Seeing the work properly

Most defects are not made in the finish. They are made earlier and simply not seen — a sanding scratch, a filled hole that is still proud, an edge that is a fraction out — until the paint or lacquer goes on and shows all of them at once.

Light from above flattens everything

A ceiling light or a lamp over your shoulder fills in every shadow on the surface. That is pleasant to work under, and it is exactly why it hides things: a scratch with no shadow is a scratch you cannot see.

Light at the surface

Put the light low, close to the work and almost parallel to it, and the same surface looks completely different. Every ridge throws a shadow, every hollow fills with dark. Painters and floor finishers have worked this way for a long time: check the surface with raking light before the finish, not after it.

What to look for in a work light

• Cordless, so it goes where the work is — on the floor, on a ladder step, at the far end of a room with no socket.
• Good colour rendering, so a colour match made under it still matches in daylight.
• Stepless dimming, so the light shows the surface without glaring off it.
• A stand or base that holds any angle, because the low angle is the whole point.

Ten minutes with a light at the surface before the first coat saves the afternoon it takes to sand back and do it again.