Forms of Metal Clay: Lump, Powder, Slip, Syringe, and Paper Type Clay
Metal Clay = The Magic of Modern-Day Alchemy!
Metal clay is an amazing malleable form of metal that lets you create jewelry, small sculptures and other objets d'art in a range of different metals — pure silver (.999 fine silver), sterling silver (.925 silver), .900 silver (AKA coin silver), 22K gold, copper, bronze, rose bronze, white bronze, brass, steel, pearl grey steel and more — without a lot of costly tools, and even if you don't have any prior metalsmithing or jewelry making experience.
Metal clay is made of microscopic particles of metal mixed with an organic binder and water to create a clay-like material that can be molded, folded, cut, extruded, embossed, rolled, sanded, filed, drilled, carved, etc., to form nearly any shape, design or texture your mind can conceive. After it has dried, it is fired at high temperatures in a kiln (in a container of activated carbon for formulas that contain base metal), with a torch, or over a woodburning or gas stove. The binder burns away and any remaining moisture evaporates, leaving behind just the metal.
Fine silver metal clay is available in all five forms: lump, powder, slip (AKA paste), syringe, and paper-thin sheets (PMC Sheet and Art Clay Silver Paper Type). Gold metal clay is available only from PMC (lump clay only) and Art Clay (both lump clay and paste). An increasing number of brands now offer sterling silver (.925) and enriched sterling (.950 and .960) lump clay, and powdered enriched sterling is now available as well from Aussie Metal Clays. A wide range of base metal clay formulas is available as lump clay or powder, but can be mixed with water to form slip. As of this writing, Prometheus is the only base metal clay available as syringe; however, it is possible to hydrate lump clay to make it moist and soft enough to be extruded through a syringe, and fresh clay can be extruded into strands through an extruder. There are more and more flexible, "flex clay" formulas that can be rolled out to 1 or 2 cards thick to create sheets that remain somewhat flexible after they have dried, and most non-flexible lump metal clay can be mixed very thoroughly with a small amount of glycerin to create flexible sheets of clay that behave similarly to silver PMC Sheet and Art Clay Silver Paper Type.
This article will focus on the properties and applications of each of the five forms of metal clay.
Lump clay is the basic and, arguably, the most versatile metal clay form. Because it contains the highest proportion of metal to binder and water, it also is the strongest form of metal clay. Here are some of the many ways in which it can be used:
- It can be shaped or sculpted by hand.
- It can be rolled out with a roller (e.g., a piece of PVC pipe) and cut into the desired shape with aspic cutters, cookie cutters, clay cutters, clay punches, brass tubing, a tissue blade or clay blade, a needle tool, a craft knife, a straw, the side of a playing card, or nearly any other cutting implement you can come up with.
- It can be textured easily by pressing a textured object into it (anything from a piece of lace to a toothpaste cap to a custom photopolymer plate texture), or by pressing it into a mold, rolling it out on a texture plate or carving it when leather-hard (mostly but not completely dry). There are dozens of ways to add texture to lump metal clay!
- It can be rolled into snakes (AKA coils) or balls.
- It can be thinned with water to make slip in a variety of consistencies, from thin slip to very thick paste.
Metal Clay Powder
The newest form of metal clay
In recent years metal clay in dry powder form has become extremely popular and more and more manufacturers are offering them. Hadar Jacobson offered the first metal clay powder in bronze and copper in her line of Hadar's Clay, which has since been expanded to include a wide range of base metal clay types. Other major manufacturers of metal clay powder include Goldie Clay, which also offers a wide range of base metal clay powder types including the extremely popular Goldie Bronze; Prometheus bronze and copper clay; Metal Mania Metal Clay, which offers a wide range of base metal clay formulas including brass and nickel; NobleClays, which makes silver, copper and bronze metal clay formulas in both lump and powder forms; Zab's Bronzes in a range of colors; and Aussie Metal Clay in a range of base metal formulas and colors in a flexible formula optimized for use when dry with the Silhouette CAMEO electronic cutting machine.
Powdered metal clay is convenient and versatile because it can be mixed with distilled water as needed to create lump clay, slip or paste in whatever quantity is desired. On the other hand, it can be tricky to mix to exactly the right consistency. The manufacturers provides mixing instructions for preparing their brands of powdered metal clay. Hadar Jacobson also has created a very helpful video for mixing Hadar's Clay powder into lump clay.
Video Demonstration and Instructions for Mixing Metal Clay Powder Into Lump Clay
Metal Clay Slip or Paste
Metal clay slip or paste is lump clay that has been thinned down to the consistency of a thick, viscous liquid or an even thicker paste. Its most common use is as a sort of "metal glue" to attach metal clay components together. Not all brands and versions of metal clay come in slip or paste form, but you can easily make your own by mashing drops of water (preferably distilled water) a few drops at a time into a piece of lump clay with a palette knife. You can mix the slip directly in a slip jar or container (a very small jar or other container with a tight-fitting lid in which you will store the slip), but I find it much faster and easier to mix my slip on a piece of glass and then scrape it into a slip jar. Here are some the ways in which metal clay slip or paste can be used:
- It can be painted on leaves in many thin layers to create metal leaves (the organic leaf burns off in the kiln).
