First DCG, Please, Help me find the problem.

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First DCG, Please, Help me find the problem.

Post by JohnFP » Tue Oct 19, 2010 11:31 am

Excellent, excellent, excellent!!!

Crystalization is usually due to too much AmDi or KDi in the mix. Lower your concentration just a bit, maybe down to 2 grams per 100ml.
Also, I can help but notice that is seems your fall off on color is from one end to the other on both plates, so I ask, are the places where you set the plate right after veil coating perfectly level if you are laying them horizontal? If not they the gel will creap to one end as it dries. If you cant get a perfectly level (and it should be darn close to perfect) and if you do not spin after veil coating then I would suggest leaning them up against a wall or something (almost straight up and down) and let them dry vertically.

I always use this guideline for fixing. Fix until clear, no yellow left and no blue precipitate coming off the plate at all and then another 15 - 20 seconds. If it takes longer then 2 minutes then increase your exposure time, but I think you are pretty darn close on that as you stated it takes 1 minute.

Ellaborating as to what Dutchelm stated and your last statement, you do want to heat the water bath and you don't have to monitor it real close. It's suprising how close you can keep "warm" by feeling it with your fingers or hand. But keep this in the back of your mind. If you are going to warm the water bath to luke warm lets say then I would warm all alcohols to luke warm and then up the temp of the last alcohol bath a little warmer then the water and initial alcohol baths. Also, warmer baths need a slightly harder gelatin. So if you are going to warm your baths and you get a milky white hologram, then simply expose the next one a little longer and leave it in the fixer a little longer. When you get to a junction that you just go past the milky stage by doing this you will be at a very incredibly bright hologram. Welcome to the ballancing act.

Again, great work.


First DCG, Please, Help me find the problem.

Post by Kiffdino » Tue Oct 19, 2010 9:13 pm

I didn't yet have problems with too soft gelatin.
I know the bloom of my gelatin is 220.
As far as the cristilization goes. This might have been a soap-issue.
Dave told me that the anti-cristillization effect of hand washing soap in the Kdi-BAth loses its effect as time passes.
Thats exactly what i observed.
The KDI solution i mixed about a week ago.
And the plates are having more and more cristilization, up until today were the whole plate was full of cristals.

Today i made a test were i heated the washing bath to 27°C, so thats only 7°C over normal washing bath temperature.
The Plate came out quite milky.
There was a hologram, but the interesting thing was, it could almost only be seen when looking at the emulsion side.
From the opposire side it was completely milky.
The Problem might have been what John said, because the washing bath was 27°C, the proceeding ISObaths had 20°C and the final ISO100% had 60°C.
Maybe warm - cool - hot is not so good.


First DCG, Please, Help me find the problem.

Post by Dutchelm05 » Tue Oct 19, 2010 11:04 pm

220 bloom I would consider on the medium/soft side of the spectrum of gelatin.
As Joe said, if you are exceeding the springiness of the gel you will get whitening. The film needs to get harder somehow.
27C is not very warm at all and should not cause that much whitening.
Now if your have crystalization, then that is another problem.
With more AmDi(not sure about KDi) I would guess less fixing might be needed. Reason being is with more AmDi, the film should harden more via crosslinking with laser light (John what do you think?)

I guess I am getting lost in the details and not clear on what your objectives are.
Is it broadband holograms? Or just nice ones.
Maybe this is more in Dave's area but I would not think KDi is the best for broadband. I thought it was more for red shifting. Can John, Dave or Joe sanity check this? :?: I think for broadband AmDi is best. Has anyone here done BB with KDi? Perhaps you are doing some research on this in which case I apologize.
However that being said... I would consider following the methods Dave, John and Joe (Danny?? where is that guy?) have done using their formulation then branch off to some variable. There are some many variables that you can be chasing a moving target.
Just food for thought, I would hate for you to be spinning your wheels only to give up as so my DCGer do after hitting there head against the wall. :wall: :wall: :wall: :doh:

Best of luck