3 to 4 layers is all that is necessary to make a strong, durable production mold for
casting wax, gypsum, concrete or resins (urethane, polyester, etc.) and because Rebound
25 is a platinum silicone, it will last for many years in your mold library.
Applications include reproducing sculpture, architectural restoration, making candle
molds, and more.
Secure original model to baseboard with hot melt
glue gun to prevent movement during the mold making process.
Secure model in center of working board.
Dispense equal amounts of Rebound 25® A + B into mixing container. Mix for 3 minutes.
Make sure you scrape the sides and bottom of container many times. Eliminate all color streaks.
Brush a very thin layer onto model. Work rubber into fine detail.
Cover the entire model and create a 3 inch
(7.62 cm) flange in all directions around model.
Allow rubber to cure 60 minutes until tacky.
Ready! Rubber should be sticky to the touch, does not come off onto your glove. If rubber is still wet, do not apply the next layer.
2nd Layer - After the 1st layer is tacky. Mix and apply another layer of rubber.
After model and board are covered, let rubber cure for 60 minutes until tacky.
Create a Cut Seam. Measure and mix a small amount
of Rebound® 25 A+B. Add 4 drops of Thi-Vex
thickener to every 1 oz. of mixed Rebound® 25.
The thickened rubber will hold a vertical surface.
Apply thickened rubber at the top of the model and
work downward. Bring cut seam all the way out to the end of the flange.
Use thickened rubber to fill undercuts.
3rd Layer - Mix and apply another small batch of
rubber. After model and board are covered,
let rubber cure 60 minutes until tacky.
Mix up a small batch of thickened rubber (same as steps 11&12)
Further build up “cut seam” with thicker rubber.
Use thickened rubber to fill in undercuts and reduce sharp angles.
4th Layer - Mix and apply a final layer of rubber to model and baseboard.
Let all layers cure at least 6 hours at room
temperature ( 72˚F/22˚C) before applying the Plasti-Paste support shell.
Use a razor knife to trim the rubber.
Sharp clean edges will help the rubber mold register with the support shell.
Examine the model to determine the best place for the parting line.
Draw a line with a marker along the models’ high points, dividing it into two halves.
Apply modeling clay along the parting line to create a
“parting shim” which will separate the support shell sections.
Smooth the surface and trim excess clay. Clay parting shim should be 2” - 3” high.
Cover 1/2 of the clay shim with thin gauge aluminum
The foil forms a barrier between the clay and Plasti-Paste® shell which will aid in separating the two segments later on.
Apply a liberal coat of Sonite Wax® to the entire surface of the baseboard.
Let the Sonite Wax® dry for 10
minutes and apply a second coat.
WARNING: Plasti-Paste® sticks to everything!
Measure and mix Plasti-Paste®, 1A to 3B. Scrape sides and bottom of container to ensure a thorough mix.
Apply Plasti-Paste® over the surface of model, platform and shim, to 3/8 inch (.95 cm) thick.
Allow the Pasti-Paste® to cure for at least 90 minutes at room temperature (72º F / 22º C). Once cured, fold the
aluminum foil out of the way towards the cured
Plasti-Paste®. Remove the clay shim.
Apply a liberal coat of Sonite Wax® to the surface of the aluminum foil and baseboard.
Let the Sonite Wax® dry for 10 minutes and apply a second coat.
Measure Plasti-Paste®, 1A to 3B and mix thoroughly.
Apply Plasti-Paste®, over the surface of model, platform
and shim to approximatly 3/8 inch (.95 cm) thick.
Allow the shell to cure for at least 90 minutes at room temperature (72ºF/22ºC).
When cured, remove excess aluminum foil. Use a hammer and chisel or screwdriver to seperate the shell sections. Slowly pry the support shell segments apart and release from baseboard.
Remove the sections to expose the rubber mold.
Use a razor knife to carefully cut the rubber seam
from bottom to top. WARNING: RAZOR KNIFE IS SHARP!
Gently remove the original model from the rubber mold.
Align the cut seam and secure into the Plasti-Paste® support shell.
The cut seam should almost disappear.
Use rubber bands to secure support shell segments together. The mold is now ready for casting.
Place the mold upside down in a bucket for
support and stability.
Level the mold for best results.
Measure equal amounts of A & B Smooth Cast® 300.
thoroughly, make sure to scrape the sides and bottom of container several times.
Slowly pour the liquid mixture into the mold. Rotate
the mold during the pour to eliminate air bubble
Allow the resin to cure for 20 minutes.
CAUTION: Smooth Cast® 300 becomes VERY HOT!
Let cool before handling.
Remove the mold from the bucket. Remove the
Plaste-Paste® shell. Carefully remove the casting from the rubber mold.
The finished casting is an exact duplicate of the original.