- It can be used as "glue" to join metal clay pieces together before firing, or to attach elements (like metal clay balls) to unfired metal clay.
- It can be used to fill in very fine cracks in unfired clay.
- It can be painted on thickly with a brush or palette knife to create stucco-like or other textures (as you might do with cake frosting).
- It can be used to apply dimensional designs or patterns using the "slip trailing" technique, in which a brush dipped in slip is touched briefly to a dried metal clay component and then lifted up slightly and gently pulled horizontally to create a thin "thread" of slip that is allowed to trail down onto the component in a thin line. The design is created with a series of short, adjacent "slip trails" and then built up in successive layers to create the desired height or dimensionality.
For more detailed information and instructions for this technique, read the chapter by Terry Kovalcik in the excellent book, PMC Technic.
- Art Clay makes a special Overlay Silver Paste (OSP) for decorating porcelain, ceramic and glass with silver accents, and a fantastic Oil Paste product for making very secure attachments or repairs to fine silver (including fired silver metal clay).
- Thick metal clay paste can be mixed with 100% pure essential lavender oil or another pure essential oil or, ideally, with Sherri Haab PasteMaker to create a homemade oil paste that creates very strong attachments between pieces of metal clay. Oil paste made from silver clay and Sherri Haab Pastemaker can be used to join leather-hard, bone-dry or fired silver clay components, including making repairs to fired pieces, and to attach fine or sterling silver findings, wire or sheet metal. Oil paste made from bronze or copper clay and Sherri Haab PasteMaker can be used bronze or copper paste can be used to join moist, leather-hard or bone dry bronze or copper clay components. Learn how to make metal clay oil paste and how and when to use it.
Syringe clay's consistency is midway between that of lump clay and paste clay. It comes in its own non-refillable syringe with separate tips that can be interchanged. It can be used to attach or repair metal clay components, or to embellish them (similarly to embellishing a frosted cake with an icing-filled cake decorating syringe).
The tip of an opened clay syringe must always be submerged in water when not actively in use. During a work session, you can stand the syringe in your water jar with the point submerged, or in a jar with a soaking wet sponge cut to fit inside the bottom of the jar so that the tip of the syringe is pressed into the wet sponge. After you're through working with the syringe for the day, store it in a way that keeps the tip submerged in water. You can use a capped florist's water tube (for keeping cut flower stems fresh in transit during delivery) filled with distilled water and push the tip end of the syringe through the cap so that the entire tip end is submerged in water, or stuff a small piece of sponge inside one of those tubes, saturate it with water, and push the tip of the syringe through the cap all the way down into the wet sponge. With either of these methods, store the syringe (with the tipped kept wet inside the florist's water tube) sealed inside a zippered plastic bag. Or buy Linda's Lid, a glass jar with a special screw-on lid designed specifically for this purpose that can hold up to 4 open syringes upright with their tips submerged in a wet sponge (or just distilled water). Make sure to buy extra corks to seal the unused holes in the lid. Linda's Lid is available directly from the inventor, Linda Stiles Smith, in her Etsy shop NSCreativeElements as well as from several metal clay suppliers.
Here are some the uses of syringe clay:
- Use syringe clay to create a lacy "filigree" of metal clay over a combustible core, such as cork clay, wood clay, or even puffed cereal.
- Use syringe to create latticework or netting designs.
- Use syringe clay to create an outline of clay for freeform openwork designs.
- Use syringe clay to create dots and lines.
- Use syringe tips in different sizes and shapes to extrude different types of strands. You can buy syringe tips in several different shapes and sizes. You also can buy extra tips and modify them yourself to create even more shapes. For example, pinch opposite ends of the opening of a large, round syringe tip so it's more leaf-shaped and then cut a small V-shaped notch in the center to extrude leaf shapes with a center vein.
- Use syringe clay to attach silver metal clay components together, to join the ends of silver clay ring bands, etc.
- Use syringe clay to caulk cracks, small holes, or other small imperfections in dried or fired silver clay.
- Make a coil or nest of syringe clay as a bezel for a stone that can be fired in place. Learn more about how to set gemstones in metal clay using syringe (and many other methods).
- Use low-fire syringe clay to loosely but completely encircle a dichroic cabochon before firing. Continue the loop to create a bail, if desired.
Paper Clay / Sheet Clay
PMC and Art Clay make two slightly different versions of this paper-like form of silver metal clay, which remains flexible even when completely dry. You can also roll out PMC Flex clay to one or two cards thick and use it for most of the same applications as metal clay paper.
Art Clay Silver Paper Type is about twice as thick as the PMC+ Sheet, so for certain applications you may want to "laminate" two sheets of PMC Sheet together for applications that require thicker or sturdier clay. Here's how Celie Fago taught me to laminate layers of PMC Sheet:
- Start by placing one piece of the PMC+ Sheet on a piece of nonstick sheet. Brush or mist the silver sheet very lightly with water, and then stack another piece of silver sheet on top of the moistened layer.
