PDA

View Full Version : Red Sensitive Dye ?



Pages : 1 [2] 3 4 5

VesaL
08-22-2013, 02:25 AM
Falotico, thank you for the info. Im having methyl violet in powder form, but i believe i can dilute it some into distilled water with correct 1:20 000 ratio, and mix this into 50 % alcohol solution. I am waiting for a set of glass plates that are being custom cut for appropriate size, should be ready by tomorrow. After this I can start coating them with gelatin / emulsion layer and start experimenting with Red sensitizing.

The Ice bath probablty was used as to reduce the vaporization of the alcohol. This gets interesting. I will post some results but this will take some time.

-Vesa

rwhb12
08-22-2013, 07:52 AM
I have had some correspondence with eBay member scuddl_lu6725tbtc@members.ebay.co.uk aka Alan Meredith-Jones of magancol Ltd in the uk who supplies many dyes. May be worth a try.

russ

Hexavalent
08-22-2013, 10:00 AM
What in the heck kind of ANYTHING on this earth could cost $16,800 an ounce? That doesn't make sense. What good could it have possibly have been even to a company like Kodak was in film manufacture at a crazy price like that. Surely there is another reasonable alternative to making film panchro.

$16 k / ounce is not an unreal price for many fine chemicals, e.g. Aflatoxin = a several $100,000 per ounce.

The 'high prices' quoted by Sand's Corp. etc., are usually for small amount - the wholesale price for large purchasers is likely a small fraction of the the price given to the average Joe.

Tom1956
08-22-2013, 11:20 AM
I just googled this about the methyl violet and WW Grainger popped up as a supplier, as per link. This could be interesting to continue reading this thread,
http://www.grainger.com/Grainger/wwg/search.shtml?gclid=CODQto25kbkCFctr7AodhjYAVA&searchQuery=Methyl%20Violet&op=search&Ntt=Methyl%20Violet&N=0&GlobalSearch=true&sst=subset&cm_mmc=PPC:%20Google%20Main%204-_-Lab%20Supplies%3ELab%20Chemicals-_-Analytical%20Reagents%3EMethyl%20Violet%3EBroad-_-Methyl%20Violet&ef_id=zItP9kMfkiYAAF69:20130822161322:s

falotico
08-22-2013, 03:35 PM
Methyl violet will probably sensitize close to the same manner as ethyl violet. From the absorbence spectrum which I have seen published, ethyl violet sensitizes an emulsion to orange/red light rays as long as 6500 nm and methyl violet sensitizes to about 6400 nm. Both dyes improve red sensitizing when combined with a silver nitrate wash. I don't know why Yoshida lowered the temperature of his dye bath with ice, though I suspect that the lower temperature suppressed the index of absorbence of the dye and allowed a longer time in the dye bath which would cause smaller grains to be dyed.

Autochromes used ethyl violet as a sensitizing dye for orange/red light. If you notice that Autochromes do not record rich reds very well; most of the red tones lean to the pink/magenta. I suspect that this will be even more of a problem with methyl violet.

Tom1956
08-22-2013, 03:47 PM
The reason I'm following this thread is a hairbrain idea of wondering if you could simply soak sheets of green X-Ray film in a solution of this violet stuff and raise the sensitivity closer into the red end of the spectrum. If anybody wants to comment on this knucklehead idea, I'll read it gratefully.

falotico
08-22-2013, 04:44 PM
Wow, X-ray film! My recollection is that X-ray film contains chemicals which will fluoresce when irradiated with x-rays. The x-ray exposure causes fluorescence and the silver halide grains are sensitive to the visible light which is produced in this manner. I hazard a guess that the visible light is green/blue in color, so the x-ray film is probably sensitized to green/blue. Sensitizing dyes tend to be ionically attached to the silver halide grains so they should be removed in order to make room for the red sensitizing dye. You might mix the red dye sensitizing solution with ammonia which might dissolve some of the built-in dyes; it will certainly dissolve the small percentage of silver chloride grains since silver chloride is soluble in ammonia. Also ammonia might soften the gelatin which has probably been hardened--a softer gelatin will encourage the up take of the red sensitizing dye. Hydrogen peroxide will also soften hardened gelatin. All this is fairly convenient chemistry.

Tom1956
08-22-2013, 05:06 PM
Well I figured it couldn't be that easy. It PE even saw read that hairbrained post of mine, he's probably rolling his eyes and possibly rolling on the floor laughing. I'll exit the thread and let all it to return to the better minds like the OP had sought.

dwross
08-28-2013, 03:56 PM
Did anyone see and note holmburger's suggestion? Post #12. It was very sound. Pinacyanol chloride, together with erythrosin b, makes a perfect (and I mean that pretty much literally) panchromatic emulsion.

d

kb3lms
08-28-2013, 06:26 PM
My recollection is that X-ray film contains chemicals which will fluoresce when irradiated with x-rays.

Not exactly. The film is either just blue sensitive or orthochromatic. When used it is sandwiched in a cassette (flat film holder that opens like a book) between two phosphor coated plastic sheets, called screens, that fluoresce when struck by x-rays. In many ways it is a fairly conventional film although the spectral response is tuned to the spectral emission of the screens for maximum sensitivity. It is also coated on both sides, no anti halation and often on a blue colored base. Whether the dye trick would work or not I do not know but there is nothing really different about the film. Large format photographers use it sometimes because it is cheaper as it is still made in considerable quantity - compared to sheet films.

