[alt-photo] Re: On working with hydrochloric acid

[Kerik Kouklis]

Thanks for posting this Harlan!  I would encourage the use of oxalic acid for treating paper. I've been using this approach for well over 10 years with many hundreds of pt/pd prints and it works extremely well. 

Kerik
www.kerik.com

On Feb 16, 2013, at 7:14 AM, Harlan Chapman <hchapman at coastside.net> wrote:

> A gentle warning on a sneaky little hazard in using hydrochloric acid
> (muriatic acid):
> 
> The acidic component is a gas, hydrogen chloride (HCl). Even dilute
> hydrochloric acid will liberate the gas into your working environment.
> Within reason this doesn't present a serious toxicity hazard and with good
> ventilation you will be fine - hydrochloric acid is surprisingly friendly
> to work with considering it's strength. But nearly any metal (aluminum,
> iron, copper, even most stainless steel alloys commonly used) in your
> entire workspace, even across the room, will begin to corrode. The
> corrosion will be slow, insidious and damaging. Once noticed you'll find it
> everywhere. So don't work with HCl in a darkroom space that may include
> valued metal objects like clocks, cameras, dry mount presses, cutters…
> Don't use it in a stainless steel sink unless you know it is an
> HCl-resistant alloy. And don't store concentrated (even dilute)
> hydrochloric acid solutions inside unless double or triple packaged as even
> the best sealed bottle will likely leak fumes slowly into your storage
> space and destroy it.
> 
> Mix hydrochloric acid, use it, store it, and dry paper treated with it
> freely outside.
> 
> The volatile corrosiveness of HCl largely is not shared with most other
> acids commonly used in photographic/printing processes.  Oxalic, acetic,
> citric, dilute sulfuric, and dilute nitric, are OK, they won't liberate
> undetectable vapors that slowly chew on metals throughout your workspace.
> 
> Happy printing,
> 
> -Harlan
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