what happened here?

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d paul

what happened here?

Post by d paul »

I was wondering if anybody out there could tell me what happened with this dcg holoImage
Iused a regular gelatin/glycerin plate,sensitzed with 6% KDi solution for 3.5 min then dryed. It was exposed for 15 min with 20mw @532, waved it in the spread beam,washed it for 3 min in tap water,soaked it for 1 min in 25degree c water then 3min of 70% and 99% IPA. Ifigured it was the high temperature for the soak, but the plate didn't get milky, and it is really bright
thanks in advance
rob
dave battin

what happened here?

Post by dave battin »

rob can you show another angle? or maybe a motion picture? is it possible the glass is not flat?it kind of looks like thickness variation in the film. its as hard to say ,as it is to photograph!
JohnFP

what happened here?

Post by JohnFP »

I have a few questions also.
What were the objects? (photo would be nice)
How did you coat?
Did you coat plain gelatin and glycerine and then sensitize after gelatin was dry?
How did you final dry? For how long?
What was formula of gelatin, gycerine and water?

Off hand it looks like a combination of movement (the objects near bottom where just edge shows), uneven coating or too much glycerine (greenies and bluees) and incomplete drying (orange areas and areas still black at edge of bright areas). Also, possibly a very thick emulsion.

Temps at 25C are not too hot.
d paul

what happened here?

Post by d paul »

okay
First here are pictures at different angles plus a shot of the objects
Image
Image
Image
Image
Now for the answers:
I used a mix of 50ml DIwater
0.6g glycerine
6g Knox gelatine
This was mold coated on a piece of plate glass with tape running across to let me put a 4x5 plate on the puddle, with the tape looking like railroad tracks, and the plates forming the crossties. I used 2.5-3 ml per plate, and once they set I peeled them up, and let them dry under a fan. I sensitsed them with 6%KDi about an hour before use,drying again with a fan.
After processing, I air dryed it, then put it into a toaster oven with stone tiles loaded in at 100-105 degree c for 40 min or so. I put the tiles in to steady the heating rate of the oven-once I found the spot on the dial for 100 c , I painted it on so I'd keep it there.
Only two plates came out like this out of a run of ten,so it probally was something off with just those two,as the rest came out really well. I was having trouble with the water bath temp swinging around, but I now have an immersible aquarium heater that holds it steadier(Ineed a 100w job to make rock steady)

Thanks guys
rob
JohnFP

what happened here?

Post by JohnFP »

Dave, what do you think? From the last image of the hologram it looks like a thinkness issue, no?
jean

what happened here?

Post by jean »

Or borders are underexposed ?
JohnFP

what happened here?

Post by JohnFP »

Yes, It definitely looks like the two sides are underexposed, too thick or incompletely dried.
d paul

what happened here?

Post by d paul »

Thanks for the diagnosis guys. Now I know what happened, I can try to correct it. Two duds out of ten or so isn't bad though
rob
Hans

what happened here?

Post by Hans »

When you expose MBDCG, there is always a sharp transition in result at a certain exposure level. For example, 50mJ gives a yellow broad-band image, 55mJ gives a green image. At even higher exposure energies, there is another colour transition (usually a dull green), and at even higher energies than that towards blue. Since the colouration in your plate happens in the middle, I think the same is happening there.

I found that it can be fixed in MBDCG by a longer uniform post exposure (waving the plate in the beam longer).

I don't know however if this all applies to MBDCG as well.
d paul

what happened here?

Post by d paul »

Thanks Hans, I had no idea that you could get color transitions thru exposure levels. It would make sense because only two plates ended up like that, and I may have adjusted something and changed the beam pattern when I shot them. You should see the ones that came out better .
rob
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