Preparing an Ingot Mold

Q: I tried to pour a gold ingot in my new cast iron ingot mold, but the metal is stuck and won’t come out. I sprayed it with WD-40 first—what’s the problem?

Mounting Vibrating Laps and Centrifugal Casting Machines

Q: I need to install a vibrating lap in a fixed location, so it won’t walk all over the place. Short of bolting it to the concrete floor, any ideas on how to stabilize the base?

Labeling Rubber Molds

Q: I make a lot of rubber molds, and I’d like to mark them for identification, but there doesn’t seem to be anything I can write on the outside of them with that is permanent. Any ideas?

Can Old Vulcanizable Mold Rubber Be Used?

Q: I’ve got some Castaldo Ready-Cut Mold Rubber that’s been sitting around for more than 5 years. Can this still be used, or has it lost its ability to vulcanize?

Cast Concrete Sculpture

Q: How do you go about making concrete sculpture like the kind you can buy for your garden?

Cast Marble

Q: How does one go about making sculpture in “cast marble” or “bonded marble?”

Alternative Casting Materials

Q: I would like to cast something into molds (besides plaster of Paris) that would end up looking like white marble. Should I use polyester resin or what?

Casting Sterling

Q: How hot should the oven get when burning out jewelry investments? How hot should the mold be when you cast sterling silver? Why have my castings been coming out black and pitted, with little pinholes?

Clays for Sculpture

Q: I want to try doing sculpture. What kind of clay should I use?

Concrete—How to Use It?

Q: I am casting simple forms in concrete, mostly using holes in the ground for molds, and I’m looking for ways to generate different interesting forms and surfaces. Any ideas?

Concrete Textures

Q: I’m interested in experimenting with concrete to get different surface effects than the usual boring cast concrete look. Any suggestions?

Direct Concrete without Casting

Q: How could I make sculpture directly in concrete, without having to go through modeling a form, making a mold, and casting the concrete?

Forton MG Plaster

Q: What is this Forton MG plaster you mentioned, and where do you get it?

Cheapest Mold Material for Clay Models

Q: I’m making models in clay that have lots of undercuts, and would like to take molds of them so I can make permanent sculptures in plaster or polyester resin. What is the cheapest thing I can use that won’t tear up the originals too badly?

Mosaic-surfaced Stepping Stones

Q: I want to make some concrete stepping stones with a mosaic surface. What kind of mold, concrete/aggregate mix, and setting technique should I use?

Making Sculpture in Papier Mache

Q: How do you make the paste for papier mache? Is it just flour and water? What can you build it on besides balloons?

Smooth Surfaces in Plastiline Clay

Q: I want to make a small sculpture in plastiline (oil-based) clay. I want to create extremely smooth flowing curves, with no tooling marks. What is the best way to achieve this result?

Air Bubbles in Plaster

Q: When I cast plaster into a rubber mold, how can I prevent bubbles from sticking to the mould and making holes in the casting?

Making Clay Pipes

Q: I want to make some clay pipes for smoking. What clays are best for resisting heat? How do you get that long tunnel to go down the stem? And how do you sculpt on them without mashing them up?


Q: Where can I find information on life-casting? What are the best materials to use? What about plaster bandages, do they work?

Making Stamps for Ceramic

Q: Does anyone know how to make stamps for ceramic?

Manganese Bronze Problems

Q: I’m melting manganese bronze and it makes a lot of smoke when I pour it into my plaster investment molds. Then the castings seem to come out porous, black and pitted. What am I doing wrong?

Plaster Modeling

Q: Can I model directly in plaster of Paris, or do I have to make a mold?

Molding My Own Face

Q: I want to make a mold of my face, but I don’t know how. Do you use plaster?

Finishing Silver Castings

Q: What steps should I take in order to get a good polish on sterling silver castings?

Vacuum Casting

Q: What is meant by “vacuum casting”? Does it happen in a vacuum?