- Immediately smooth the top sheet against the bottom sheet with the sides of your hands, smoothing from the center of the clay out to the edges to press out any air trapped between the two layers.
- Cover the top layer with another piece of nonstick sheet and weight it down with a heavy book for at least 20 minutes, which will allow the water and pressure to bond the layers together securely.
- If you want to laminate three or more layers of PMC+ Sheet, don't add more than one layer at a time; wait until the previous layers have been weighted down under the book for at least 20 minutes before adding the next layer. (Don't forget to cover the top layer with nonstick sheet before weighting it down!)
When attaching commercial silver metal clay paper (not very thin sheets of PMC Flex) to another piece of metal clay (any form), be sure to use water or slip very sparingly so the paper doesn't disintegrate. Apply the water carefully to the back of metal clay paper only, place it on the clay to which you want to attach it, and then apply gentle pressure from the front to make sure it adheres securely to the clay underneath.
Tip: There is a smooth side and a slightly textured side (small dots) to the paper, so pay attention to which side you want up.
Here are some uses for silver clay paper:
- Create appliqués by cutting out shapes with a sharp scissor or craft knife or using craft punches or paper punches. Attach them to your design by lifting the underside of each appliqué with a barely damp brush, carefully sliding it off the brush exactly where you want it and pressing the dry top of the appliqué firmly.
Note: If you get water on the top of the paper, it will turn mushy and be ruined. Also, be very precise when sliding each appliqué off the brush, as you generally can't move it successfully once it touches the clay to which it's being applied.
- Create negative space appliqués with the leftover metal clay "paper" from which you cut or punched out shapes previously. Barely moisten a sheet of plain metal clay paper or rolled out lump clay, then carefully lay the punched or cut-out PMC Sheet or Art Clay Silver Paper on top of the backing sheet and smooth it evenly it from the center out toward the edges, taking care not to tear or distort the fragile paper "filigree." After firing, use the recessed areas for patina, enamels, or keum-boo accents.
I like this effect so much that I sometimes cut or punch shapes out of metal clay "paper" specifically to create a negative-space design. Of course, I always save the cutouts to use as appliqués on the same or other projects.
- Weave strips to create a woven silver fabric effect. Make sure to attach the loose ends of all the strips securely on both sides with a tiny bit of water. Roll out a backing sheet from lump clay to stabilize the woven "silver fabric". See my silver metal clay weaving tutorial for step-by-step instructions and diagrams.
Tip: Use a higher shrinkage silver clay for the backing sheet to create a domed effect.
- Create a bezel for stones that can't be fired in place with a strip of PMC Sheet or Art Clay Silver Paper. See "Recommended Links," below, for the link to order a reprint of Jennifer Kahn's "Metal Clay Bezel" article in the May 2005 issue of Lapidary Journal (now Jewelry Artist magazine). Better yet, order the book which includes an entire chapter that Jen wrote about her groundbreaking metal clay bezel technique. PMC Technic
- Create fine silver origami by cutting and folding PMC Sheet or Art Clay Silver Paper.
- Braid strips to use as decorative accents.
How to Make Flexible, Metal Clay Paper-Thin Sheet
Commercial fine silver metal clay paper (Art Clay Silver Paper Type or PMC+ Sheet) is a unique product that doesn't dry out with exposure to air. However, you can make your own paper-thin metal clay sheet with other types of slow-drying, flexible clay formulas. Clay formulas that dry hard with no flexibility are not suitable for this application.
Here is a video showing how to do this with NobleClays brand. Although NobleClays is no longer available, the video provides a useful demonstration that applies to any flexible formula. Be extremely slow and gentle when peeling away the plastic wrap to avoid tearing the very fragile, paper-thin clay, and always peel away the top sheet of plastic wrap from the clay and not vice versa. Then use the edge of a sharp craft blade to help you loosen and lift the edge of the sheet from the bottom sheet of plastic wrap.
Note: I would probably roll the clay inside a plastic report cover, placing the thickness spacers inside with the clay, rather than rolling it inside plastic wrap with the spacers on the outside of the wrap. The report cover doesn't wrinkle, so the very thinly rolled clay would be less likely to tear.
The following video shows how to add glycerin to hard-drying, non-flexible formulas to make flexible clay that can be used in a variety of ways, including rolling it out very thinly to create metal clay "paper." Be careful not to add too much glycerin, which alters the properties of the clay and can cause problems, such as making it crumbly or causing it to resist sticking to itself when making joins.
Tutorial: How to Make Flexible Metal Clay With Glycerin - With Hadar Jacobson
What's Your Favorite Type of Metal Clay?
Do you prefer to use the basic lump clay and paste forms of metal clay, or do you enjoy using syringe clay for embellishment (or as a strong alternative to slip)? Have you tried using silver clay sheet or paper type for bezels, embellishments, weaving or origami?