Holographyforum.org / holowiki.org

Johnfp · Post by **Johnfp** » Thu Oct 13, 2011 9:06 am

Can someone explain to me how to use TEA to get the final Red reflection hologram to come out yellow?

How much to use, how to dilute it, when to soak the plate, when to wash it out...etc.

I want to get some but I dont know whether to buy 100ml or a quart.

Joe Farina · Post by **Joe Farina** » Thu Oct 13, 2011 9:31 am

Buy a quart

TEA is cheap, you will need to experiment just a little to get the yellow you want.

Ed Wesly · Post by **Ed Wesly** » Thu Oct 13, 2011 9:58 am

Here is something I wrote a long time ago. http://nlutie.com/ewesly/TEA.html

I did do the experiment described, last time I looked at it still looked the same, but I need to photograph it digitally and post it.

As usual, the exercise is up to the individual student to calibrate their technique. On this forum, Bobh is undoubtedly the master expert on this topic. Consistency in your squeegeeing (one of the few times I squeegee emulsions, you really have to in order to get the thick stuff out) or one step further spin drying is key to the operation.

What concentration for yellow? Trial and error is the name of the game here, because of emulsion hardness, processing scheme, etc. But it would be low, like under 5%.

But masters of the technique like John Kaufmann would make yellow by double exposing a TEA'ed green with an un-TEA'ed red. Even more hard work!

Good luck in your ventures!

Johnfp · Post by **Johnfp** » Thu Oct 13, 2011 11:17 am

From Ed's link

A holographic plate soaked in a 10% solution of TEA in water will swell up three to ten times its original thickness while wet, but when the water dries out of the gelatinous sponge, the ten per cent of oily TEA is left behind, now swelling the emulsion to about 10% thicker than at first.

So I totally get it. If I am using 633nm and want to replay in 580nm, then need to swell by 53nm or about 8.5%.

Thank you Ed. The rest will be trial and dial but at least I have an understanding and a starting point.

Yes it is cheap Joe, I will get a quart. 100ml wont last long. Thank you.

Jem · Post by **Jem** » Thu Oct 13, 2011 2:21 pm

To get yellow replay couldn't you just control that with the type of developer/ bleach combination rather than using TEA.

I'm using Pyrochrome developer and Acid Dichromate bleach for my H2 image plane holograms and they're coming out a nice golden colour.

Johnfp · Post by **Johnfp** » Thu Oct 13, 2011 6:34 pm

Not sure Jem, I have not make silve holograms in quite a while.

But if what you say is correct then I got some Pyro laying around. I could try it. I remember using it for H1's to keep the replay the same with AmDi bleach.

Jem · Post by **Jem** » Fri Oct 14, 2011 4:46 am

John, i'm no expert by any means, but have a look at this picture I posted in the Gallery recently...

http://holoforum.org/forum/viewtopic.php?f=10&t=304

This was made using Agfa film and processed with Pyro 10g litre (as part one) and Sodium Carbonate 60g litre( as part two), I always use distilled water for mixing. Mix the two parts just before developing. I then used Acid Dichromate bleach.

I've made quite a few holograms since this one and all have come out this nice golden colour. Although, I have noticed that if I increase exposure the hologram shifts towards green.

Hope this helps

Jem

Johnfp · Post by **Johnfp** » Fri Oct 14, 2011 5:52 am

Thanks for sharing, Jem.

Sounds like the Agfa may be a softer emulsion, combined with the lower exposure. I still may give it a try with PFS01 after a TEA or water soak to soften it.

Tom B. · Post by **Tom B.** » Sat Oct 15, 2011 5:06 am

I bought 100ml years ago and have used about 40 ml. TEA solutions are re-usable for quite a while. My major breakthrough with TEA was discovering that after drying a TEA-soaked plate, there was a slight oily film residue left on the glass side which scattered light When this was wiped off with a damp paper towel before exposure, my black level and apparent contrast improved dramatically - any even small unwanted reflections or scattering in your setup that are visible from the plate degrade the image contrast. If you shift your eye to the plate plane, you will be surprised at how many unsuspected reflective things are bouncing unwanted light at you, competing with the delicate thing you want.

John Sonley · Post by **John Sonley** » Sun Oct 16, 2011 9:19 am

Tom B. wrote:I bought 100ml years ago and have used about 40 ml. TEA solutions are re-usable for quite a while.

Tom - I find that the diluted TEA I have used (5% by volume) starts to go 'off' with floating white bits in suspension if stored at room tenperatures for a month or so. It could be that I make the solution up using 'distilled' water from my lab. de-humidifier and it's quite likely that there will be some bacteria in the water, upon which the amine will feed