Playing a Test match into the evening required a ball that behaves like a red one and remains visible under lights. Pink was the compromise, and it changed the balance of the format in ways that are still being worked out.
The red ball fails under floodlights
A red ball is easy to pick up against grass in daylight, which is why the longest format has used it for well over a century.
Under artificial light and against a darkening sky, red loses contrast badly, and batters lose sight of the ball at the point where reaction time is shortest.
Because a Test is played over long sessions, that visibility problem could not be solved by playing only in daylight without abandoning the evening audience.
The white ball cannot last long enough
Limited-overs cricket uses a white ball, which is clearly visible under lights and is the obvious first candidate for evening play.
It discolours quickly, however, picking up grass stains and dirt, which is manageable when two balls are used across a shorter innings.
A Test innings can last far longer with a single ball, and a white one would become effectively invisible before it was due to be replaced.
Pink survives both requirements
Pink holds contrast against both grass and a night sky, and it retains that contrast for longer than white because the pigment is applied differently.
Manufacturers use a coloured finish over the leather rather than dyeing it through, and the seam is stitched in a contrasting thread so bowlers and batters can read it.
The result is a ball that stays visible across a long innings, though the extra coating changes how the surface wears as the innings progresses.
The ball behaves differently through the evening
The lacquer that keeps the pink ball visible also keeps it hard and shiny for longer, which extends the period in which it swings.
Under lights, and particularly during the twilight period when natural and artificial light mix, batting has proved noticeably harder than in daylight.
That produces clusters of wickets at predictable times, and captains structure declarations and bowling changes around reaching that window with the right bowlers available.
Preparation had to change with it
Grounds leave slightly more grass on the surface for these matches, because the pink ball scuffs faster on a dry pitch and the coating comes off.
Extra grass keeps the ball intact but also assists seam bowling, which compounds the advantage the evening session already gives to the fielding side.
Balancing those factors is still an open problem, and it explains why results in these matches arrive faster than in conventional Tests. Draws are rare where the evening session is this decisive.
