What Is Casting Slip and How Do You Use It?

If you've seen perfectly uniform, detailed ceramic pieces and wondered how they're made without hand-building or a wheel, the answer is often slip casting — and it starts with casting slip.

What casting slip actually is

Casting slip is clay in liquid form, specially formulated to flow smoothly and pour easily without needing to be thinned down with excess water (which would weaken the final piece). It's poured into a plaster mold, and that's where the process gets interesting.

How the mold does the work

Plaster is naturally porous, and it draws water out of the slip that's touching its surface. As water is absorbed, a layer of solid clay builds up against the inside of the mold. Once that wall reaches the thickness you want, the remaining liquid slip is poured back out, leaving a hollow, evenly-walled clay piece behind — let it firm up a bit more, then carefully remove it from the mold.

Why use slip casting at all?

It's the most practical way to reproduce the same detailed shape over and over with real consistency — something that's genuinely difficult to match by hand-building repeatedly. It's how a lot of the smaller, more detailed bisqueware pieces you'll find are originally produced.

Matching slip to your firing plans

Casting slip comes in different clay bodies — low-fire and stoneware among them — and each one needs to be matched to an appropriate firing temperature, the same as any other clay body. Check the cone range on your slip before you commit to a firing schedule.

Get started

Browse our Slip collection for ready-to-use casting slip in multiple clay bodies.