[Alt-photo] Dichromate Poisoning

Jim Patterson jimbobnola at cox.net
Mon Oct 30 21:09:12 UTC 2017


Correction:  polyethylene glycol diacrylate 

Sent from my iPhone

> On Oct 30, 2017, at 11:17 AM, Kelcy Patterson via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> 
> Hi Richard and Larry,
> 
> Cerium iii Chloride hardens gelatin moderately, and Cerium iv Ammonium Nitrate hardens gelatin strongly.  I reconfirmed that yesterday by coating a 5% solution of each on a strip of B&S carbon tissue, then soaking it in warm water.  The cerium iii was hardened down to the base.  The cerium iv was very hard, like when you over expose a dichromate carbon tissue.  I tried Cerium iv Ammonium Sulfate dihydrate, complexed with Ammonium Citrate, dibasic  (1:2 by wt) with a CAS concentration of 5% and AC 10% solution on a strip of carbon tissue.  I then exposed it to UV with a strip of black paper down the middle.  I was surprised to find that the unexposed area was hardened, and the exposed area dissolved away.  ? possible to do a direct positive process.  I will work on that later.  I did develop a type of carbon process by coating paper sized with waxy corn starch, coating with CAN in very dilute nitiric acid, drying, exposing the paper through a positive to UV, then soaking the C tissue in 2% oxalic acid, mating, developing as usual.
> 
> The most relevent sources I used for GB alternates were the following:  Google these:  Polymerization system using Ceric salts, Photoinitiation cerium iii sulfite, Eosin Y photopolymer.  These processes are free radical polymerization.  I have avoided Acrylic Acid as it is toxic and carcinogenic.  I have used as binding polymers: gelatin, fish glue, PVP, PVAl, methyl cellulose, and gum Arabic.  I have used as monomers and crosslinkers:  polyethylene diacrylate, 400; N-vinyl pyrrolidone; N,N-methylenebisacrylamide, and diacetone acrylamide.  My best results are with PVP K60, NVP, and MBA.  I am planning to post a print soon and you can judge if it is worthwhile.  Note that the Eosin Y is sensitive to green light, not UV, so you can use a bright LED light or sunlight.
> 
> Jim Patterson, New Orleans
> 
> 
> 
> On October 27, 2017 at 4:15 PM Richard Sullivan <sullivan8486 at gmail.com> wrote:
> 
> 
> From CameraCraft 1929 pg 593
> The OCR scan is a bit weird!
> 
> The Carbon Process
> Dr. E. J. Tritton recently read before
> the Royal Photographic Society (G. B.)
> an exhaustive and rather technical paper
> on methods of increasing the printing
> speed of bichromated gelatine, inasmuch
> as this includes the printing of carbon
> tissue and the carbon process still holds
> an important place in professional portrait photography, its practical application will interest carbon workers.
> "If a small quantity of a cerium salt
> for example cerous chloride is added
> to the usual dichromate bath, the speed
> of the resulting carbon tissue is considerably increased, while the subsequent
> development, and other operations remain
> exactly as usual. A suitable formula for
> a sensitizing bath is:
> Pot. dichromate pure cryst 2% parts
> Cerous chloride 10% sol 2 parts
> Water 100' parts
> "It is most important to note that only
> pure dichromate should be used, and no
> ammonia must be added tc it.
> "The disadvantage of this process is that
> it does not keep well. A much better
> method is to sensitize the tissue in plain
> dichromate, e. g., the above formula with
> the cerous chloride omitted, and then to
> give only one-third of the exposure that
> would be required under normal circumstances.
> "For mounting, instead of soaking the
> tissue the normal way in water, a 2%%
> solution of cerous chloride is used. When
> the tissue is limp to the correct extent in
> this solution it is mounted on the soaked
> transfer paper in the normal way, left between blotting boards 15 minutes, and then
> developed in hot water. A full strength
> image is then attained without any other
> variations in the process. The time of
> soaking the tissue in the cerous chloride
> solution has practically no inlluence on
> the density or gradation Of tin- image obtained, and neither is the exact concentration of tin- Quid of great importance, but
