Aurora in the darkroom / stop flash

[tony lockerbie]

What bewilders me is the concept of a College being a drug free zone! I have been reading a very old book on photographing the invisible, and clearly what you have here is ectoplasm.

Tony

 

[keithwms]

Was it a "Voila!" or a "LOOK OUT!" type of light?

I'd say it's more of an Eh? and scratch your head type of light. It's subtle, and not accompanied by heat.... or sound. I thought that ectoplasms would make a kind of "woo-oo-ooo" sound.

 

[Kirk Keyes]

Ectoplasm - who ya gonna call? Ghostbusters!

 

[Síle]

A green light you say..
That's very obviously a form of electromagnetic radiation or light emission of frequencies.
Which is produced by sub-atomic particle interactions, such as electron-positron annihilation or radioactive decay.
And if you're not careful, you'll end up just like this..

 

[Leon]

I blame Chernobyl

 

[railwayman3]

It's well documented that there are various chemical reactions which actually do generate light....occurs in nature with glow-worms and luminescent fungi ("bioluminscence").
Guess you've stumbled upon a similar example.
See: http://en.wikipedia.org/wiki/Chemiluminescence
(Bit technical, but you get the idea!)

 

[N O Mennescio]

It's probably just quantum

 

[Removed Account]

I blame the liberal media! They're obviously trying to ignite some chemical scare, and we all know hippies like the colour green.

 

[Lee L]

What bewilders me is the concept of a College being a drug free zone!

Could be Liberty University in Lynchburg... different opiate according to Marx.

Lee

 

[panastasia]

I blame the liberal media! They're obviously trying to ignite some chemical scare, and we all know hippies like the colour green.

I thought it was red, orange and purple (Strawberry Fields, Orange Sunshine and Purple Ozly)

 

[keithwms]

lol

Lee, I am not at Liberty!

I like the hulk theory though, I did notice some new muscles sprouting this morning... Don't make me angry, you won't like me when I'm angry.

Railwayman, you went and spoiled the mystery! Actually I guess I already spoiled it when I mentioned chemiluminescence. Indeed an excited state intermediate is forming in the developer, and when that alkali hits the stop (which is big pH swing), *flash* the excited state is quenched. It's not too suprising that a ring-based compound, such as found in the pyrocatechol-based developers, acts this way. What is surprising to me is that this can be seen so readily and without a more oxidative quench treatment such as from peroxide or such. Anyway there has to be a reason why it's called pyro, right?!

Anyway, I googled pyrocatechol + chemiluminescence and the very first hit looks like I won't be scoring a Nobel for this one...

http://cat.inist.fr/?aModele=afficheN&cpsidt=15395837

This isn't the first time The Google stole my thunder.

 

[Lee L]

lol

Lee, I am not at Liberty!

Neither are the all non-tenured teaching staff at Liberty University. The name Liberty University is an oxymoron.

I figured you weren't working there... if I had thought you were, I probably wouldn't have made my little joke.

However, this does eliminate any number of "creationist style" explanations I could come up with for the pyro+stop luminescence, so I'm throwing away points here.

Lee

 

[keithwms]

Here's an excerpt of an article on the chemiluminescence of pyrogallol as it is oxidized....

Mr. Evmiridis is nice enough to furnish us with an explanation in his introduction:

An exothermic reaction may also release energy in other
forms of energy apart from heat. Reactions that release energy
greater than 41 kcal per mole can give CL-emission. Oxidation
reactions are usually accompanied by large energy release.
The wavelength of CL-emission is calculated from the equation
E = hc/λ, (1)

where h = Planck constant, c = the velocity of light, and λ =
the wavelength of the emitted light.

Now back to practical matters... I suppose that it might be possible to get a fog front on your film from this chemiluminescence. I'll see if I can make that happen next time I am doing some tray dev'ing with pyro. My guess is that the trailing edge of the film, as it is inserted into the stop, might accumulate a bit of fog. Unlikely to be an issue though, if one doesn't pause while inserting it, or if excess developer is shaken away first, or if the developed film goes into a water bath.

P.S. Lee, I don't think one can deny that these films were intelligently designed....

 

[railwayman3]

lol

Railwayman, you went and spoiled the mystery!

Sorry, guess I got over-excited that something which I studied in school science umpty-tumpty-years-ago had, after all this time, actually provided an answer to a real question!

 

[keithwms]

That's alright, Ole and I spoiled the mystery amongst ourselves a few days ago in PM Ole mentioned polymerization giving the brownish colour of the developer as it ages, which is an aspect I hadn't thought of.

 

[Kirk Keyes]

SO which developer should I use to get the best chemiluminesence - PMK, WD2D+, or Pyrocat??? ;^)

 

[keithwms]

Probably all the pyros will do this but I have only mucked with wd2d+ so I can't say for sure.

Let me add a few details that may or may not affect your observations.

(1) When mixing up my parts A and B, I took the admonition to use steam distilled water seriously. I did not, however, leave the water in an open container to "allow time for excess oxygen to leave the water." I figure that if it were that serious an issue then one might vacuum cap the part A and part B or at least bubble N2 through it before sealing. Maybe I'll do that next time... store my part A and B in wine bottles.

(2) I tried to generate the CL with freshly mixed part A+B and didn't see it nearly as strongly, so I think the developer needs to "age" and you're probably best off pouring some stop bath into the dev bath after you've finished a batch of processing. This is consistent with Ole's comments about polymerization.

(3) I also thought I might intensify the CL by mixing fresh part A+B + stop... in fact I saw little if any CL. So again there appears to be an issue of letting the developer crosslink. I suppose silver may act as a catalyst for the polymerization.

(4) I do my wd2d+ development at room temp or 23.5 C.

(5) Finally, the strongest observation of CL was when I transferred the film directly into the ilfostop, with no water bath in between.

Enjoy the pretty colours! Next time I have a wd2d+ session, I'll try to film it.

 

[johnwimberley]

Does that glow produce a tan?

Actually, what is happening is called chemoluminescence. When pyrogallol, the main developing agent in WD2D+, goes from an alkaline to acid environment, it gets so happy to glows for a few moment. So when you pour the stop bath into the developer it emits light for a short time. If you are tray developing and your eyes are fully dark-adapted, you can often see the negative light up when you place it in the stop bath. But fear not, there won't be any fogging as development is complete and has been stopped. To my knowledge, pyrogallol is the only chemoluminescent developing agent. Just another good reason to use pyro!

 

[keithwms]

Thanks John, nice to hear from the creator of this lovely developer and interesting phenomenon. And you are the first person to confirm that I am not crazy, so thanks for that

 

[johnwimberley]

A quick check of the dictionary corrects my spelling: it's "chemiluninescence". You're definately not crazy!