Non-Toxic Materials and Processes

We are committed to clean manufacturing and non-toxic finished products.


Our clay comes out of the ground in Ohio USA.  It is a high-iron content clay called Red Art. Iron is what makes our clay - and all terracotta - reddish colored.

To make the clay liquid and pourable, we add 2 deflocculants to the clay, along with water.  They are sodium silicate and darvan.  Sodium silicate is a salt that is used in many technical applications, including some cosmetics and food preservation.  Darvan is a synthetic compound similar to sodium silicate in function, and is not known to be toxic.

Clay ingredients: Red Art clay; water; darvan; sodium silicate

Note:  Most terracotta formulations contain barium carbonate (a common rat poison), but we reformulated our clay to eliminate it.


All our glazes are lead-free.

The main body recipe of our glazes is comprised of commercial frits (glass-forming materials), silica, and clay.  

The colorants we use are: Cobalt carbonate; copper carbonate; mason stains.

We use zircopax (zirconium silicate) as an opacifier - to make our Stinson glaze an opaque color, and to make Fog a lighter blue.

We are careful to fire our glazes to maturity so that the cobalt and copper cannot leach out.  But if you are avoiding these materials, our Stinson glaze is free from all colorants.

Mason stains are proprietary formulas, but they are guaranteed to be lead-free.  None of the glazes in production currently (Fog, Bat Ray, Stinson, Lichen, Dirt) contain any mason stains, but we do occasionally use them.

Our glazes are formulated to require only one firing to save energy.  (Most terracotta is fired twice.) We dip our glaze, rather than spray, in order to keep particulates out of the air.


We package and ship in 100% paper packaging that you can either recycle or compost.  We're proud to work with EcoEnclose to source shipping labels that are BPA free and use a recycling-friendly adhesive.

Heavy Metals

We get a lot of questions about heavy metals in our products.  This is a complicated topic, as there are many heavy metals, some of which are harmful, and others which are not.  See this Wikipedia article for details.

Chromium, arsenic, cadmium, mercury, and lead are the main heavy metals of concern in products.  We do not use any of those materials.

However, there can be trace amounts of all metals in soils and clay.  Because our clay base, Red Art clay, comes directly from the earth, background trace amounts of all elements may be present.

Iron is technically a heavy metal, but is a required nutrient, and is present in fairly large quantities in our terracotta clay.  (Iron is what makes terracotta red!)

We use cobalt and copper in very small amounts in the following glaze colors: Fog, Bat Ray, Lichen, Dirt.  When glazes are fired to maturity, the metals are enclosed in glass and cannot leach out.

Handmade Responsibly in California

We make all our clay and glazes from raw materials in our California studio.  We control every aspect of the process to make sure we know exactly what we're selling.