Two mugs can look exactly alike in a shop photo and have nothing in common six months later. One has kept its colours, the other has a design cracking around the handle. The difference is invisible at purchase: it is decided at the moment of printing.
The real question: is the ink on top, or inside?
Every printing method on ceramic falls into one of two families, and that is the only distinction that matters in use.
In the first, the ink is laid on the surface. It forms a film on the mug. To the touch you can often feel a slight thickness, a ridge where the design begins. That film takes everything: heat, detergents, the rubbing of the dishwasher basket. Eventually it peels, usually starting at the edges.
In the second, the ink penetrates the coating. There is no added layer: the design is part of the mug. The pattern is perfectly smooth to the touch, indistinguishable from the rest of the surface. That is the principle of sublimation.
How sublimation works
The process rests on a physical property: under heat, the ink passes directly from solid to gas without becoming liquid. That change of state is what sublimation means.
The design is first printed onto transfer paper. The paper is pressed against the mug, and the whole thing is brought up to temperature in a heat press. Under heat the ceramic coating opens at a microscopic level, the gaseous ink enters, and cooling closes it back up. The ink is then trapped beneath the surface.
The direct consequence: there is nothing to flake off, because nothing sits proud of the surface. This is the process we use across all our PMW mugs, in high definition.
The ten-second test
You can check this yourself on a mug you already own. Run a fingernail across the boundary between the design and the bare ceramic. If you feel a step, however slight, the ink is on the surface. If the transition is completely smooth, it is sublimation.
The other methods, and where they legitimately belong
No method is bad in absolute terms — they answer different needs.
Vinyl transfer
A coloured film is cut then heat-bonded. Solid on textiles, noticeably less so on ceramic that goes through the dishwasher. It allows neither gradients nor photographs: each colour is a cut-out block.
Screen printing
Excellent durability and very dense colours, but it requires one screen per colour. The setup cost only pays off from several hundred identical pieces. This is the method for large industrial runs, not for original designs or limited editions.
Fired decals
The design is re-fired in a kiln at high temperature. This is the most durable technique in existence, used by porcelain manufacturers. In return it imposes strong constraints on the artwork and a heavy process, reserved for mass production.
What sublimation allows, beyond durability
Because the design is printed as an image rather than cut out, sublimation allows gradients, photographs and fine textures. That is what makes an ink illustration with its shadows possible, or a screen-printed poster reproduced with its grain.
It is also what makes one-off personalisation economically viable: printing a single piece costs the same per unit as printing fifty. A mug personalised from your own photo is therefore not an exceptional product, simply another image sent to the press.
Looking after a sublimated mug
Our mugs go in the dishwasher without reservation. One useful clarification: very hot cycles and aggressive detergents gradually dull the gloss of the coating — not the design itself, which sits underneath. A gentle programme therefore keeps the finish bright for longer, without being a condition of the design’s survival.
The microwave poses no problem on ceramic with no gilding or metal. Ours have none.
In short
- The only criterion that matters: is the ink on the surface or in the coating?
- Sublimation places the ink beneath the surface — nothing can flake off.
- Check by touch: a smooth design is sublimated, a raised one is not.
- Sublimation alone allows photographs and gradients as one-offs.
More questions about our mugs? Our FAQ answers the most common ones.