• Underglaze Safety

What’s in Our Underglazes?

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:

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

Vivid reds & oranges: some of our fiery shades contain encapsulated cadmium. But don’t worry - it’s bonded with zirconium silicate, making it over 1,000 times safer than free cadmium.

Silica superstar: silica makes glazes more transparent, durable, and stable. It’s amazing stuff - but it’s best kept in your glazes, not in the air. Luckily, our underglazes are liquid, meaning less dust, less mess, and less risk.

Is It Food Safe?

Our bottles proudly state: “Food safe when fired correctly.”

If your Kiwi Underglaze masterpiece is finished with a durable clear glaze and fired to the right temperature, it’s ready to shine at the dinner table!

Matte finishes without a clear glaze, however, aren’t recommended for food. They can scratch easily, and small underglaze particles may come loose. If you’re unsure whether your piece is safe, get in touch - we’re always happy to help.

Safe Studio Habits

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

Keep it clean → Wash your hands and wipe down surfaces after use. Raw underglaze is not food-safe.

Let the air flow → Always work in a well-ventilated space, especially if you’re spraying.

Gear up → Wear a dust mask when sanding or spraying. Gloves are optional, but washing underglaze off your skin quickly is usually enough.

Go liquid → Our brush-on ceramic underglazes are easy to use and create far less dust than powdered alternatives.

Store smart → Keep lids tight, bottles cool, dry, and out of direct sunlight.

Safe Firing Practices

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

Check your kiln → Keep it in good working condition and place it in a ventilated area.

Mind the fumes → Firing releases gases, so ensure there’s proper airflow and avoid lingering near the kiln during firing.

We Love Pottery & the Planet

We care about your studio and the environment. Here’s how to stay eco-friendly with underglaze colours:

Dispose thoughtfully → Let solids settle before pouring leftover liquids away, and follow local waste guidelines.

Clean spills quickly → Use disposable cloths or paper towels, and toss them responsibly.

Need More Details?

If you’d like the deep-dive on composition, handling, and safety, check out our Safety Data Sheet (SDS). Just ask - we’ll send it straight to you.

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!

FAQ

You asked, we answered!

  • We have always used Ferro glazes (Ferro 6155 is what we use), as they seem to play well with Kiwi Underglaze! However, many people also use Amaco clear. In fact, we are not aware of any issues with any commercial glazes; quite often issues that have arisen in the past have related to home-made formulas.

  • There is a small amount of flux in the formula, so out of an abundance of caution, we do not recommend putting it straight on the shelf in case it sticks. 

    Personally, we do without any sticking issues! And we also have many customers who do. But to be safe, if you would like to - do a small test tile first.

  • Colour is brightest when clear glazed and fired to cone 4 or 5 (approximately 1180°C / 2150°F), but full glaze firing range is cone 04 to cone 9 (approximately 1050-1260°C / 1920-2300°F).

  • If you’ve finished your Kiwi Underglaze masterpiece with a durable clear glaze and fired it to the appropriate temperature (105 -1260 Celsius /1920 - 2300 Fahrenheit), congratulations—your creation is ready to shine at the dinner table! However, if you’ve opted for a matte finish without a clear glaze, we don’t recommend using it for food. Matte surfaces can be more prone to scratching, which could lead to bits of underglaze coming loose.

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

    Vivid reds & oranges: some of these fiery shades contain encapsulated cadmium. This means that the cadmium is bonded with zirconium silicate, making it over 1,000 times safer than free cadmium.

    Silica superstar: silica helps give your finished glazes transparency, durability and stability, it’s amazing stuff! But it’s best kept in your glazes, not in the air where you can breathe it in. Luckily, our underglazes are liquid, which means less dust and less risk for you.

  • Our underglaze range is designed primarily for the midfire range. It has a wider range in which it will harden on and be foodsafe, but as with all things ceramics – whether it is clay, glaze or underglaze, you are going to get different colours at different temperatures. That the boldest colour will be achieved at around cone 4-6 (midfire). This is where the colours really pop!

  • Our underglazes are for pottery pros, passionate hobbyists and budding artists alike, but make sure the kids are supervised when using them. Having them test out whether yellow underglaze is banana flavoured isn’t going to be the best of fun!

  • When left unglazed and fired to around cone 06 (1000°C / 1800°F) or more, the colours assume a velvet matte appearance. This is a good surface for sculptural forms and as a decorating effect where glazing is not essential.