Bromoil and dichromate replacement

[Fabio Pasquarella]

Hello,

I'm new to the process and I'm looking for a dichromate substitute. I heard of diazidostilbene in carbon printing but it seems there isn't any info around for bromoil. I was wondering if anyone has successfully use it. Thank you

 

[TheToadMen]

What process are you thinking about? I never used dichromate in Bromoil printing.

http://www.picto.info/oildoc/jkv_Ebromoil.pdf

 

[Fabio Pasquarella]

What process are you thinking about? I never used dichromate in Bromoil printing.

they use dichromate for the bleaching/tanning stage in "Bromoil a foundation course" by D. Watkins, "The art of bromoil transfer" by D.W Lewis and in all other formulations I found

https://www.bostick-sullivan.com/cart/images/filemanager/uploads/bromoil bleach instructions.pdf

do you know an alternative process?

 

[NedL]

I think TheToadMen just forgot for a moment that dichromate is used to harden the gelatin in bromoil. I'm not aware of anyone coming up with a successful alternative.

Here's an earlier (there was a url link here which no longer exists).

There are some potential alternatives if you want to use enlarged negatives (negative is same size as final print), but one of the advantages of bromoil is that you can enlarge a small negative onto the paper.

 

[Fabio Pasquarella]

I'm not aware of anyone coming up with a successful alternative.
Here's an earlier (there was a url link here which no longer exists).

thank you NedL, unfortunately it seems that way :/
Anyway do you think DAS could replace dichromate as a tanning agent? I'm not a chemist but I found some references here:

https://www.google.com/patents/US2663640

"The new light-sensitive layers, produced in accordance with the present invention containing sufficient quantities of diazidcstilbene compounds in place of chromates as the tanning agent..."

so I would give it a try, but since I've never made bromoil prints I probably wouldn't be able to judge the result.

 

[NedL]

I don't know anything about Diazo except that some folks have used it successfully for carbon transfer. My ( possibly faulty! ) memory is that Sandy King tried it and found that it could work, but decided it wasn't worth the learning curve to figure out all the details of working with it when dichromate works so well. There's a (there was a url link here which no longer exists).

But again, I think this might work for full-sized negatives, but might not work for enlarged prints like bromoil uses.

My own personal opinion on using dichromates is that I am not fearful about using them ( with appropriate care ) but I don't want to deal with waste products, and am not qualified to know how to safely dispose of them.

 

[Fabio Pasquarella]

Nedl I agree, infact I have no problem at all to use dichromate. The point is that here in Europe it will be banned very soon and I need to look for a replacement. Thank you for your help though

 

[TheToadMen]

I think TheToadMen just forgot for a moment that dichromate is used to harden the gelatin in bromoil. I'm not aware of anyone coming up with a successful alternative.

It's been a while since I made bromoil prints, but I can't remember using dichromate. I'll check my notes or ask the teacher what we did use back then. And it it was dichromate, I'll ask him for alternatives (if any).
I'll get back to you.

 

[Fabio Pasquarella]

Hello,
here are some updates. I've just talked to Sandy King who claims diazidostilbene is "used in some carbon printing where the relief is developed on a plastic support, but it can not be used with carbon where the relief is developed on a traditional gelatin or albumen sized paper. This is because diazidostilbene leaves a heavy yellow stain on paper supports that is impossible to remove".
I keep on searching for a solution.

 

[Gerald C Koch]

Unfortunately there are times when dichromate must be used. Wear nitrile gloves when working with the solid and solutions and a face mask and dust filter when using the solid.

 

[Fabio Pasquarella]

Unfortunately there are times when dichromate must be used. Wear nitrile gloves when working with the solid and solutions and a face mask and dust filter when using the solid.

no problem in doing that, the point is that in Europe it will be banned very soon and I need of a replacement.

 

[Gerald C Koch]

no problem in doing that, the point is that in Europe it will be banned very soon and I need of a replacement.

AFAIK there is no replacement. I would suggest continuing to search for other sites on the web.

You might also see if the EU provides any exemptions for small quantities. Also do a bit of research commercial on uses for dichromates. I believe it is used in metal plating and finishing. That might suggest other sources.

