Speedpaints belong to the same family as contrast paints: heavily pigmented, translucent, and formulated to flow off raised surfaces into recesses so that one coat produces both colour and shading. Compared with conventional hobby paints, which are opaque and are built up in layers, they trade control for speed, and for a large force that trade is usually worth making.
What they are for
The use case is an army rather than a centrepiece. A unit primed light and given a single coat of speedpaint per area is a tabletop-ready unit in a fraction of the time conventional layering takes, and the result is consistent across models in a way hand-layering rarely is. Painters use them for the bulk of a force and switch to conventional hobby paints for characters, which is a sensible division of effort rather than a compromise on either side.
The quirks worth knowing
Being translucent, they depend entirely on the undercoat, so a light and even prime is not optional. They can reactivate when a second coat is applied over a dry first one, which lifts and moves the colour underneath, so overpainting needs care or a sealing coat between. Some colours dry noticeably shinier than conventional paint, which a matt varnish resolves at the end. None of these is a fault so much as a property, and all of them surprise people who treat the paint like ordinary acrylic.
Against ordinary hobby paint
Conventional hobby paints remain better wherever you want control: smooth blends, precise edge highlights, flat colour on a large panel, and anything where you intend to paint over what you have just done. Speedpaints are better wherever texture and speed dominate. Most painters end up owning both, and the honest way to choose between them is by what you are painting rather than by which is more advanced.
Questions people ask about speedpaints
What is the difference between speedpaints and normal hobby paints?
Speedpaints are translucent and shade themselves in one coat; ordinary hobby paints are opaque and are built up in layers for control.
Do speedpaints need a light undercoat?
Yes. They are translucent, so a dark or patchy undercoat swallows the colour. A light, even prime is what makes them work.
Can I paint over speedpaints?
With care. They can reactivate when wet paint is applied over them, so a sealing coat between is the usual advice.