Bridget Riley made her first print in 1962 when an admirer of her painting Movement On Squares suggested it would make a great print.

"I had never made a print in my life," Riley recalls. "For me, prints were what you saw in the British Museum, with that very hand-made look."

She did, however, make the print and the limited edition of 26 quickly sold out. Since then, she has stretched the process, demanding more of her printers with each new development.

Her latest, Composition With Circles 2 (2001), made for her exhibition at the DIA Centre For The Arts in New York, required a new screen due to it being more than three metres long. It is the largest her New York printers have ever made.

Chiefly a painter, practicality helped determined the sporadic bouts of Riley's printmaking.

At the beginning of her career, making prints came out of the desire to explore ideas, possibilities and variations that couldn't all be evolved into paintings.

Then, in 1971, when the budget for an exhibition was threatened, Riley suggested making a series of prints based on the paintings in the exhibition to raise funds.

The British leader of Op art (Optical art), Riley's aesthetic lies in her interest in the effects of shape and colour.

The repeated patterns and subtle variations of controlled, hard edges of shapes and lines in her prints fool the eye into seeing vibrating and flickering movement. The surfaces of her prints seem to pulsate, swell or warp.

The effects of her designs have been tried and tested. Fascinatingly, a scheme she created for the interior of the Royal Liverpool Hospital that purposefully used soothing bands of blue, yellow, pink and white has caused a drop in vandalism.

Surprisingly, this is only the second exhibition of her prints (the first was 20 years ago) as museums and galleries have tended to focus on her paintings.

The sensational 40 prints and three paintings in this exhibition have been chosen by the artist herself.

The selection of work demonstrates how Riley's style has evolved over the past four decades, from the black-and-white prints she first produced in the Sixties to her adept range of colour - such as the Egyptian palette, inspired by the colours of ancient Egyptian art following a trip in 1981.

This is a great chance to see such a collection of Riley's prints together.

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