[Alt-photo] Re: Sulfamic Acid for Paper Acidification

[Christina Anderson]

Dear Serdar and Loris, etc.
This is really great news! Thanks for this discussion.
I just finished the semester as of yesterday (thank heavens for summer vacation), teaching a new batch of alt students. I had a discussion with a couple of my top students how to make the class better and one of the very important points they brought up is to limit the class to specific papers that are known to work--say, three--to make it easier. I would say that inappropriate paper is the top reason prints fail.
This semester I have been having the students (to save money) acidify their paper with the available stop bath in the lab and that has worked well enough to save them money and not introduce another chemical in the darkroom, but sulfamic acid is so cheap and readily available I could see having a container of that easiiy in the darkroom. I do not have HCL in there for obvious reasons.
It is so useful when people share their current top tidbit of the month to the list! Learning continues.
Serdar, do please share your notes on comparing the acids.
Chris

Christina Z. Anderson
christinaZanderson.com

On May 5, 2013, at 4:51 AM, Loris Medici wrote:

> Hi Serdar,
> 
> The evaluation depends on the process too; for instance, pt/pd is more
> forgiving about the acit pre-treatment operation but new cyanotype and
> argyrotype aren't. A paper treated in HCl would work OK with pt/pd but not
> OK witj new cyanotype or argyrotype. I'm personally more interested in the
> latter right now, I wasn't printing argyrotype much because it was more
> demanding (than vandyke) about paper, now that I make it work with many
> papers, I'm about to dump vandyke forever in favour of  argyrotype...
> Sulfamic acid pre-treatment made quite difference for me, because when it
> works (or you make it work with sulfamic acid), I find argyrotype being a
> lot better than vandyke in every aspect. (Dmax, tonal range and smoothness,
> hue...)
> 
> Regards,
> Loris.
> 
> 
> 2013/5/5 Serdar Bilici <sbilici at gmail.com>
>> 
>> Hi Loris,
>> 
>> I agree that there might be a sweet spot for dmax with HCl, but really
> why fiddle :)  Sulfamic acid has a great advantage at storage, it is not as
> corrosive as HCl to metals, so it is safer to work indoors, the prints have
> better dmax in comparison.
>> 
>> (You already know this bit, but I should include it for other readers)
>> When I made a research about sulfamic acid and its uses, I have found out
> that sulfamic acid is used in modern descaling systems to remove calcium
> deposits instead of HCl. Due it is less corrosive but it has equally strong
> acidic nature. As you said, probably sulfamic acid leaves the paper in
> better condition compared to HCl due to its less corrosive nature.
>> 
>> In terms of dmax, HCl treatment gave me the poorest results among the
> acids I have tested. Although, it was the right choice theoratically,
> (being a mono-acid, highly water soluble byproduct, fast reaction, good
> capacity) practically the results were not so appealing. Considering that
> the fumes of HCl would corrode the metals in the room it is used in time, I
> understand why it is not the most popular choice to acidfy papers. Proper
> ventilation is quite important when working with HCl (Dangerous chlorine
> gas release), on the other hand Sulfamic Acid + Calcium carbonate reaction
> produces only CO2 gas.
>> 
>> Compared to HCl it is a WIN-WIN.
>> 
>> Regards,
>> Serdar
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