"He got his first solo show at the famous Ace Gallery of Los Angeles in 1968. By 1970, he was working with a local plastics supplier to develop a new polyester resin that could remain stable when cast in huge pieces. This resin, which bore Valentine’s name in the plastic company catalog, was revolutionary for what was possible in plastic. Accordingly, he made some massive sculptures afterwards, some getting close to two tons. In his later life he’s worked more with flat glass as the medium for his transparency studies."