Chromium Intensifier

mrred · Oct 16, 2013

I found this recipe on the net.

distilled water -- 75 ml
potassium dichromate -- 9 gr
hydrochloric acid -- 6.5 ml (more to reduce intensity)
add cold water to make 100 ml

I tried it and it works quite well. My question would be how long would this stuff last on the shelf?

Gerald C Koch · Oct 16, 2013

This formula is intended for one-time use. As such it has little reserve capacity and should not be saved. For safety reasons not something that should be kept on the shelf.

mrred · Oct 16, 2013

What I stated is the stock formula. It is then mixed 1:10 for use, and that is one time use.

mrred · Oct 16, 2013

Outside of it containing dichromate and hcl, does it create an additional combined hazard?

MartinP · Oct 16, 2013

What would be the advantages of this formula over the more standard selenium-toner, for negatives? (I'm assuming that you were using it on film, rather than paper).

Ian Grant · Oct 16, 2013

MartinP said:
What would be the advantages of this formula over the more standard selenium-toner, for negatives? (I'm assuming that you were using it on film, rather than paper).

It's very much stronger in it's intensification.

Ian

mrred · Oct 16, 2013

+1 and you can repeat it. I also had everything to make it.

Ian Grant · Oct 16, 2013

In two parts the Chromium Intensifiers last decades. Ideally you need a Bichromate solution Part A and a weak HCl solution as Part B.

Ian

mrred · Oct 16, 2013

I guess the magic approach is to split them up and do 1:1:20. Thats workable. It's just not something you would use every day, hence my question.

nworth · Oct 18, 2013

That formula is for a ready to use, one-shot intensifier. It works well. You bleach the negative in the solution and then redevelop in something like Dektol.

Kodak IN-4 chromium intensifier
Water 1 l
Potassium dichromate 90 g
Hydrochloric acid (conc) 64 ml
Dilute 1:10 for use. Bleach negative thoroughly in the above solution. Wash 5 minutes, then redevelop in room light in a non-staining developer without excess sulfite. Degree of intensification may be controlled by degree of redevelopment. After redevelopment, rinse negative, fix, and wash. Repeat process for greater effect.

mrred · Oct 18, 2013

And that would be a formula for 10 times more, and not answering the question (already answered anyway)....

cliveh · Oct 18, 2013

mrred said:
potassium dichromate -- 9 gr

Nasty stuff, take care.

mrred · Oct 18, 2013

Driving a car will get me killed faster. Both are safe when operated safely and the car has a greater possibility of being an exception.

richard ide · Oct 18, 2013

AFAIK it is a hexavalent chromium compound. Look up the MSDS. Extremely toxic and recommended usage under a fume hood and no dumping down the drain.

mrred · Oct 18, 2013

And I would repeat my last answer. I did say safely. Maybe now you can understand what I think of people with their ability to drive cars safely.

Gerald C Koch · Oct 19, 2013

After use the dichromate solution should be mixed with a sodium sulfite solution. This reduces any Cr (VI) which is very toxic to Cr III) which is less toxic before discarding. The yellow orange color of the dichromate will change to green.

richard ide · Oct 19, 2013

Thanks Gerald. Information appreciated.

ArgentixCa · Oct 20, 2013

Hi mrred
AFAIK, I would rather work with your product than drive in Montreal. For sure it will kill you faster to drive there.
Each and every chemical products we use can be dangerous if used improperly.
It is our responsibility to use it the way it is intended for.

And yes, your recipe looks like the one I had in my old Encyclopedia of photography, Focal Press, printed in 1972.

Best regards,

mrred · Oct 20, 2013

I've been give lots of correct advice to be safe when using dichromate. I am not sure why it was assumed I didn't, but thanks all the same. It was good advice and reaffirmed what I was doing.

It's no secret the contempt I have for bad drivers. Most show high degrees of being inattentive at the best of times. For the record, I don't drive and probably never will (and I am over 50 now). If I treated my chemistry like I see most other people drive, I would have been dead a long time ago.

Please remember this when you are in your "lab" on on the "road".

Oh, Montreal has the worst drivers I have ever seen. They seem take great pride with the disrespect they give others on the road. I'm glad they don't all have darkrooms.

mrred · Oct 20, 2013

Rant over...

Chromium Intensifier

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