Is this color prussian blue?

[Mythrill]

Hello, guys. I got some pigments from a friend so I could identify them, and one really looks like prussian blue. It has that dark, steel tone, and makes very delicated, grayed out tone. The thing is: I mixed it with an acrylic medium and it worked, but theoretically this is not possible (it shouldn't mix or it would release cyanide, killing me.)

By the way, I created the paint by mixing the pigment with the Golden gloss gel. The mixes were done with Winsor & Newton Artists' Acrylics.

So, here are a few questions:

1. Is the color shown here really Prussian Blue (Pb27?) If not, then what is it?
2. How well does homemade Pb27 behave in acrylics? I was wearing a mask because of the powder, but it was a simple mask. I didn't use a dispersion vehicle.
3. If Pb27 can actually be done in acrylics, how stable is it?

This is the photo, by the way:

[Gigalot]

Prussian blue is safe and non-toxic pigment. Do not worry about it`s toxicity as well as you newer worry about common salt (which can emit poisonous chlorine gas!). Only a professional chemist can do it.

You can decompose it in soda solution. The only thing you can get are Iron hydroxide and sodium ferrocyanide solution, both non-toxic chemicals. Acrylic binder also contains several soda or ammonium substance.

Einion told me about one discontinued non- alkaline acrylic Prussian blue paint, but I guess, it was polyvinyl acetate based paint. Polyvinyl acetate as a paint binder has a very bad lightfastness which is in use today in a cheaper housepaint only.

Manufacturers do not give us the exact formulation of their acrylic base. But anyway, alkaline sensitive or slightly water soluble pigments are not stable in "standard" acrylic paint.

[Mythrill]

Originally Posted by Gigalot

Prussian blue is safe and non-toxic pigment. Do not worry about it`s toxicity as well as you newer worry about common salt (which can emit poisonous chlorine gas!). Only a professional chemist can do it.

You can decompose it in soda solution. The only thing you can get are Iron hydroxide and sodium ferrocyanide solution, both non-toxic chemicals. Acrylic binder also contains several soda or ammonium substance.

Einion told me about one discontinued non- alkaline acrylic Prussian blue paint, but I guess, it was polyvinyl acetate based paint. Polyvinyl acetate as a paint binder has a very bad lightfastness which is in use today in a cheaper housepaint only.

Manufacturers do not give us the exact formulation of their acrylic base. But anyway, alkaline sensitive or slightly water soluble pigments are not stable in "standard" acrylic paint.

Thanks, Giga! I feel safe now to know that I can at least experiment with an acrylic binder and the pigment!

I also learned something very interesting with this: I think one local brand around is "enhancing" their Prussian Blue by mixing it with an Ultramarine Blue (or some Phtalo Blue) in their oil series. The undertone of this Prussian, even in high concentrations, is gentle and dull compared to my tube paint, which is a lot more bluish and livelier. As you can see on that sheet, that Prussian Blue mixed with my tube Ultramarine Blue has that a suspiciously blue undertone, even if the masstone remains identical.

As for the color, I suppose the lighter tints have faded a little now, but the masstone has not. Although it's too early to say, I do think the pure Prussian Blue is fading in acrylics: I think there are some white strands on the paint (the part mixed with white) that weren't there before. One interesting thing, however, is that the swatch mixed with just a little ultramarine blue looks far more stable than the pure pigment. (But again, I have to wait a few days – or even a few weeks – to confirm this.)

By the way, does Alizarin crimson goes through a dramatic color shift when dry? I tried it both in oils in acrylics – first oils, then acrylics. I also got a red pigment out of the tube that seemed to behave suspiciously like Alizarin Crimson - oranges were a bit earthy, it made a wonderful red... but within less than an hour, the colors in both media shifted to a maroon in masstone, and the pink mixes from white changed to a violet. The color also behaved strangely mixed with green: I forgot to take notes, but it didn't gray it down to a blackish undertone. There's one sample here I forgot to take notes of, and I believe that is the mix: it seemed to made a wonderful stable color mixed with it – I think it was an intense red-brown.

[karenlee]

Alizarin Crimson is one color that is never formulated in acrylic paint. I don't know why, some chemistry problem.

[Mythrill]

Originally Posted by karenlee

Alizarin Crimson is one color that is never formulated in acrylic paint. I don't know why, some chemistry problem.

Karen, I suppose it's almost never formulated in acrylic paint because it's very fugitive, and my guess is that many acrylic painters aren't as concerned about historical accuracy – at least not in the sense that they should use the exact same pigments as the old masters did. However, it seems making it *is* possible, as M. Graham produces it. Take a look:

http://www.dickblick.com/items/01601-3060/

[karenlee]

!!! Mythrill, that's the first PR 83 I've seen in acrylics. I remember reading it was a pigment that could not be used in acrylics. But there it is!

[Mythrill]

Originally Posted by karenlee

!!! Mythrill, that's the first PR 83 I've seen in acrylics. I remember reading it was a pigment that could not be used in acrylics. But there it is!

Color me surprised too! But many pigments that somehow couldn't be used in acrylics somehow can today. One is the famous (and, at least for now in my opinion, overrated) Perylene Maroon (PR179.) Look at how Dickblick describes it (link: http://www.dickblick.com/items/00414...#colorpigments.)

Properties
Perylene Maroon is a transparent, dull to moderately dull, deep red pigment. Its transparency makes it useful as a glazing color.[...] Perylene Maroon is not suitable for acrylics.

[Gigalot]

"Perylene pigments exist in a wide range of hues, they provide red, bordeaux, violet,
brown and black shades. The pigments exhibit excellent solvent stability, good
to very good migration stability in plastics, fastness to overcoating in paints, high
chemical inertness, and superior thermal stability. Only the basic compound, the
dianhydride of tetracarboxylic acid, is not fast to alkali.
As a group, perylene pigments offer high tinctorial strength. They are frequently
found to be appreciably stronger than quinacridone pigments. Moreover,
perylene pigments provide excellent lightfastness and weatherfastness. In this respect,
they approximately equal the performance of quinacridone pigments."

[Mythrill]

Originally Posted by Gigalot

"Perylene pigments exist in a wide range of hues, they provide red, bordeaux, violet,
brown and black shades. The pigments exhibit excellent solvent stability, good
to very good migration stability in plastics, fastness to overcoating in paints, high
chemical inertness, and superior thermal stability. Only the basic compound, the
dianhydride of tetracarboxylic acid, is not fast to alkali.
As a group, perylene pigments offer high tinctorial strength. They are frequently
found to be appreciably stronger than quinacridone pigments. Moreover,
perylene pigments provide excellent lightfastness and weatherfastness. In this respect,
they approximately equal the performance of quinacridone pigments."

I see what you mean, Giga, but dickblick.com was specifically talking about PR179 (Perylene Maroon) not being suitable for acrylics, even though we now make paint with this very pigment today.

Maybe the changes in Winsor & Newton's binder and acrylic resin somehow allowed it to be there?

[Gigalot]

there are no information about PR179 fastness in acrylic in organic chemistry book