RE: old vs. new cyanotype

Tween 20 , is also known generically as Polysorbate 20

HS-No. 34021300
 Mr ca. 1 200 * CAS-No. [9005-64-5]

(Polyoxyethylene sorbitan monolaureate, n ca. 20

I don't think you can make it yourself.

I have read that some people use photo-flo, Edwal LFN, jet-dry
(for dishwashers) and some have used dishwashing liquid as a substitute
for tween. They are all surfactants. I don't what the pH of photo-flo or
jet-dry is. If they are alkaline it may cause problems with cyanotype.

I think tween has a neutral pH - but I don't know for sure.

I googled peptisation and surfactant and discovered the rubber industry
has peptisation and surfactant issues.

This industry uses zinc soaps as a surfactant:

Various zinc soaps such as zinc stearate, zinc laurate, zinc tallowate,
zinc naphthenate, zinc resinate, and zinc 2-ethylhexanoate (ZEH) are currently
used in the rubber compounds as additives.

Gord

On Fri, 11 Jun 2004, Bob Kiss wrote:

> DEAR GORDON & LIST,
> Is Tween something I can prepare from it's ingredients? Does anyone know
> what the ingredients are? Living here in Barbados it is a long, arduous
> process to order things from overseas but many basic chemicals are available
> through the local labs. Please let me know.
> CHEERS!
> BOB
>
> -----Original Message-----
> From: Gordon J. Holtslander [mailto:holtsg@duke.usask.ca]
> Sent: Friday, June 11, 2004 11:48 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: old vs. new cyanotype
>
>
> Hi:
>
> I've been working on summarizing things from Ware's cyanotype book -but
> this is too much.
>
> I'll do an essential summary of the chemical differences between classic
> and cyanotype II.
>
> First - Ware states that cyanotype or prussian blue is a chemical
> structure with some variabilty, depending on how it is prepared. Its a
> squarre crystal lattice with some variabilty as to what is in the lattice.
>
> The lattice structure itself is capable of containing other compounds.
>
> The classic cyanotype forms a crystal lattice that contains pottasium
> within the lattice. This structure suffers from what is called
> peptization. Peptization is the formation of a suspension of very fine
> minute particles in water.
>
> classis cyanotype does not really disolve in water - it is a very fine
> suspension of fine particles. The particles are so small that they cannot
> be seen - so it appears that they are dissolved, but they are not.
>
> Apparantly these particles are so fine that they often do not bind to
> paper - they wash away in the processing. Ware recommends the use of the
> surfactant tween - presumably to aid in the binding of classic cyanotype
> particles to paper.
>
> Cyanotype II creates a form of prussian blue without significant
> pottasium in the crystal structure. It does not suffer from petisation to
> the same extent as classic cyantype. The reason that it is fiddly to
> create is that one of the reactants (don't recall the name offhand) is not
> commercially available. The process of heating up solutions and filtering
> them creates the necessary compound for cyanotype II.
>
> Cyanotype II presumably is better able to bind to paper than cyanotype
> classic.
>
> I would guess if you are able to do classic cyanotype without significant
> image "washing away" in processing, then cyanotype II holds no advantage.
>
> If you have a paper that you have to use and classic cyanotype washes
> away, try cyanotype II - but maybe try adding some tween to classic
> cyanotype first.
>
> Gord
>
> On Fri, 11 Jun 2004, Christina Z. Anderson wrote:
>
> > A while back we were discussing the two cyanotype formulas. I reported
> this
> > weird thing happening with the new cyanotype: the print would look
> perfect
> > but all highlights would be lavender. I thought my solution was fogged, so
> I
> > ordered a new batch from Photographer's Formulary.
> >
> > I mixed up the solution yesterday. I do say it is way more work to mix
> than
> > the traditional formula, but still, manageable. The Formulary kit is so
> > wonderful because everything is measured out in packets for you. $20 for
> > 100ml.
> >
> > You have to heat distilled water, add the green crystals of ferric
> ammonium
> > oxalate, pour in the bottle of dichromate solution, and then (the only
> putzy
> > step) grind up the potassium ferricyanide crystals to a yellow powder.
> This
> > I do by leaving it in the bag it comes in, and rolling it with a rolling
> > pin. No mess, no dust. Then you have to add this to the mix and let sit
> in
> > the dark for an hour. Then pour it thru a coffee filter and add water to
> > make 100ml. Not bad, but still, one vote pro traditional.
> >
> > My old (very) solution was not fogged, because I still got the lavender
> > highlights. I figured out what it is, too. Luckily I was making salsa.
> > Not having my photo chemicals here, I squeezed some lime juice onto the
> > lavender highlights and presto, they turned blue. Thus, the lavender is
> > exposure, but in an alkaline environment. I feel like the Martha Stuart
> of
> > kitchen photography.
> >
> > Hence, Fabriano Artistico is probably not a suitable paper for the new
> > cyanotype unless you dink around somehow. I tried coating it with oxalic
> > acid before printing, and that did not work. One more vote for the
> > traditional.
> >
> > Other than this, still no wash off, still deep blue, still looks perfectly
> > fine under tricolor gum, because the acidity of the dichromate in the gum
> > layers must do what the lime juice did, takes care of the lavender.
> > Chris
> > PS BTW, Tom Ferguson, even with the paler nickel titanate layer in the
> Wang
> > process, as opposed to the cadmium yellow, I still did not need to reprint
> a
> > yellow layer--it was plenty yellow.
> >
> >
>
> ---------------------------------------------------------
> Gordon J. Holtslander Dept. of Biology
> holtsg@duke.usask.ca 112 Science Place
> http://duke.usask.ca/~holtsg University of Saskatchewan
> Tel (306) 966-4433 Saskatoon, Saskatchewan
> Fax (306) 966-4461 Canada S7N 5E2
> ---------------------------------------------------------
>

---------------------------------------------------------
Gordon J. Holtslander Dept. of Biology
holtsg@duke.usask.ca 112 Science Place
http://duke.usask.ca/~holtsg University of Saskatchewan
Tel (306) 966-4433 Saskatoon, Saskatchewan
Fax (306) 966-4461 Canada S7N 5E2
---------------------------------------------------------
Received on Fri Jun 11 11:03:11 2004