Making a mold of decorative concrete edging is a cost-effective way to line your garden or yard. You can buy a single piece of edging that you like, make a mold of it and then fashion as many additional pieces as you want. This mold will be made of rubber, which will be peeled off the rigid concrete as one of the final steps. You must also build a support shell to help the rubber mold to keep its shape.
Items you will need
- Edging piece
- Acrylic enamel spray
- Rubber molding latex
- Cheap paintbrushes
- Plastic wrap
- Hair dryer (optional)
- Plaster bandages
- Bowl of warm water
- Petroleum jelly
- Duct tape
Place the section of decorative concrete edging that you want to mold onto a horizontal working surface.
Spray the edging with three coats of acrylic enamel spray to seal the surface. Allow each coat to dry completely.
Brush a layer of rubber molding latex onto the top and sides of the edging with a cheap paintbrush. Wrap the brush in plastic wrap to prevent the rubber from drying in the bristles, which will destroy the brush.
Allow the latex rubber on the edging to dry. This process can be sped up with a hair dryer.
Apply 10 additional layers of rubber, allowing each to dry before adding the next.
Cut several rolls of gauze into five-inch pieces.
Apply an additional layer of rubber onto the mold, then press overlapping pieces of gauze into the wet rubber. Brush more rubber into the gauze, saturating it and encapsulating the gauze. Allow the rubber to dry.
Apply four additional layers of gauze and rubber, allowing each layer to dry.
Brush on five final layers of rubber, allowing each to dry.
Draw a line down the middle of the edging with a marker, dividing it into equal right and left halves.
Tear several rolls of plaster bandages into six-inch strips.
Dip the strips one at a time into warm water, then smooth them onto one half of the mold. Build up six full layers of overlapping bandages, then allow them to dry. This is one half of a support shell that will help the flexible rubber mold to hold its shape.
Brush a coat of petroleum jelly along the middle edge of the bandages, following the marker line.
Apply six layers of plaster bandages to the other half of the mold, overlapping the edge of the first by one inch. The petroleum jelly will prevent the two halves from sticking together. Allow the bandages to dry.
Remove the two halves of the shell and peel the rubber mold off the concrete edging.
Reassemble the shell around the mold, wrapping both ends with duct tape to hold it together. The mold is now ready to have fresh concrete poured into it.
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- "The Prop Builder's Molding & Casting Handbook"; Thurston James; 1989
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