Re: Please complete this tintype formula for me:

Excellent! Thanks! Is there any chance that you can comment on the
reactivity of these chemicals to plastic? I found some great plastic trays
that I wanted to process in but I'm not sure if I'll wind up with a
carcinogenic puddle on my darkroom floor.

-Jon

----- Original Message -----
From: "Etienne Garbaux" <photographeur@softhome.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Friday, July 23, 2004 10:54 PM
Subject: Re: Please complete this tintype formula for me:

> Jon asked about tintype:
>
> > Sensitizer: Silver nitrate (what dilution?)
> > Developer: ???
> > Stop: Water (2 baths?)
> > Fix: Potassium Cyanide (4%?)
> > Varnish: (???)
> >
> > What is the process of plate preparation (I've read they should be
painted
> > black first and then sensitized?) and what metal is best to use?
> >
> > Thanks,
> > Jon
>
> I haven't seen the Nat Geo site, but judging from the silver nitrate dip
> and the cyanide developer it appears that you are doing real collodion
> tintypes. Excellent!
>
> Plates are usually thin steel (0.010"-0.030") that have either been dipped
> in asphalt (roofing tar) thinned in mineral spirits, drained, then baked,
> or dipped in black lacquer, drained, and then baked.
>
> A 9-12% silver nitrate solution will work fine. The developer should be a
> solution of ferrous sulfate (sulphate if you're in Great Britain) with a
> bit of acetic acid added. You use just enough to cover plate. Only this
> inorganic developer makes the proper silvery-white silver deposits that
> ambrotypes and tintypes require. If you're a slow exposer, a bit of
> alcohol in the developer will re-soften the collodion and allow better
> penetration. I generally use a running water rinse followed by a
distilled
> water bath. Potassium Cyanide works OK at 1% (see the site link below),
> although 2-5% is more common. You need a good rinse after fixing,
> finishing with distilled water again. Traditionally, sanderac varnish
(gum
> sanderac in alcohol) is used. I have also used both shellac and clear
spar
> varnish with good results. Collodion is tough once it is dry, so, pretty
> much anything will work. The varnish is poured on and run around, then
> drained off a corner, just like coating the plate.
>
> Here is a page with typical ambrotype formulae:
>
> http://www.companyphotographer.com/html/formulas.html
>
> I recommend the rest of his site, as well.
>
> Best regards,
>
> etienne
Received on Sun Jul 25 20:45:27 2004