Tinting holograms

Simple answers are here! For Theory look in General Holography.
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rzeheb

Tinting holograms

Post by rzeheb » Sun May 09, 2010 11:46 am

Hi Bob,
The notion of tinting holograms for improved contrast (which you mentioned in reply to the previous thread) is new to me. I have color-shifted reflection holos by swelling the emulsion, but it seems that you are talking about something else entirely. Can you point me to further insite on this (maybe it was discussed in an earlier thread?)? How does one tint a hologram? I make my holos using silver halide plates and green light. TIA. Ron

Jeffrey

Tinting holograms

Post by Jeffrey » Tue May 18, 2010 8:40 pm

Long ago when emulsion/grain boundary torture caused noise, and we didn't have slick processing figured out yet, I tried dying with a solution of nigrosin, a biological stain (thank you Brad Cantos). I was supposed to darken the zones that were a problem, and did, to some extent. It darkened the total density, I think I usually used it on H1's, and did help the signal to noise ratio a bit.
Newer processes, such as CWC2 developer and Amidol bleach, first created for color holography, had the qualities of low noise and low emulsion shrinkage, and combined with finer grain emulsions such as BB, pretty much eliminated the general noise problems in silver halide. What's left is the unavoidable grain scatter - and the holographic recording of it - "grain noise" Emmett called it. That means you're recording really well.

rzeheb

Tinting holograms

Post by rzeheb » Sat May 22, 2010 8:38 pm

Hi Jeffrey. Thanks for the reply. My question about tinting was prompted by a post from BobH that was made in a different thread which I did not want to hijack. What he said was that tinting a hologram made with a red laser slightly green or conversely tinting a hologram made with a green laser slightly red was a trick used to enhance the quality of the hologram. I assume the improvement was due to improved contrast but I don't remember if that was explicitly stated. Anyway, I did a small amount of searching on the internet and learned that in the old very early days of black and white movies, the movie film was sometimes tinted, through the use of chemical dyes, to enhance certain effects. For example, tinting a scene blue was sometimes used when the scene was shot during the day but was meant to represent an evening or nightime scene. This was necessary because the film speeds were too slow to actually shoot at night. Apparently the chemical copper ferrocyanide was used to dye B&W negatives red. Since I use green laser light to make my holos, if I wanted to experiment with tinting this appears to be one agent I could try. That's as far as I got with my own research. I suspect copper ferrocyanide may be fairly toxic and dangerous to handle and I was unable to find any specifics on making the actual dye solutions and how to use them. The concept is intriguing but not really necessary so unless I can garner any further information I'll probably just let it drop. I certainly understand that top-ranked display holographers must have many proprietary tricks and techniques that they use to set their work apart and that these techniques were undoubtedly learned by hard work and lots of time and effort. I would not blame anyone for wanting to keep some of their trade secrets, secret.

BobH

Tinting holograms

Post by BobH » Sat May 22, 2010 10:13 pm

I was really referring to the early use of pyrogallol stain to increase contrast, and the staining caused by many other developers since following that lead. Also the staining Jeff mentioned above. By the way, I saw Brad Cantos a couple days ago for the first time in 25 years! He stopped to see my lasers at CLEO. Still living in San Francisco and doing well.

Tom B.

Tinting holograms

Post by Tom B. » Sat May 29, 2010 6:54 am

The most flexible and least risky tint method would be to use a colored gel (thin transparent colored plastic film) over the holo. These are available
in a bewildering variety of tints from companies such as Rosco. http://www.rosco.com/us/index.asp

rzeheb

Tinting holograms

Post by rzeheb » Sat May 29, 2010 11:20 pm

Tom, what a great, simple and eminently doable idea! Thanks.

BobH

Tinting holograms

Post by BobH » Sun May 30, 2010 2:43 am

A great example of that is the "Ancient Coins" embossed hologram by Steve Provence. It's an "open aperture" type achromatic transmission hologram that looks nicely silver. But, he also had some made on a bronze colored base that gave the coins a distinctly different look. I'll try and put up some pictures later this weekend.

Joe Farina

Tinting holograms

Post by Joe Farina » Sun May 30, 2010 11:09 am

BobH wrote:A great example of that is the "Ancient Coins" embossed hologram by Steve Provence. It's an "open aperture" type achromatic transmission hologram that looks nicely silver. But, he also had some made on a bronze colored base that gave the coins a distinctly different look. I'll try and put up some pictures later this weekend.
Of all the embossed holograms I've seen, I think those are the best. Embossed achromatic (open aperture) holograms of shallow monochromatic objects can look very nice, and it really completed the effect to have the colored bases for those coins. I can't think of any embossed holograms which turned out better.

Joe Farina

Tinting holograms

Post by Joe Farina » Sun Jun 06, 2010 3:40 pm

These are some photos of the embossed holograms Bob and I were talking about. Sorry about the poor quality of the photos, I didn't realize how difficult it was to take a good picture of an embossed hologram until now (reflections, such as from the camera, will get in the way, if the pictures are taken from the front). I must have given away the last of my "gold coins" as I couldn't find one. All in all (and in my opinion) the best embossed holograms I've ever seen.
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rzeheb

Tinting holograms

Post by rzeheb » Mon Jun 07, 2010 12:44 am

Very very nice; even knowing that the photo cannot do the hologram justice. Clarity, contrast and color are all magnificent. Thanks for posting the pix. Ron

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