Page 37 - 4th edition Nayi Udaan

9.Label the clear cups 1, 2, 4,
Procedure:
This experiment uses hot liquids, so an adult's
help will be needed throughout.
1.Using the masking tape and pen, label the
four mugs: 1, 2, 4, and 8.
2.Use the measuring spoon to add 1 teaspoon
(tsp.) of white vinegar to the mug labeled "1," 2
tsp, to the mug labeled "2," 4 tsp. to the mug
labeled "4," and 8 tsp. to the mug labeled "8."
3.Heat 4 cups of milk in a large measuring cup
on the Flame..
a.The exact amount of time needed will
depend on your microwave. Start by warming
the milk for five minutes. Avoid scalding
(burning) the milk.
b.Have an adult check the milk with a ther-
mometer to make sure it is at least 49°C
(120°F).
5.Carefully pour 1 cup of hot milk in to each of
the four mugs with vinegar in them. What do
you see happening in each mug? In at least one
of the mugs you should see that the milk has
separated into white crumps (called curds).
6.Make sure to pour the milk in to all four of
the mugs at the same time so that the milk is
the same temperature across all four vinegar
amounts. Mix each mug of hot milk and vine-
gar slowly with a spoon for a few seconds. That
will help make sure the vinegar reacts with as
much of the milk as possible.
7.Meanwhile, take one of the cotton-cloth
squares and attach it with a rubber band
to the top of one of the clear cups so that
it completely covers the cup's opening.
Make sure the cloth hangs down a bit
inside the cup so that you have room Gurvinder Kaur
to pour liquid in. Vikas Bharti public
8.Repeat this step with the other school,North West A
three clear cups.
and 8 with the tape and pen.
10.Once the milk and vinegar
mixture has cooled a bit, care-
fully pour the mixture from
mug "1" into the cotton cloth
sieve on cup "1." If there are
any curds, they will collect in
the cloth sieve. The leftover
liquid will filter into the clear
cup. Figure below shows what the setup looks
like. Where do you think the casein is, in the
liquid in the cup or the curds in the sieve?
11. Over a sink, carefully remove the rubber
band sieve on cup "1." With your hands,
squeeze all the extra liquid out of the curds.
Scrape the curds off of the cloth and knead
them together, as you would bread dough, into
a ball. This is your casein plastic. Before it
dries, the ball of dough will look similar to
Figure below.
Ideas for Fun with Your Casein Plastic
Try making beads, ornaments, or figurines out
of your casein plastic. You should do the mold-
ing and coloring steps (except for paint and/or
marker) within the first hour of making the
plastic or it will start drying out.
Shaping the plastic:
a.Knead the dough well before shaping it.
b.Molds and cookie cutters work well on the
wet casein plastic.
c.You can also sculpt the wet casein plastic
into figures, but it takes a bit more patience.
2.Coloring the plastic:
a.Food coloring, glitter, or other decorative
bits can be added to the wet casein plastic
dough. The beads in Figure 3 above were made
from casein plastic dough that had yellow food
coloring and multicolored glitter kneaded
into it.
b.Dried casein plastic can be painted
or colored on with markers. The
smiley face in Figure 3 is on uncolored
casein plastic and was drawn on
using a black permanent marker.
3.Hardening the plastic: Casein
plastic will be hard once it has
dried.
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