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Underglaze vs glaze: what's the difference and when to use each

Underglaze is for color and drawing. Glaze is the glassy coat that seals the surface. Most pots that look painted use both.

Updated November 2026 · 7 min read

Plates with carved coloured decoration under clear glaze
Photo: Maryele, CC BY-SA 3.0, via Wikimedia Commons
The short version
  • Underglaze vs glaze: underglaze is a colored clay-based paint that does not run, so it holds crisp lines and drawings. Glaze melts into glass in the kiln, giving a sealed, glossy or matte surface.
  • Underglaze usually goes on greenware or bisque, then a clear glaze goes over it. AMACO's LUG and Mayco's Fundamentals list use on wet/unfired clay or bisque.
  • Underglazes in our catalogue often list very wide firing ranges, such as cone 06–10. Glazes are usually rated for a narrow band, such as cone 5–6 or cone 06–05.
  • For food surfaces, follow the maker's statement. AMACO says its Velvet underglaze is not for food contact unless covered with a glaze tested for lead and cadmium release.

Underglaze vs glaze confuses almost every new potter, partly because some products blur the line. The basic difference: underglaze is for color and design, and glaze is for the surface.

Underglaze is mostly clay and pigment. It behaves like thick paint, stays where you put it and fires matte unless covered. Glaze is mostly glass-forming minerals. It melts and flows a little in the kiln, fills the clay's pores and gives the finished surface its look and feel. This explainer compares them neutrally, shows how they work together, and gives picks for each from several brands. Every cone range and food-contact statement is quoted from the listing.

Underglaze

Opaque, paint-like color for drawing and design on greenware or bisque; stays put in the firing

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vs

Glaze

A glassy coating that melts in the kiln, seals the clay and gives gloss, matte or effects

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Picks from each side

Underglaze

Glaze

Underglaze vs glaze at a glance

Two layers, two jobs

UnderglazeGlaze
Main jobColor, drawing, patternSeal and finish the surface
What it isClay + pigment (a colored slip)Glass-forming minerals + colorants
Moves in the kiln✓ Stays put, crisp lines~ Melts and can flow or blend
When to applyGreenware, leather-hard or bisqueUsually bisque
Surface alone~ Matte, often slightly dry✓ Gloss, satin or matte, sealed
Needs a clear coat~ Usually, for function and shine✗ No, it is the top coat
Firing rangeOften wide (e.g. cone 06–10)Usually narrow (e.g. cone 5–6)
Opacity✓ Opaque when layeredClear, translucent or opaque
Mixing colors✓ Like paint~ Possible, but test fire
Food contact~ Per maker; many need a tested glaze on top~ Only glazes the maker lists as dinnerware-safe

Source: Clay at Home summary of manufacturer listing data

How each one behaves in the kiln

Because underglaze is mostly clay, it barely melts at normal firing temperatures. That is why it keeps fine lines sharp and why its listed ranges are so wide. AMACO says LUG-1 Black is "dark and smooth at cone 05, fluxes into a soft glaze-like surface at cone 6, and maintains a deep black tone with a soft sheen all the way to cone 10".

Glaze is designed to melt at a specific cone. Fire it too low and it stays dry and rough. Fire it too hot and it runs, sometimes off the pot and onto the kiln shelf. So glazes come with narrower ranges.

How many cones the listed firing range spans

Count of cones from the low end to the high end of each listed range (cone 06 through 10 = 16 cones)

Underglaze · Mayco Fundamentals, 06–10Underglaze · Mayco Fundamentals, 06–10: 1616Underglaze · AMACO LUG, 05–10Underglaze · AMACO LUG, 05–10: 1515Underglaze · Speedball, 06–6Underglaze · Speedball, 06–6: 1212Underglaze · AMACO SMUG, 05–6Underglaze · AMACO SMUG, 05–6: 1111Glaze · Mayco Stoneware, 5–10Glaze · Mayco Stoneware, 5–10: 66Glaze · AMACO Potter's Choice, 5–6Glaze · AMACO Potter's Choice, 5–6: 22Glaze · Penguin Pottery, 5–6Glaze · Penguin Pottery, 5–6: 22Glaze · Sax Gloss, 06–05Glaze · Sax Gloss, 06–05: 22Glaze · AMACO Teacher's Palette, 05Glaze · AMACO Teacher's Palette, 05: 11
Source: Clay at Home catalogue, computed from listed cone ranges

Speedball adds that its underglaze "can be fired at cone 10" beyond the listed cone 06–6. Check our cone chart to see what each cone means in degrees.

How to use underglaze and glaze together

  1. Apply underglaze to greenware or bisque

    Paint, sponge or draw your design. Two or three coats usually give solid color. AMACO's SMUG pans work like watercolors, and LUG and Mayco Fundamentals list use on wet/unfired clay or bisque.

    AMACO Semi-Moist Underglaze Set No. 1, 8 ColorsMayco Fundamentals Underglaze Class Pack, 12 Pints
  2. Let it dry, then bisque fire

    Many potters bisque after underglazing so the color is set before glazing. That also keeps it from smearing under a brushed clear.

