HOW TO "SHRINK" AN OBJECT
You can shrink or reduce the size of an object
in all dimensions by using this special mold making and
An original model, a shrunken copy made from
1:1 mix, and another made from 1:3 mix
show how to "enlarge" an object using latex rubber
can also shrink an object in three dimensions by using
gelatin molding compound or alginate to cast a duplicate
of the object, and then allowing the water in the
compound to evaporate. As the water evaporates, the size
of the casting will decrease evenly. This is very much
like the "shrunken heads" you may have seen where
someone carves a head from a fresh apple, and then
leaves the apple to dry out, creating a distorted,
shrunken version of the head. Using gelatin molding
compound or alginate allows you to better control the
shrinkage, and allows you to "shrink" existing objects
instead of having to carve them anew each time.
is the complete procedure to make a shrunken copy of an
Make a mold of the object you want to shrink. Latex
rubber molds are easy to make and will allow you to make
a mold of an object with undercuts. You can also use
Gelatin Molding compound to make a very quick mold. The
"new" Gelatin Compound you use to make the casting will
not stick to the cured Gelatin Compound in the mold, but
the mold will probably be damaged or destroyed when you
remove the casting.
Use Gelatin Molding Compound as the casting material.
Mix the compound as follows, according to how much you
want the casting to shrink:
shrinkage factor times the original size of the object
is the approximate size of the gelatin casting after it
is allowed to shrink. For example, if your original
object is 4 inches tall, and you make a casting with
gelatin compound mixed 1:3 with water, when all the
water evaporates from the casting the shrunken gelatin
will be 4 inches x .55 or about 2.2 inches tall. The
more water you use to mix the gelatin compound, the more
your Gelatin casting will shrink, and the more it will
distort as it shrinks.
Pour the mixed gelatin compound into your mold, and let
it set. When the casting is firm, remove it from the
Set the casting on some paper towels and leave it in the
open to dry out. It may take 2-3 days to completely dry
out. If you want to speed the process, you can put the
casting in a microwave for 30 seconds or so. Watch the
gelatin, and as soon as it starts to steam, turn off the
oven. You can repeat this procedure over a period of a
few hours until the casting is mostly dry. Another
alternative is to put the casting in an oven turned on
very low (about 175º F) and leave it for a few hours.
The gelatin will shrink quite evenly in all dimensions,
and should make a good, but smaller, reproduction of
your original object.
castings that shrink a little bit (a 1:1 mix) will
generally be more accurate than those that shrink more.
Gelatin castings that shrink a lot (a 1:3 mix) may have
some distortions or warped areas.
your dried, shrunken casting is warped or distorted, it
is easy to fix:
spots can easily be carved down with a sharp knife, or
sanded with sandpaper.
spots or air pockets can be filled with wood putty,
clay, or spackle.
Once you have a good casting in the size you want, give
it a couple of coats of clear spray sealer such as
"Krylon" clear acrylic spray. Then you can make a rubber
mold of the shrunken casting and make as many
reproductions as you want, in the material of your
If you want an even smaller casting, you can repeat the
process as many times as you want - make a mold of the
shrunken casting, cast gelatin into the mold and allow
the casting to shrink, make another mold, and so on.
a PDF source list
Includes 26 suppliers of all mold making and
casting materials mentioned in ALL the demonstrations on
this web site, including silicone rubber, polyurethane
rubber, latex rubber, polyurethane plastic, epoxy resin,
polyester resin, molding clay, foam board, release
agents, pottery plaster, Hydrocal, metal powders, other
plastic resin fillers, and gelatin molding compound.
With company names, addresses, phone numbers, and web
sites. Downloads to your computer as a PDF file.