yesterday's DCG

Joe Farina · Post by **Joe Farina** » Mon Dec 31, 2007 6:28 pm

These are two I did yesterday on month-old plates from the fridge. I did a quickie sculpture and attached it to a plaster base. The object in the background is a box of Knox gelatin. The one on the right is more broadband (even though it looks greener in the photo for some reason) and a bit brighter, but much noisier. I don't know why the photo turned out blurry, it looks sharper than this.

Dutchelm05 · Post by **Dutchelm05** » Mon Dec 31, 2007 7:46 pm

Joe Farina wrote:box of Knox gelatin.

Really impressive Joe, so clear and greath depth. How far back is that box?
I love the long shadow effect
So the box of gelatin was just sitting there?
I always was under the impression that objects had to be pretty ridge.
Happy New Year to you
Regards,
Tony

Joe Farina · Post by **Joe Farina** » Mon Dec 31, 2007 8:03 pm

Thanks Tony. The box was about four inches back, resting on the table along with the plaster block. The exposure was only 20 seconds. I've found that when an exposure is that short, almost anything is stable enough (at least to get some kind of image). But when it goes up to a minute or two, it seems like almost nothing is stable enough, and I need to use stuff like metal, plaster, etc.

MichaelH · Post by **MichaelH** » Mon Dec 31, 2007 8:35 pm

Very nice Joe. What formulation and coating method did you use? I'm definitely jealous of those. Most of mine so far have been quite a bit dimmer.

Joe Farina · Post by **Joe Farina** » Mon Dec 31, 2007 8:42 pm

Thanks Michael. It was 3-30-200 coated with a bar.

Dutchelm05 · Post by **Dutchelm05** » Tue Jan 01, 2008 2:22 am

Hey Joe,
How about IPA bath temp? Didn't you mention that you use warm water and cooler IPA?

What do you think is the main reason you made a pretty good quantum leap?

Glad to see such awesome results. Well better get back to the the party

Couldn't resist one last posting for 2007

Tony

Joe Farina · Post by **Joe Farina** » Tue Jan 01, 2008 12:46 pm

Hey Tony. The alcohols were at 17C, and the water soak was at 23C. As of now, I plan to vary the water temperature to get different results. I see that it has a pretty huge effect on the outcome. My gelatin concentration is high (13%), the dichromate concentration is low (1%), and I'm lucky enough to have a 458nm laser, so these might be factors to consider.

JohnFP · Post by **JohnFP** » Wed Jan 02, 2008 12:57 pm

Great job Joe!!!

Danny Bee · Post by **Danny Bee** » Wed Jan 23, 2008 12:22 am

hi Joe great job!

we have the same laser 457nm ... i was trying your mix 3-30-200 .... so its 1.5% chrome right?
what was the method of hardening? light or fixer? also what was the thickness 10 microns 20 microns?

Joe Farina · Post by **Joe Farina** » Thu Jan 24, 2008 4:18 pm

Thanks Danny. The 3-30-200 was Rallison's suggestion for "red" holograms using a blue laser. I figured it would be better to have expansion in the final DCG layer, rather than shrinkage, because at 457nm, if there was shrinkage, it would probably be dim blue, or maybe vanish into the UV. Yes, 1.5% ammonium dichromate is about right (3 divided by 233 would be 1.3 %). As for hardening, I usually don't harden at all, because I use Knox gelatin and and all of my baths are cool, except for the water soak. I try to monitor the temperature of this water soak closely, a typical temperature would be around 23C, but it depends on the hardness of the layer. If I need extra hardening for some reason, I use a 100W frosted light bulb in front of the emulsion, for varying time periods. I didn't measure the thickness of the coating, but I used a #24 bar.