Underglaze Safety

Safe colour for ceramic studios

Kiwi Underglaze is a water-based liquid ceramic underglaze designed for everyday studio use. Smooth to apply, vibrant after firing, and made for normal brush-on application in ceramic studios, classrooms and home workshops alike.

Like all ceramic materials, it should be used with sensible studio care and good pottery practices. Used as intended, Kiwi Underglaze is low-dust, easy to work with, and designed to fit naturally into a safe and responsible pottery practice.

What’s in Our Underglazes?

Lead-free zone! Kiwi Underglaze is 100% lead-free - always has been, always will be.

We put a lot of care into crafting our ceramic underglazes, making sure they’re safe, reliable, and fun to use. Like all ceramic materials, they need a little respect and proper handling - but here’s the good news:

Some colours contain metal-based ceramic pigments. Some red, orange and yellow shades may contain encapsulated cadmium pigments. These pigments are manufactured so the cadmium compounds are incorporated within a stable zircon crystal structure, which significantly reduces solubility and bioavailability compared with non-encapsulated cadmium compounds.

Our products also contain crystalline silica, as many ceramic materials do. Because Kiwi Underglaze is supplied as a liquid and intended for brush application, respirable airborne dust is not expected under normal use.

The key safety point is simple: keep ceramic materials out of the air. Do not sand dried underglaze without appropriate precautions, and avoid application methods that create airborne particles unless suitable ventilation and respiratory protection are used.

Intended use

Kiwi Underglaze is designed for application onto ceramic ware using normal studio techniques such as brushing, sponging, detailing and other low-energy decorative methods. It is intended to be fired in a kiln as part of the ceramic process and may be used beneath a suitable clear glaze when creating functional food-contact ware.

Kiwi Underglaze is supplied as a liquid product for normal ceramic studio use. It is not intended to be used in dry powder form, ingested, applied to the body, or aerosolised without appropriate ventilation and controls.

If spraying, sanding or other processes capable of generating airborne particulates are undertaken, appropriate dust extraction, ventilation and respiratory protection must be used.

Is It Food Safe?

Food safety depends on the finished fired ceramic, not the underglaze alone.

For functional ware, we recommend applying Kiwi Underglaze beneath a suitable food-safe clear glaze and firing it correctly according to the recommendations for your clay, glaze and kiln.

We do not recommend using unglazed underglaze surfaces in food-contact areas. Matte or unglazed surfaces can be more prone to marking, abrasion and wear over time.

The food safety of the finished piece depends on factors including the clay body, underglaze, glaze, firing schedule and the quality of the fired surface. Because these factors are outside our control, makers should ensure their finished ware is suitable for its intended use and carry out appropriate testing where necessary.

ACMI AP (Approved Product) Seal - Certified non-toxic, conforms to ASTM D 4236

Independently Certified for Artist Safety

Every Kiwi Underglaze colour carries the ACMI Approved Product (AP) Seal.

The AP Seal means our underglazes have undergone independent toxicological evaluation through the Art & Creative Materials Institute (ACMI) and are certified to contain no materials in sufficient quantities to be toxic or injurious to humans, including children, when used as intended.

All 50 Kiwi Underglaze colours are AP Certified.

Products bearing the AP Seal are evaluated through ACMI's toxicological certification programme and certified in accordance with ASTM D4236 and applicable US art-material safety and labelling requirements.

For artists, studios, schools and families, the AP Seal provides independent assurance that our products have been professionally evaluated rather than relying solely on our own safety claims.

AP certification relates to the safety of the art material when used as intended. It does not certify the finished ceramic piece for food contact. See the food-safety guidance above for information about functional ware.

Safe Studio Habits

A few quick tips to keep your creative space safe while working with pottery underglazes:

  • Wash hands after use.
  • Wipe benches and tools clean with a damp cloth.
  • Keep food and drink away from your work area.
  • Keep lids closed when bottles are not in use. Store upright and out of direct sunlight.
  • Avoid sanding dried ceramic materials wherever possible.
  • If sanding is necessary, use appropriate dust controls.
  • Work in a well-ventilated area.
  • Supervise children when using ceramic materials.

Safe Firing Practices

Firing pottery is magical - but it comes with a few safety rules:

  • Use your kiln according to the kiln manufacturer’s instructions.
  • Place kilns in suitable ventilated areas.
  • Avoid breathing fumes from firing.
  • Do not linger near the kiln during firing or cooling.
  • Use kiln furniture and shelf protection where appropriate.
  • Kiwi Underglaze contains a small amount of flux, so we recommend testing before placing decorated surfaces directly onto kiln shelves.

We Love Pottery & the Planet

  • Do not pour underglaze into drains or waterways. Consider using a sediment trap avoid particles entering drainage systems.
  • For small studio amounts, let solids settle, dispose of solids according to your local waste requirements, and avoid releasing concentrated ceramic materials into the environment.
  • Wipe spills promptly with a damp cloth or disposable towel.

Need More Details?

For detailed handling, composition and safety information, please refer to our Safety Data Sheet.

Download Safety Data Sheet

A Quick Reminder About Little Ones

Our Kiwi Underglaze collection is perfect for pottery pros, passionate hobbyists, and budding artists alike. But always supervise kids - underglaze isn’t edible, and just because it’s yellow doesn’t mean it’s banana-flavoured!

At the end of the day, we’re here to make your creative journey safe, fun, and full of colour.

Got questions? Drop us a line - we love talking pottery!

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