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mason stains (snail?)

updated wed 7 jun 06


earlk on mon 5 jun 06

On Mon, 2006-06-05 at 19:52 -0700, marianne kuiper milks wrote:
> I am trying to remember how to use mason stains,


I'm not normally one who jumps up and
down and yells "Search the archives !"
but in this case I think it is appropriate.

I did a Google on "Clayart stain" and
immediately got back a long list of
references. The first one I clicked took
me to which then gave me
another long list of references. Some of
these mention "watercolor" in their title.

So, if you really want to understand how
to use stains there's a wealth of info out
there already. Even some from the well
respected, but sadly deceased, Ababi;
Clayart's self proclaimed Glaze Addict.

I got so carried away reading these old
posts I almost forgot to respond to your

bothell, wa, usa

marianne kuiper milks on mon 5 jun 06

I am trying to remember how to use mason stains, since I lost the notes from a great tile-making class I took some time ago.
I have a variety of colors. I also have a dry-mix for a satin glaze.

I bisque at 06-04 and fire (gas) at ^4-6.
I use both a Sandard ^ 4-10 as well as Sandy Buff, which is ^4-6 The last one I have not yet fired: trying it out.

The question:\How can I mix it...with water? Do I add a clay-ish material?
Can I mix it directly with the glaze?
Can I brush the mix or water stain on greenware, or must I bisque first?
Can the colors be mixed to obtain another color?

I asked Lili, who suggested that I contact Clayart, Snail in particular.

I have a bunch of pieces I would like to use the water-colorish effect on thsat I liked so miuch in the class I took. I also have to match a series of tiles from a water-wall.

Thanks, guys.


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Snail Scott on tue 6 jun 06

At 07:52 PM 6/5/2006 -0700, you wrote:
>I am trying to remember how to use mason stains...
> The question:\How can I mix it...with water? Do I add a clay-ish material?

You can use them as a wipe or a surface stain
this way, but since they are refractory, they
won't fuse to the clay unless they are applied
very thinly and over a fairly vitrified body.
This way, the clay itself helps melt the stain
just enough to stick. That's why stains by
themselves need to be very thin. For more
versatility, you can add a flux to the stain,
to allow it to stick without relying on the
nature of the clay. This can be a frit (3134 is
a common one that works), or a lower-temperature
feldspar like nepheline syenite, or even borax.

Adding clay-ish materials help keep the stain
suspended in the water and also make the stain
less concentrated, which helps you to apply a
more even coating. It can subdue/tint the color
a bit, depending on the amount of clay. Another
role for clay is that it makes the surface less
dusty when it dries, and it will be less likely
to smudge when handled during kiln loading and

A classic two-for-one for this purpose is to add
gerstley borate, since it aids in suspension AND
acts as a flux. I haven't tried it with any of
the gerstley subsitiutes. (Anyone else?) Based
on other usages, though, most of the substitutes
are quite suitable as fluxes but are less useful
for suspension. A tiny amount of bentonite will
do for suspension, though, or a larger amount of

Note that if you use a lot of clay, what you've
done is created an engobe, so you may choose to
approach it with that in mind. Lots of clay will
make a mix with a high shrinkage, so using some
calcined clay instead will reduce shrinkage.
The thinner the application, the less the high
shrinkage matters, AND, the damper the clay the
less it matters. So, for leather-hard clay, you
can get away with a lot. With greenware, you
can get away with some, and for over bisque, it
needs to be carefully considered.

So, decide on your intent: thin washes? opaque
coatings of color? Thick built-up texture? The
thicker it is, the more clay you'll need, and the
more the compatibility of shrinkages matters.

Think about engobes. As a category, they include
almost all the range that lies (recipe-wise) in
between washes and glaze. A huge range of potential
effects, and since they are not glassy, they are
very forgiving of off-the-cuff formulation. Just
try some stuff; experiment!

> Can I mix it directly with the glaze?

Yes, keeping in mind that stains are refractory,
so a large amount of stain will tend to raise the
melting point of a glaze. Adding extra frit can
offset this, though such tinkering will usually
alter the final look of the glaze. Go ahead and
do some tests.

> Can I brush the mix or water stain on greenware, or must I bisque first?

Washes on greenware re-dampen the surface of the
clay, leading to two issues. First, some clays do
not tolerate being heavily re-wetted and may crack
from the unequal re-expansion of the damp areas.
Forsuch clays, apply only lightly or try another
clay. The thinner the clay, the more vulnerable it
will be. Leather-hard clay actually absorbs less
water, so applying a stain during this stage may
be less damaging. It will tend to absorb less color,
too, though. Second: If you plan to sponge off the
color to get an 'antique' effect or to enhance
texture, green clay may smear too easily and muddy
the effect, though it may actually be what you want.

Bisqued clay will not be affected by these issues.
Color can be sponged off vigorously without affecting
the clay form at all. You can apply repeated layers
without oversaturation. Color does tend to penetrate
more deeply into the bisque, which may be good or
bad, depending on your intent. It can be hard to
wipe enough color off for a high-contrast textured
effect if your clay is very 'open' and coarse, so a
tighter, finer clay may be more suitable if this is
your intent.

> Can the colors be mixed to obtain another color?

Yes. (Finally, an unambiguous answer!) Most Mason
stains do not react chemically with one another,
so they can be mixed much like paint. That's why
commercial underglazes (just a form of engobe) and
those 'underglaze watercolors' (another form) can
be mixed like paint, too: their colorants are Mason

(By the way, Mason is a brand name. There are other
brands, but 'mason' has become almost generic in
conversation, like kleenex or thermos. So, when
people say "mason stains", they aren't always
referring to that manufacturer, but the general
principles still apply.)

> I have a bunch of pieces I would like to use the water-colorish effect...

For this, use a smooth white clay, or coat your clay
with a smooth white slip or underglaze. (You can use
a colored clay but it will be like painting on colored
paper.) If you bisque first, I would dunk the work in
water before painting, to reduce the absorbency of
the bisque. This will allow for longer, more flowing
strokes. If you work on greenware, don't dunk in
water. Greenware is less absorbent, so you may get OK
brushwork anyway. A lot depends on your clay, which
I have not used, so a few experiments may be in order
if these pieces are very labor intensive. You can
vary the bisque temperatuere to affect absorbency,
too. Do a few test tiles, bisqued and not, using
varying amounts of flux. Try some with a little clay
as well, and some CMC gum. Adding glycerine can also
improve flow.

>I also have to match a series of tiles from a water-wall...

Matching is a tough assignment! It may be better to
coordinate than to try a true match, but again, do
some tests.

Some masons stains don't like certain glazes, so
if you are planning to put a clear glaze over your
painting, test the glaze over them before doing the
real projects. If some colors fade or change, try a
different glaze formula, or other stains.

You said you fire to ^4-6 in a gas kiln. Some stains
are vulnerable to a reducing atmosphere, so be alert
for this. To avoid the issue, simply fire in oxidation.
Just because it's a gas kiln doesn't mean you have
to fire in reduction! If you are sharing the kiln,
and can't insist on oxidation, be aware that the
pinks, reds, purples, and oranges tend to be the most
affected. Greens, blues, browns, tawny colors and
blacks do OK. But, these are the colors you can get
without stain from plain oxides, so if you can, get
the most from your expensive stains and try for

Testing is the best prevention for bad surprises.

Good luck!