Decals and transfers are printed ceramic colour on a carrier film, and they put photographic or repeat imagery onto pottery in a way no brush can. What confuses buyers is that several different products share the names, and they go on at different stages and fire to different temperatures.
On-glaze decals
The most common kind: printed colour applied over an already fired glaze and fired again at a low temperature, typically several hundred degrees, so the colour fuses into the glaze surface. They give bright, detailed and photographic imagery, including gold and lustre effects, and the low firing means a domestic-scale kiln handles them easily.
Underglaze transfers
Applied to bisque before glazing, then covered with a clear glaze and fired at full temperature. The image ends up under the glass rather than on it, which makes it far more durable and dishwasher resistant, at the cost of a smaller colour range, because fewer pigments survive stoneware heat.
How to apply one
Soak the sheet in water until the film slides on its backing, position it on the ware, and squeegee the water and air out from the centre with a soft rubber kidney. Trapped air becomes a blister in the firing and trapped water becomes a bubble, so the pressing out is the whole technique. Let it dry fully before firing.
Buying and having them printed
Suppliers stock standard decal sheets, and specialist printers will produce custom ceramic decals from your own artwork, which is how makers get logos and repeat patterns onto ranges. Check which firing type a sheet is for before ordering, because an on-glaze decal fired to stoneware temperature will simply burn away.
Questions people ask about underglaze
What is the difference between a decal and a transfer?
The words are used interchangeably. What matters is whether the product is on-glaze, fired low over a finished glaze, or underglaze, fired under a clear at full temperature.
Are ceramic decals dishwasher safe?
Underglaze transfers under a clear glaze are the durable option. On-glaze decals sit on the surface and wear with use.
Can I have my own design printed?
Yes. Specialist printers produce custom ceramic decals from artwork, which is how small makers put logos and repeat patterns on a range.