An exhibition of forged iron- work by members of the British Artist Blacksmiths Association, opened last week at the Fire & Iron gallery in Leatherhead, Surrey. Many of the artists admit to being fascinated by iron. Unlike most metals, which are relatively malleable when cold, iron and steel are a tougher, more demanding medium. Susan May, a jeweller by training, says, 'It's quite magical, because it's incredibly soft when it's hot, but as soon as it cools down, it becomes really rigid and immovable again.' Ann Catrin Evans' mild steel door-knockers and handles seem to have been inspired by those bleak castles that are a stock feature of horror films. One of her designs is like a ball and chain, another like a Celtic cross. 'I love the fact that steel is cold and hard,' she says. 'And the way it feels as though it's there forever.' No other base metal can have given man as much visual pleasure, or a greater feeling of security. The chances of iron being used decoratively for the next thousand years are good, to say the least as long as we don't have to look at any more rusty candlesticks, that is.