Hump and Slump Molds for Pottery | PhotoPottery

Hump and Slump Molds for Pottery

These combination hump and slump molds are hand made in the USA, designed for pottery making in high and low fire clays. Create a wide variety of pottery pieces incorporating simple to highly complex design elements, each uniquely suited to slumping or draping clay. These plaster molds are lightweight - easy to handle, even large pieces; and, compact - 2 molds in 1 place on the shelf!

Click or tap mold for more info, including dimensions and samples.

*Dimension Note - The size shown on this page is for the hump mold, which is the outside surface. If the plaster mold is round, the dimensions shown are height of the hump mold, and the diameter is for the top of the mold when the mold is in the upright position. Click into the mold to see complete dimensions for both the hump and slump molds, including bottom diameter for round molds.

Size Chart

For the Slump Hump Molds, we've used a Size moniker, such as Size 1, which in and of itself is somewhat meaningless. For that reason, make sure to check out how a size translates to actual dimensions by viewing the dimension chart of the mold description page.

In general, the larger the Size number, the larger the mold. Currently Size 1 is small to medium, Size 2 is medium to large, and Size 3 is large to very large! The duality, such as small to medium is needed since these are two molds in one; The inside slump mold is always the smaller of the two.

Hump Molds also available in many shapes and sizes.

Quickly Slump Mold Pottery

Because plaster molds absorb the clay's water, you can often quickly make pottery using slump molds: as soon as the clay firms up and can support its shape, place a support such as a bat or piece of foam on top of the slump mold (fully covering the pottery, with a half inch or more on all sides of the support) and then flip the mold over. Slowly start to lift the mold upward. If it's ready to release, you will see it start to fall onto the support. Completely lift off the mold, and you're ready to start the next pottery piece!

You'll generally know it's time to remove your piece from the slump mold when you start to see it pull inward off the slump mold's support wall. The time varies based on the thickness of the clay, with thinner pottery pieces ready sooner.

Drape Mold Pottery

As with slump molds, draping clay on plaster hump molds can expedite pottery production, since gypsum draws the water out of the clay. Monitor clay on a hump mold often to determine if it's ready to be removed, the point at which it is firm enough to support its shape.

Clay shrinks as it dries as particles coalesce. On hump molds, there's no place for the clay to go as it shrinks except inward, since it's blocked by the mold itself. If the piece is multi-part, comprised of coils and slabs, it should be removed before too much shrinkage occurs, so that the joins do not separate. Even a solid slab can develop stress cracks if left on the mold too long.

Usually there's plenty of time to remove your piece from a hump mold. Just keep in mind when working on hump molds that you typically do not want to cover in plastic and wait a day or more to demold.

Our online demonstration of making pottery on a hump mold shows how to work with a hump mold and has more info on how you know it's time to demold.

Note that while clay on slump molds will, of course, shrink, it is not blocked by the mold. In fact, the reverse occurs, as the clay pulls inward, away from mold.

Slump Hump Mold - Round, Size 1

Price: $21.00

More Info, See Samples...