> with both very weak and very strong solutions, such as 1% to 4'/t, there is a tendency to flatness. The cerous chloride solution can be used over and over again,
> and also a used solution can be stored and
> then used again, despite the fact that it
> gathers dichromate from the sensitive tissue, after a time however the resulting
> prints are found to be slightly flatter.
> "Obviously by employing this procedure
> the normal keeping qualities of the tissue
> are retained, but it is equally obvious that
> any tint or fog that may be on stale tissue
> will be just as much intensified as the
> exposed image. Hence only fresh tissue
> should be employed."
> 
>> On Fri, Oct 27, 2017 at 1:19 PM, Larry Ogrodnek via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org mailto:alt-photo-process-list at lists.altphotolist.org > wrote:
>> 
>> Hi Jim,
>> 
>>    I'm interested to learn more about these alternative sensitizers -- do you
>>    have any text/links/reference you could send on their use?
>> 
>> 
>>    thanks!
>>    larry
>> 
>>    On Thu, Oct 26, 2017 at 10:42 AM, Jim Patterson via Alt-photo-process-list <
>>    alt-photo-process-list at lists.altphotolist.org mailto:alt-photo-process-list at lists.altphotolist.org > wrote:
>> 
>>> Hi All,
>>> Being an occupational physician I am aware of the risks of Chromium VI.
>>> On the certification exams they always have questions on chrome holes,
>>> perforated nasal septum, and nasopharyngeal and sinus cancer.
>>> 
>>> I have been a student of Chris and she preaches safe handling and personal
>>> protective equipment.
>>> 
>>> In the past 2 yrs I have been experimenting with alternate Sensitizers and
>>> colloids.  The most promising at the moment are Cerium IV Ammonium Sulfate
>>> and Eosin Y.
>>> 
>>> Both of these harden gum Arabic, gelatin, fish glue, cellulose gum, PVP
>>> and others.  I am not saying they are better than GB, but are alternatives.
>>> 
>>> Jim Patterson, New Orleans
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Oct 26, 2017, at 2:12 AM, Charles Berger via Alt-photo-process-list <
>>> alt-photo-process-list at lists.altphotolist.org mailto:alt-photo-process-list at lists.altphotolist.org > wrote:
>>>> 
>>>> My post was prompted by the declaration of a highly regarded arts
>>>> educator/author that if/when dichromate was restricted here, as it is in
>>>> the EU, she had a sufficient supply for her and her students to continue
>>>> using it indefinitely.
>>>> 
>>>> This cavalier attitude towards the use of dichromate for the sake of
>>>> photographic printmaking is ill advised as it implies that the dangers
>>> are
>>>> not to be taken seriously.
>>>> 
>>>> Responses ranged (with a few exceptions) from the abusive (and idiotic)
>>>> advise not to “lick the top of Cherry wood table” to a non-sequitur
>>>> description of the installation of seat belts in a 1956 Oldsmobile.
>>>> 
>>>> The point I was making is that there is little discussion of dichromate
>>>> poisoning and a lack of detailed information (beyond “wear gloves”) on
>>> its
>>>> safe use in the current literature on alternative photo processes.
>>> Perhaps
>>>> Marton was correct when he wrote about “The Dichromate Disease” in The
>>> *Photo
>>>> Oleograph Process*(1900) that “Rich living and alcoholic stimulants, seem
>>>> to foster this peculiar ailment”,  and thus all we need to do is avoid
>>> such
>>>> behaviors to safely work with dichromate.
>>>> 
>>>> Why are so many of you upset about discussing this? And why do you feel
>>>> compelled to defend this lack of concern and to dismiss any in-depth
>>>> information on the subject as “scare tactics?”
>>>> 
>>>> Full disclosure:  I have recently been exploring with Chris the creation
>>> of
>>>> a book (or series of books) describing non-toxic alternatives to historic
>>>> photographic printmaking. Her statement caught me completely by
>>> surprise. I
>>>> am confident that Chris is truly concerned with the health and safety of
>>> us
>>>> all, but this dismissive attitude is unfortunate.
>>>> 
>>>> Charles
>>>> _______________________________________________
>>>> Alt-photo-process-list |http://altphotolist.org
>>> 
>>> _______________________________________________
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