  3. Cover with a clear glaze

    Brush, dip or pour a clear glaze rated for your clay's cone. AMACO says its C-11 Mixing Clear works well with most underglazes, though it can mute a few Velvet colors.

    AMACO Celadon C-11 Mixing Clear, PintPenguin Pottery Glossy Clear Cone 5-6, 64 oz
  4. Wipe the foot and glaze fire

    Clean the base or use wax resist, then fire to the glaze's cone.

Want an in-between product? Mayco Stroke & Coat is a glaze that brushes like an underglaze. Mayco says it goes on wet clay, greenware or bisque and fires glossy without a clear. Full how-to in how to glaze pottery.

Food contact: read the label

Makers word this carefully, and so should you. AMACO's Velvet underglaze listing says "not for food contact, unless covered with a glaze tested for lead and cadmium release in accordance with ASTM C738-94". Speedball lists its underglaze as "lead-free, dinnerware safe when used and fired as directed". Mayco lists Stroke & Coat as food-safe and dinnerware-safe when fired according to its directions. Penguin Pottery lists its cone 5–6 glazes as suitable for food-contact surfaces when fired to the specified cone.

"Food-safe" assumes correct firingFood-safe statements assume correct application, a compatible clay and firing to the right cone. Under-fired or crazed surfaces can leach. If you sell functional ware, consider lab testing for lead and cadmium release. The FDA explains the risk of lead leaching from glazed pottery.Source: FDA, lead-glazed pottery Q&A

Picks with dinnerware-safe statements are collected in best food-safe glazes and the food-safe ware hub.

Which to buy first

If you want to paint designs, start with a small underglaze set and one clear glaze at your cone. If you want rich surfaces with no drawing, start with a few glazes and skip underglaze for now. For classes and kids, underglaze class packs plus a low-fire clear are the usual combination. Mayco's Fundamentals pack has 12 pints listed for cone 06–10. Teaching a group? See the kids and classroom hub. For more products, read best underglazes and best glaze sets for beginners.

Mistakes to avoid

  • Leaving underglaze bare on a mug lip or inside. Cover food and lip surfaces with a suitable glaze, per the maker's statement.
  • Using the wrong clear. The clear must match your clay's cone. Some clears mute certain underglaze colors.
  • Applying underglaze too thin. One coat often looks streaky. Build two or three.
  • Smearing with a heavy brush. Bisque after underglazing, or dip or spray the clear.
  • Mixing up cones. A cone 05 glaze fired to cone 6 runs. See glaze defects for crawling, pinholes and crazing.
  • Sanding dry glaze without protection. Glaze materials contain silica. Wipe with a damp sponge instead.

Other options worth a look

Decorating gets easier with the right application tools. Xiem's 0.75" goat-hair glaze brush is made for even strokes of glaze, underglaze and slip. Pasler's underglaze pencils (cone 06–10) let you draw on bisque. OLYCRAFT underglaze transfers apply printed designs. Penguin Pottery's refillable wax resist pens keep feet and lines clean.

Comparing brands? Read AMACO vs Mayco glazes, or browse the glazes and decoration category.

How we compared

We summarized manufacturer listings for the underglazes and glazes in our catalogue, quoting listed cone ranges and food-contact statements as written. The cone span chart is computed from those ranges. We did not fire or leach-test any product.

VerdictChoose underglaze if you want color you control: drawings, lettering, patterns and solid color blocks that stay crisp, over a wide firing range, usually sealed with a clear glaze rated for your cone. Choose glaze if you want the finished surface itself, whether gloss, matte, layered effects or a sealed, functional coat, fired to its specific cone. For most decorated functional pots, use both: underglaze for the design and a clear the maker lists as dinnerware-safe on top.
Orton cone temperature chartOrton self-supporting cone temperatures for cones 022 to 10 at slow, medium and fast heating rates, in °F…

Questions

What is the difference between underglaze and glaze?
In underglaze vs glaze, underglaze is a colored clay-based paint for design that stays put in the firing. Glaze melts into a glassy coat that seals and finishes the surface.
Do you need to put clear glaze over underglaze?
Usually, yes, for shine and for functional surfaces. Underglaze alone fires matte, and makers like AMACO say some underglazes need a tested glaze on top for food contact.
Can underglaze go on greenware?
Many can. AMACO LUG and Mayco Fundamentals list use on wet/unfired clay or bisque, and AMACO SMUG lists unfired clay or bisque.
Is underglaze food safe?
It depends on the product. AMACO Velvet says not for food contact unless covered with a tested glaze. Speedball lists its underglaze as dinnerware-safe when used and fired as directed. Follow each maker's statement.
Why do underglazes have such wide cone ranges?
They are mostly clay and pigment, so they barely melt and hold their color over a wide temperature span. Glazes melt at a set point, so their ranges are narrower.
Is Stroke & Coat a glaze or an underglaze?
Mayco sells it as a glaze, but it brushes like an underglaze. Mayco says it goes on wet clay, greenware or bisque and fires glossy without a clear coat.

Sources

  1. FDA: Questions and answers on lead-glazed traditional pottery
  2. Orton: Pyrometric cones
  3. Digitalfire: Lead in ceramic glazes