DESCRIPTION: PMC724 is an exceptional jewelry molding
rubber for wax injection.
It pours easily, and cures
(without heat) to a tough durable rubber that is easy to cut, and yet soft
enough to allow removal of waxes without breakage. Part A is a brown liquid
and Part B is a white syrup. Part A
& B must be proportioned, by weight, in a 10A to 100B ratio using a scale,
and then thoroughly mixed. After
mixing, PMC724 will remain pourable for at least 20 minutes. Molds can be used the next day. Physical
properties (after 72 h cure at 72°F):
Specific
Volume, cubic in./lb. 20
Hardness 40
A
Ultimate
Tensile Strength 600 psi
Elongation
at break 700
%
Linear
Shrinkage Negligible
MODEL PREPARATION: Normally, PMC724 can be poured against the
glass/aluminum frame and the ring pattern without fear of adhesion. But where
there is a question of compatibility or adhesion, a test cure should be made to
insure complete curing and good release.
In some cases, #200 EaseRelease has been used to assist the
release.
MIXING AND CURING: Part B should be stirred before use as it
may settle from storage. Both parts
tend to absorb atmospheric moisture, and should be kept away from steam and
water. During storage, the lids should
be kept tightly sealed and protected
from humidity.
The mixing ratio of 10 parts A to 100 parts B by weight is critical. Proportioning errors will affect the
physical properties of the cured rubber.
Part B should be weighed into a clean metal, glass or plastic container,
then the appropriate amount of part A can be weighed into the same
container. Do not use wood or paper
mixing tools as they can introduce moisture.
While mixing, scrape down the sides of the
mixing container several times to insure thorough mixing of both
components. Vacuum degassing will help
to provide void-free molds but is usually not necessary. Allow to cure overnight (16 hours minimum)
at room temperature of 72°F before demolding.
Ultimate properties are reached in 3 days. Curing in a warm location, up to 150°F will greatly
accelerate the curing speed.
STORAGE: PMC724 will remain usable for at least six
months from date of manufacture in unopened containers stored in a cool, dry
place. Cured molds will slowly soften
with age due to absorption of humidity.
The best way to store cured rubber is in tightly sealed plastic bags (to
seal out moisture) and place in a cool, dry, dark place. With proper care molds should not soften
appreciably for 4 or 5 years.
PMC724 is available in the following
sizes:
Pint
kit 1 lb
Gallon
kit 9.9 lb
5
Gallon kit 49 lb
55
Gallon Kit
Warning:
Uncured product may cause respiratory or skin irritation with possible
sensitization. Use only with adequate ventilation. If skin contact occurs, wash
thoroughly with soap and water. In case of eye contact, flood with water and
call a physician. Use of gloves and face shield is recommended. This product should not be used near food or
where prolonged skin contact may occur.
Disclaimer: This information is based on sources that we
believe to be accurate. It is offered in good faith, but without guarantee,
since conditions of use are beyond control. All risk of use are assumed by the user.
