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Pigments are like tiny, inert, colored rocks
Because pigments do not react chemically with
anything, they tend to be very light fast, resisting fading
in sunlight
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Pigments can become “paint” when
suspended in a binder such gum arabic for watercolor paint or
acrylic medium for acrylic paint
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Pigments are
also an excellent material to color paper pulp
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When pigment
is used to color paper pulp, however, it is
suspended in water with no adhesive-like binder as in paint
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Pigments are very easy to use and they mix
together well in order to create subtly colored pulps
Primary pigments, such as yellow and blue, can be
combined to create secondary colors, like green, before OR
after the pigment is added to the pulp
For
example, yellow pulp can be mixed with red pulp to create
orange pulp
Several pigments or colored pulps
can be mixed together to create taupe or mauve
AN IN-DEPTH EXPLANATION OF THE PRINCIPLES INVOLVED IN
COLORING WITH PIGMENT: Pigment
sticks to paper pulp through a “+” and “-”
attraction, a little like a magnet
The cellulose plant fiber (pulp) is
anionic; which means that it has a negative charge which
increases from the pounding or beating of the fiber
during pulp preparation in the hollander beater
Dry,
unbeaten, fiber has very little or no charge
As the fiber is
beaten into a pulp, the “-” charge increases
Pigments
have little attraction to the pulp, so a material which
has a “+” or positive charge must be added
Retention
agent is such a material, and its only purpose is to
provide the “+” charge
Internal Sizing is a mild
waterproofing agent which also happens to be cationic; it has
a positive “+” charge
Consequently, Internal Sizing adds
both waterproofing properties AND retention
properties
The positive charge of the fiber depends on how
much the fiber has been beaten in the pulping
process, the longer it is beaten the greater the charge
Cationic materials (with a “+” positive charge) add to
the charge
If you pour in too much retention agent,chowever,
you can add too much “+” charge, the poles on
the little magnets will reverse, and all the pigment will
instantly come off the pulp
If this happens, just rinse
the pulp, washing away the pigment and excess retention
agent
Then add more pigment
You may not need
anymore retention agent as there may still be enough on the
fiber
If you feel like you need more, just add a
tiny amount and dilute it a lot before adding it
DIRECTIONS FOR COLORING PULP WITH SIZING AND RETENTION AGENT:
At Twinrocker, we color with
pigments by first sizing pulp made from 3 pounds of dry fiber
(1 beater load which is one 5 ga1
pail of
ready-to-use pulp) with 50 ml
or 5 tbsp
of our Internal
Sizing
We dilute the measured sizing in plenty of
water (about a quart) and slowly add it to the pulp while
stirring to mix it in evenly
This sizes the pulp and
adds some “+” charge
We then add the pigment to the
pulp
A tiny amount of red will create a pink pulp,
more red, a more intense color
The liquid pigments are very
concentrated, so begin by adding just a little
If
you want an intense color, add a little pigment and mix it
into the pulp well before you add more
Gradually
build the intensity of the color
If you find you’ve added
too much pigment for the color you want, just add
more white pulp to make the color more pastel
After stirring
the pigment into the pulp thoroughly, it should
automatically stick to the pulp, and the water should be
clear or almost so
If you still have pigment in the
water after you have stirred the pulp thoroughly by hand, the
pulp is saturated
The pigment has attached to
most of the bonding sites on the fiber, and little if any
more pigment will stick to the pulp
It is that simple
No
rinsing is needed after coloring
Using this method, the
pigment normally attaches to the pulp quite well
without the addition of any retention agent
However, if the
pulp has not been beaten very much and does not
have a strong “-” charge, we then add a little, very
dilute liquid retention agent (perhaps a tsp
of in a quart of
water)
We add it slowly while stirring so that the “+”
charge is mixed in the pulp evenly and stop adding it
when the color begins to attach to the pulp
If the color is
too intense, you can lighten it or make it more
pastel by adding white pulp
A couple of our customers, who
are not pulping cotton linters in a hollander
beater, but in a mixer or blender instead, color their pulp
using retention agent in a slightly different manner
They dilute the pigment they want to use with water, then add
a little retention agent to that pigment/water
mixture, and then add that mixture to the pulp
If you are
having trouble coloring fiber that has not been beaten
in a hollander, try using our dry, powdered retention agent
as it is stronger than the liquid material
We have
found that the dry material tends to “overcharge” fiber
prepared in a hollander, however
COLORING PAPER PULP WITH PIGMENTS IS EASY AND A LOT OF FUN
This is a fairly detailed
explanation of how pigments stick to paper pulp, but I could
have said, “It’s magic
” That’s how spontaneous
and easy it is to do
Mixing colored pulps together to create
art work is as easy as mixing colored paints
together
If you should have a problem, just give us a call
at Twinrocker, and we’ll be happy to help you