 

[nmp]

Just curious....How about using something like alum that is traditionally used in hardening fixers etc. here. Is it not as effective as the dichromate for the purposes of bromoil?

 

[NedL]

The key for bromoil is that it must harden the gelatin deferentially: hardening where there is silver, but leaving the gelatin soft elsewhere. Then the paper is soaked in water and the soft gelatin absorbs more water and repels the oily ink when it is applied. The gelatin that's been hardened will accept the ink. I think alum would harden the gelatin all over.

 

[nmp]

The key for bromoil is that it must harden the gelatin deferentially: hardening where there is silver, but leaving the gelatin soft elsewhere. Then the paper is soaked in water and the soft gelatin absorbs more water and repels the oily ink when it is applied. The gelatin that's been hardened will accept the ink. I think alum would harden the gelatin all over.

Got it, I think. Correct me if I am wrong. The dichromate here is acting more in its physio-chemical capacity, in conjunction with Silver, rather that its photo-chemical capacity as it would be in gum, carbon etc. Where there is silver, the gelatin becomes less hydrophilic and more receptive to the oil paint.

 

[NedL]

I think that's exactly right.

 

[BJ68]

You might also see if the EU provides any exemptions for small quantities. Also do a bit of research commercial on uses for dichromates. I believe it is used in metal plating and finishing. That might suggest other sources.

The problem is:

a) There is no exempt-rule even for small quantities
b) The use itself will be forbidden...see art 56 of REACH http://www.reachonline.eu/REACH/EN/REACH_EN/article56.html
c) So far I know until now no authorisation is granted even there are some applications for authorisation see https://echa.europa.eu/addressing-c...ions-for-authorisation-previous-consultations and https://echa.europa.eu/addressing-chemicals-of-concern/authorisation/applications-for-authorisation
d) I contacted a lawyer who is specialized in REACH and chemical law....his estimate to look over the case (Applying for authorization) was 10 working hours (circa 3000 Euro). There is no certainty that the authorization will be granted, because you have to proof that e.g. you can handel the risks or that the "socioeconomic benefits outweigh the risk to human health arising from the use of the substance and there are no suitable alternative substances or technologies in terms of their economic feasibility."
e) That means you need expert assessment which will be very expensive and a financial overkill.

Bj68

 

[RauschenOderKorn]

For the German speaking folks, the following link may of interest:

Dead Link Removed

Legal and safety restrictions apply, so don't do anything stupid!

 

[Wayne]

Hello,
here are some updates. I've just talked to Sandy King who claims diazidostilbene is "used in some carbon printing where the relief is developed on a plastic support, but it can not be used with carbon where the relief is developed on a traditional gelatin or albumen sized paper. This is because diazidostilbene leaves a heavy yellow stain on paper supports that is impossible to remove".
I keep on searching for a solution.

A clearing bath is used in gum diazo printing. I have no experience with either process so I don't know if this is an appropriate comparison or not, but I too am still curious about dichromate alternatives.

https://www.alternativephotography.com/gum-diazo-printing-v1-4/
Clearing and final washing

The Diazo stain can be removed with a diluted bath, made up by mixing the two stock solutions given below6:

Stock Clearing Bath A:

• Water (at 44C°) 930 ml
• Potassium Permanganate 6 g
• Sodium Chloride (Table Salt) 14 g
• Glacial Acetic Acid 25 ml
• Water to make 1 liter

Stock Clearing Bath B:

• Water (at 44C°) 940 ml
• Sodium (Meta) Bisulfite 30 g
• Sodium Sulfite 30 g
• Water to make 1 liter

 

[Máx Arnold]

Hey...
I recently discovered the bromoil transfer process and I want to try it. I don't live in the EU so getting dichromate is not the problem. I am the danger in here, since I'm such a mess with chemicals...
I wanted to ask:
What about using a tanning developer instead? Like pyrocatechol or something like that.... That would harden the gelatin differentially, wouldn't it?
I think NedL used to investigate some alternatives for generating the so desired "gelatin matrix", like the chiba system. Sadly, all the postst from that era on the forum are full of "dead link(s) removed". So I can't really know any more than what was mentioned on APUG.