Photo Engineer
08-28-2013, 06:50 PM
Guys, X-Ray film is placed in contact with a screen the fluoresces when struck by X-Rays. Nuclear emulsions, sensitive to radiation, contain a substance to enhance their sensitivity to specific radiation. See Mees or Mees and James for this.

Chlorophyll is used by Mark Osterman at GEH. He uses Ivy, and extracts the dye getting a greenish solution. It does not keep its properties long.

Chris' list should serve us well, as should his suggestion.

I have not been able to get any information from my contacts, but some of the chemicals Chris suggests are available commercially.

There, that should answer most questions.

PE

Hexavalent
08-28-2013, 06:53 PM
Pinacyanol has been discussed at great length over the past few years. AFAIK, the variability in aggregation, and a tendency to floculate can make it a bit tricky for controllable and repeatable results within the "home lab".

Tom1956
08-28-2013, 08:14 PM
Guys, X-Ray film is placed in contact with a screen the fluoresces when struck by X-Rays. Nuclear emulsions, sensitive to radiation, contain a substance to enhance their sensitivity to specific radiation. See Mees or Mees and James for this.

Chlorophyll is used by Mark Osterman at GEH. He uses Ivy, and extracts the dye getting a greenish solution. It does not keep its properties long.

Chris' list should serve us well, as should his suggestion.

I have not been able to get any information from my contacts, but some of the chemicals Chris suggests are available commercially.

There, that should answer most questions.

PE

Did it answer MY question too, because if it did, I'm sure I'm not versed enough to notice.

Photo Engineer
08-28-2013, 10:26 PM
IDK. Restate the question!

PE

Tom1956
08-28-2013, 10:33 PM
Post 26 and 28:
08-22-13 04:47 PM #26 (http://www.apug.org/forums/viewpost.php?p=1539129)
Tom1956 (http://www.apug.org/forums/members/tom1956/)
http://www.apug.org/forums/images/apug4/statusicon/user-online.png
http://www.apug.org/forums/images/memberpixel.gif Join DateMay 2013LocationUSShooterLarge FormatPosts626


The reason I'm following this thread is a hairbrain idea of wondering if you could simply soak sheets of green X-Ray film in a solution of this violet stuff and raise the sensitivity closer into the red end of the spectrum. If anybody wants to comment on this knucklehead idea, I'll read it gratefully.

dwross
08-29-2013, 08:56 AM
Pinacyanol has been discussed at great length over the past few years. AFAIK, the variability in aggregation, and a tendency to floculate can make it a bit tricky for controllable and repeatable results within the "home lab".

I think I see the crux of the problem for this forum. (At least I see it as a problem.) "...has been discussed at great length..." Yes, much discussion of everything under the sun. Much less doing. And, far too many conclusions drawn from the discussions -- with little empirical evidence to back up said conclusions. I'm a retired scientist. I'm not much given by nature or training to act that way. I've got a number of lovely handmade panchromatic film negatives and glass dry plates on my light table.

d

Photo Engineer
08-29-2013, 10:34 AM
Post 26 and 28:
08-22-13 04:47 PM #26 (http://www.apug.org/forums/viewpost.php?p=1539129)
Tom1956 (http://www.apug.org/forums/members/tom1956/)
http://www.apug.org/forums/images/apug4/statusicon/user-online.png
http://www.apug.org/forums/images/memberpixel.gif Join DateMay 2013LocationUSShooterLarge FormatPosts626


The reason I'm following this thread is a hairbrain idea of wondering if you could simply soak sheets of green X-Ray film in a solution of this violet stuff and raise the sensitivity closer into the red end of the spectrum. If anybody wants to comment on this knucklehead idea, I'll read it gratefully.

Thanks.

Yes, it can probably be done but most sensitizing dyes are also desensitizers and so getting the correct amount is difficult. And proving it works is another matter.

PE

Photo Engineer
08-29-2013, 10:36 AM
I think I see the crux of the problem for this forum. (At least I see it as a problem.) "...has been discussed at great length..." Yes, much discussion of everything under the sun. Much less doing. And, far too many conclusions drawn from the discussions -- with little empirical evidence to back up said conclusions. I'm a retired scientist. I'm not much given by nature or training to act that way. I've got a number of lovely handmade panchromatic film negatives and glass dry plates on my light table.

d

Denise, I agree. However, I must ask if you have wedge spectrograms of your pan emulsions showing good red sensitivity? This would be hard scientific evidence that it works. If you don't, I would be happy to expose a few of your plates for you and return them to you for processing, as I have a Spectro Sensitometer. That is the ultimate proof.

PE

dwross
08-29-2013, 11:00 AM
:) Thank you. That's a generous offer. I know how valuable your time is.

Actually, I disagree with that approach for us at this time and place in the history of our craft. I think it is a fundamental mistake to consider our efforts a de facto competition with standards based on the latest modern materials that come from a Kodak factory. That's the exact rabbit hole the discussions here so often travel down.

Today, my hat says 'artist'. I believe good art more often comes from good practices more than from dumb luck, but it is still art. An artist makes the materials his or her own according to personal vision. In other words, the "proof" is in the product (i.e. the art), not a number on a machine. Arbitrary, spurious precision may be seductive, but mostly it's an excuse to procrastinate making good art.

d

Photo Engineer
08-29-2013, 12:04 PM
Denise, I was going by your previous post suggesting that we all get more evidence of our conclusions. This test would compare nothing to nothing in the sense that your plates would be for you alone (even I would not see the results!) and thus you would have that concrete evidence of pan sensitization rather than a guesstimate.

Any time, I am available for helping you just as I spend time with others here either designing processing solutions or making emulsions.

Ron