How to Use Underglaze
A practical guide to applying, firing and finishing Kiwi Underglaze — from your first coat to your first kiln load.
Quick start
There's plenty more below, but these five will get you a long way.
Shake it well
Pigments settle. Give the bottle a proper shake before you start.
Thin layers win
Build colour with thin, even coats rather than one heavy coat.
Let each coat dry
Let one coat dry before brushing on the next.
Know your firing
Kiwi works across a wide firing range, with colour brightest around cone 3–6.
Test your combination
Clay, underglaze, clear glaze and firing all interact. Test before committing to an important piece.
How to apply
A few simple things make a big difference. Here's how to get Kiwi brushing smoothly and building colour evenly.
Pigments naturally settle, so shake well before you start. If a colour has been sitting for a while, give it an extra-good mix.
Kiwi should brush on easily in a thin, even layer. If it feels thick or draggy, stir in a small amount of water. Don't thin it more than you need to.
Repeatedly brushing over underglaze as it starts to dry can lift what's already there and leave an uneven surface.
Let the surface lose its wet sheen before going back with another coat. Painting repeatedly into a damp layer can disturb the coat underneath.
Want stronger colour? Add another thin coat rather than loading on one heavy coat. Heavy application is much more likely to cause cracking, peeling or glazing problems.
Residual colour in a brush can muddy the next one, especially with pale colours.
Brush away dust before painting. Dust creates a barrier between the underglaze and clay.
Wet, dry and fired Kiwi can all look a little different. The colour develops again during firing.
Firing & colour
Kiwi works across a seriously wide firing range, from cone 04 right through to cone 9. But temperature can influence the colour you see at the end.
At lower temperatures, Kiwi colours tend to fire softer and more pastel, with less intensity than you'll see higher up the range.
This is where Kiwi really comes alive. Colours are generally at their brightest, richest and most vibrant through this range.
Kiwi is designed to keep performing right through to cone 9. At higher temperatures, some colours may shift, soften or become more muted, so test when colour accuracy matters.
Firing temperature is only part of the picture. Your firing schedule, clay body and clear glaze can all influence the final colour, so if an exact result matters, test the combination first.
Some colours barely shift across the range; others respond more noticeably to heat.
Matte or gloss
Same Kiwi. Two very different finishes.
A natural, velvety finish with the underglaze surface left exposed.
Decorative pieces, sculpture and surfaces where you want that soft, tactile finish.
Because the underglaze surface is exposed, it can mark, scratch or wear more readily than a glazed surface.
Clear glaze adds shine and depth and can make colour appear richer and more saturated.
Functional pieces and surfaces where you want a more durable, easy-to-clean glazed finish.
For pieces that will come into contact with food, cover Kiwi with a suitable food-safe clear glaze and fire it correctly according to the glaze manufacturer's instructions.
Go easy on the clear — a heavy clear-glaze application can sometimes cloud or soften the colour underneath. An even application generally gives the cleanest result.
Get even more from your Kiwi.
Kiwi can look different wet, dry and fired. A fired test tile is the best way to see how a colour will look with your clay, glaze and firing.
Working on bisque? A quick brush with a clean, dry brush removes surface dust and gives your underglaze a clean surface to work on.
Make your testing repeatable. Note the clay, Kiwi colour, number of coats, clear glaze and firing cone so you can recreate the results you love.
Different clear glazes can give the same Kiwi colour a slightly different look. Test your favourite combinations and you'll know exactly what to expect.
Paint colours over one another, blend them or build up layers for more depth. Let each layer dry before working over it.
Kiwi colours mix beautifully, so experiment with your own shades. Start small and note the proportions when you find one you love.