Thanks in advance.

 

[73764]

I started this thread a few years ago https://groups.io/g/carbon/topic/16426792. Link to the correct pdf in that thread doesn't seem to work but it's available here: https://archive.org/details/DTIC_AD0274200.
Quote from p. 10-11:
"The Gros patents describe a process by which a reversal image transfer is effected. When a silver negative is immersed in an ethereal solution of hydrogen peroxide, there is an adsorption of the peroxide to clear areas on the negative. Catalytic decomposition of the peroxide takes place in proportion to the density of the silver areas. The negative is withdrawn from the peroxide after an unspecified period and placed in contact with a receiver layer containing ferrous salt and gelatin. This permits a peroxide-ferrous reaction, the result being an "image-wise" production of ferric ion, accompanied by insolubilization of gelatin where ferric ion is formed. Washout reveals a water-insoluble image which is a reversal of the silver image on the negative. (...) Certain organic developers could replace the ferrous salt in the receiver layer. Those found satisfactory were hydroxylamine hydrochloride, metol, azidol (2.4 diamino phenol dihydrochloride). Later tests added thiourea and ascorbic acid to the list."

I doubt it would be that simple if it could work at all but it would be cool to make bromoil matrix out of paper negative with hydrogen peroxide and vitamin C.

 

[Robert Maxey]

Hello,

I'm new to the process and I'm looking for a dichromate substitute. I heard of diazidostilbene in carbon printing but it seems there isn't any info around for bromoil. I was wondering if anyone has successfully use it. Thank you

Here is a description of the compound you referenced above:

https://www.phototypie.fr/en/reactifs-photosensibles/14-diazidostilbene.html

"It can be used for the photographic processes in which potassium dichromate is traditionally used. The results are similar to those obtained with dichromates .The diazidostilbene is known to work with gelatin, carboxymethyl cellulose, polyvinyl acetate, casein and probably many other substances.It must be handled, and mixed under a safelight used as very sensitive to light (peak sensitivity at 335nm).

Unlike dichromate, DAS is non-toxic, non-carcinogenic, has no dark reaction, and colloids with which it comes in composition can be stored for long periods keeping intact their ability photosensitive. After UV exposure, the impressions made using DAS require a sensitization process in 2 steps : The first bath is a dilute solution of potassium permanganate or hydrogen peroxide in brine and the second bath is an ordinary sulfite / metabisulfite.

The reason I am looking into this compound is because it works with PVA and it exposes well with LEDs 2 335nm. It works well at around 2.5% chemical to water.

Also, in some countries, Dichromates are listed as being carcinogenic, Mutogenic and Toxic for reproduction. I fear the US might also (if not already done so) eventually ban it. To be clear, no I have not tried it. The compound has been mentioned to me a number of times because I have been looking for other specialized sensitizers for 3 years. which makes me wonder. Testing is the key.

The company referenced above says the results are "similar"

Keep us posted, Bob

 

[Wayne]

What about using a tanning developer instead? Like pyrocatechol or something like that.... That would harden the gelatin differentially, wouldn't it?
.

This is briefly discussed in another thread here with the more experienced workers believing that it probably wouldn't work but IIRC apparently no record of anyone having tried it. I experimented with a hydroquinone print developer toward that end but since I have sporadic darkroom access I have not followed through beyond that. You should be able to find that other thread or threads searching on the topic and my name. Ahh, try this one https://www.photrio.com/forum/threads/avoiding-potassium-dichromate-in-bromoil-process.93439/

 

[Máx Arnold]

apparently no record of anyone having tried it

Like always... haha

Thank you so much!

 

[Wayne]

Like always... haha

Thank you so much!

You can be the first. One reason I haven't pursued it very hard is that I've never done bromoil so it will be harder for someone like me to determine whether it didn't work because it doesn't work, or because I did something else wrong or poorly. It really needs someone with bromoil experience to try it but if someone already does bromoil with dichromate they have no reason to. So nobody does it.