Dies for Coins and Medals

Q: How are the dies for coins and medals made? Is this something a jeweler can do without a lot of expensive equipment? Can etching techniques be used?

Polishing Sterling Silver Castings

Q: What steps should I take in order to get a good polish on sterling silver castings?

Alloying Gold

Q: I’ve got a piece made of 22 karat gold, and I want to cast some 14 karat gold. Can I add something to it to make the lower-karat alloy, and if so, what, and how much?

The Rubber FAQ—Flexible Mold Materials Compared

Christopher Pardell explains why silicone rubber comes closest to the ideal, and where other types fall short. This article compares the following materials: latex, gelatins, alginates, urethanes, neoprene, vinyls, polysulfides, and silicones.

The PVC FAQ—Using Hot Melt Vinyls

Evan Hughes, with a somewhat contrary view, explains how this material can be an economical substitute for expensive rubber compounds in some applications. This article covers the following topics: using hot-melt vinyl for making flexible molds, melting it, the electric pot, pouring, hazards, and limitations.

The Plaster FAQ—Working With Plaster

Christopher Pardell gives detailed instructions on how to mix and use this versatile material, with advice on plaster mold-making, casting, and direct tooling. The article covers the following topics: plaster defined, its qualities, various uses, flexible molds, different types, modifications, investment, storage, hazards, water bubbles, air bubbles, tooling, mixing containers, mixers, industrial techniques, mixing by hand, influencing set time, reinforcements, use in sculpture, mold casings, fractioning the batch, cautionary notes, waste molds, separating sections, using shellac, adding on, fixing holes, slosh-casting, handling large molds, tempering and drying, tools, and last tips.

The Latex and Urethane FAQ—Casting Positive Forms in Latex and Urethane

Christopher Pardell goes over the steps taken by FX artists to create flexible objects which can be painted. This article covers the following topics: uses of rubber parts, plaster molds, thin latex castings, painting latex, foam latex, latex and urethane foam, self-skinning urethane foam, painting urethane rubber, urethane’s characteristics, and safety notes.

The Urethane Rubber FAQ—Making Molds with Urethane Rubber

Dan Spector steps up to the plate, and makes the case for urethane elastomers in sculptural moldmaking. This article covers the following topics: advantages of urethanes; heat and distortion, sheet molds, including fibers and foam; adding rubber to rubber; limitations and drawbacks, box molds, and poured mold variations.

The Silicone Rubber FAQ—Using Silicone Rubber for Mold-making

Christopher Pardell describes his technique for mold-making with this space-age material. This article covers the following topics: silicone rubber for mold-making, additives, sealing the model, mold seams, de-airing, first coats, fill coats, gloss coat, reinforcements, mold casings, casting polyester resin, slab molds, another poured technique, and cup molds.

The Resin FAQ—Casting Resins into Molds

Christopher Pardell covers the various types of resin commonly used by sculptors for filling molds, including polyester, urethane, and epoxy. This article covers the following topics: casting vs. layup, suitable molds, types of resin, polyester resin, polyester’s drawbacks and hazards, epoxies, urethanes, clear castings, shrinkage flaws, heat effects, shrinkage cracks, achieving larger castings, slowing polymerization, filling resin, various fillers, air bubbles, mixing, agitation and vacuum, and pressure casting.

The Concrete FAQ—Concrete Casting

Dan Spector reveals the secrets for successful concrete castings using this versatile and inexpensive material. This article covers the following topics: concrete defined, Portland cement, aggregate mix, cement proportions, water content, rock size and molds, drypacking, mixing, additives and special mixes, use of rebar, surfactants and vibrators, hardening and curing, tinting and washing, decorative treatments, staining and painting.

The Wax FAQ—Sculpting in Wax

Andrew Werby covers the use of wax in sculpture, including the types used, direct construction techniques, casting, welding and smoothing. This article covers the following topics: sculpting waxes, carving wax, casting slabs, melting, handworking and tools, lost wax, armatures and addtitions.