DCG Dip-n-shoot, back to holography! =)

manalokos · Post by **manalokos** » Fri Jan 21, 2011 12:02 am

Hello!

I finally had some more time and motivation to try and do some Dip-n-shoot holograms,
I was getting dim results with direct Amdi mold coating, and it was a messy and dangerous job.

This time I prepared plain gelatine plates and dipped them in sensitizing solution, I was getting lousy results because
the gelatine would melt and deform the surface as the plates were set to dry, even using chilled solution.

I asked Dave for help and he told me that with my Blueish and milky results and melting, my gelatine could be too soft,
So following Dave's advice I baked a clean gel plate in the oven at 100ºC for 20 minutes and made a fresh solution with: 6g. AmDi and 100ml of distilled water and some dishwasher soap,
I cut the baked plate into 4 pieces and dipped two for 30 seconds on the chilled emulsion, while drying I noticed the gel was melting anyway
and crystals were forming. As the plates were not yellow enough I added more 3g. of Amdi, a bit more soap and a 2g. of Aluminum sulfate.
and finally I got 2 almost clean plates, not perfect but much better than the others!

Here are some results using 10 to 15 minute exposures with 30mw 532nm.Coherent 215

: Buddha

: Buddha2

: Gears

: Gears2

Best regards
Filipe

Jem · Post by **Jem** » Fri Jan 21, 2011 5:59 am

Wow Filipe, great results

Thanks for sharing your experiences.

Jem

Joe Farina · Post by **Joe Farina** » Fri Jan 21, 2011 6:45 am

Excellent, Filipe. Those are some of the better DCG holograms that I've seen posted on this forum. I especially like the photo of Buddha in your hand. It shows ambient lighting, and gives a good idea how bright the hologram is. Well done.

holomaker · Post by **holomaker** » Fri Jan 21, 2011 8:19 am

super Filipe! 15 minuets should be making you 4x5 inch holograms , what optics are you using? Try to 1/2 your exposuer and see what you get, as you say you need to get the maximum ammount of dichromate into the plates(this will also allow you to shorten your exposuers)........... looks very good, you have worked vary hard and i see its now paying off !

was this using sodium dichromate?

manalokos · Post by **manalokos** » Fri Jan 21, 2011 8:45 am

Hello

Hey Dave, thanks for all the advice, without your help I would be still looking for fringes in milky plates...
I used AmDi for the solution, I might try to put a bit more of AmDi onto the solution but I am afraid that it will crystalize,
that could be an advantage in using Sodium dichromate, as it is much more soluble in water (10xmore) it will not crystalize so easilly!

I am expanding the beam a bit more than the size of the plate so I can get a more even illumination to avoid color changing from center to edges,
but still I haven't tried shorter exposures, maybe it gets as bright as it can be with a 5 min. exposure...

Going to dip some more plates now. =)

Thank you all for the comments.
Best regards
Filipe

Dinesh · Post by **Dinesh** » Fri Jan 21, 2011 1:34 pm

Excellent job! Well done!

manalokos wrote:could be an advantage in using Sodium dichromate, as it is much more soluble in water (10xmore)

Yes, but it'll change the exposure characteristics. With dcg, it's important not to change too many of the parameters or change any one too fast.

manalokos wrote:maybe it gets as bright as it can be with a 5 min. exposure

Actually, I think, judging from your images, you are overexposing. Expanding the beam and cutting down the exposure to about 7 to 8 minutes will help.

a_k · Post by **a_k** » Sat Jan 22, 2011 3:51 pm

Great holograms, Filipe.

If such a short bath in a chilled solution causes so much trouble even with baked plates, your gelatin might indeed be very soft. How old were the plates before sensitising? Maybe using older plates would help, or using tiny amounts of dichromate in the coating mixture and preexposure to white light.

manalokos · Post by **manalokos** » Sun Jan 23, 2011 12:12 am

Hello a_k, Dinesh, Jem

Thanks!

Yes, the gelatin is quite soft (there plates were aged several weeks and still melted anyway..), but the Aluminum sulfate has worked perfectly to make it harder,
today I am exposing plates dipped some 36 hours ago and I can see they are getting dimmer and more narrowband,
I don't know if this progression is normal, or if it should take more time, I suspect that the aluminum sulfate makes
the plates age more quickly, but it is not an issue as I can make fresh plates and shoot them after dry dry up with no problems,
all I need is some blank gel plates ready to dip! I could try and use the NaDi but I already have some flasks with bad solutions (and I am out of flasks), and
don't want to waste all my stock of metabisulfite neutralizing the bad solutions, they'll stay in the flasks until I find a way to get rid of them...

I noticed that if the first developing is not perfect I can reprocess the plates, but they get up to the green and (blue and dim) if I reprocess them 2 times.
If I have broadband results reprocessing is more forgiving and can even make the hologram look whiter...

Today is a very cold day, would room temperature influence the outcome of the exposures? If yes, in what way?

Best regards
Filipe