green to green/yellow. It seemed brighter too, which may be because the human eye is most sensitive to yellow/green? Anyway, as they say in my part of the world, "cool beans" and thanks. I really love learning, trying and sometimes even succeeding at new things. :dance:
. I'll try your suggestion of 'post swelling' to see if I can save it... Then again, i've never done 'post' swelling. Can you use TEA for this? I'd love to shift my greens to golds 
:dance: