[Alt-photo] Re: casein and Ferrari red

[Loris Medici]

Wow, great conversation guys! Very useful insight below... Thanks!


2013/5/14 Marek Matusz <marekmatusz at hotmail.com>
>
> SO it seems that is not the pigments, but the additional gum that you mix
with casein that is not compatible. I will test that with my solutions as
well.
> On the subject of fresh vs. aged casein solution.
>
> The reason that I let my solution age for at least few days is that when
freshly mixed it is very viscous and coats differntly. As the solution ages
it becomes less viscous and eventually after a few days or a week it
becomes the consisteny of 14baume gum. The change continues but at a much
lower rate and I continue to use the solution for months
>
> I ended up with grainy prints when using freshly made solution (same or
next day). Perhaps I could alter the concentrations, add more water, etc,
but did not bother to look into it some more. On the other hand I actually
liked the grainy look of the print a lot and wated to follow with tricolur.
>
>
>
> > From: christinazanderson at gmail.com
> > Date: Tue, 14 May 2013 09:18:48 -0600
> > To: alt-photo-process-list at lists.altphotolist.org
> > Subject: [Alt-photo] Re: casein and Ferrari red
> >
> > Dear All,
> >
> > So glad all of you use that color with no problem!!
> >
> > Here's a picture of the coagulation just in case you think I'm nuts :)
I've also put at the same place my latest "two best friends" for colloid
printing.
> >
> > http://christinaanderson.visualserver.com/Text_page.cfm?pID=1953
> >
> > After I made the post, I continued casein printing and an hour later
when I looked at the mix the curdle had subsided into a usable solution! It
was smooth again in other words. So now I was really puzzled.
> >
> > I even tested it in a print and it worked fine. So thank heavens PR254
is still fine.
> >
> > So I went and got a tube of PR254 and then my stock solution (PR254
mixed in gum arabic which I had used) and tried both. The PR254 tube worked
fine enough, with a slight thickening. The stock solution (1 tube of PR254
mixed in 45ml gum arabic) immediately curdled the casein.
> >
> > So I took my Daniel Smith gum from the gallon container and mixed it
into the casein and immediate curdle.
> >
> > I then tested gum arabic against water to see if it was added liquid
and the water did not curdle it.
> >
> > Thus I have ascertained that gum in tandem with my casein solution is
most likely the issue (it was 1/4 tsp of gum/pigment in 1 T casein), but I
have never seen this happen before with all the layers I have done, since I
started mixing up casein/pigment at time of use. I have to mix a new batch
of casein today so I can mix fresh with the gum again and ascertain if the
age of the casein is an issue, too.
> >
> > Marek, the nickel azo yellow working strength solution (I mixed 500ml
of it, like I usually do gum arabic and the gum/pigment solutions last
forever) precipitated hard chunks after 1 or 2 weeks. They were not usable.
Hard curds, not soft curds like yesterday. But I have always used this
pigment at time of use. I mix a tube of it in 45ml water to dilute it (it
is SO strong) and then I use 1/4 tsp of that to 1 tsp-1T casein. It's just
such a concentrated pigment I have a hard time measuring out the right
"pea" size, but that's just me.
> >
> > My casein doesn't go bad, because I use either thymol or now sodium
benzoate (1/4 tsp per 100ml solution) as a preservative. In the past, it
would start thickish and then get watery over a period of time. Once I did
not preserve it and left it in a warm car. Stupid me. What a smell. I threw
all away, 250ml bottles and solution.
> >
> > Marek, you say you don't use your casein for a couple weeks after
mixing. How come? I literally mix 'n go.
> >
> > Guido, so glad to hear from you!! You haven't posted in a long time!
You might not know that you are quoted in my book! I was so surprised at
your short exposures (20-30 seconds) when I first read them on an alt post
you made years ago, but actually, this whole last period of time I have
been exposing all layers at 45 seconds. Incredibly fast.
> > Chris