An autoclave tape test for vacuum-assisted steam sterilizers devised by J. H. Bowie (1909–84) and J. Dick, and first described in 1963. It used a chemical indicator to detect the presence of air due to air leaks or inadequate air removal and steam penetration. The autoclave tape, through its steam sensitive indicator ink, changes colour at certain temperatures in the presence of moisture; a failure to change colour indicates the presence of air pockets and prevents the ink from undergoing a uniform colour change. The original test used 25–29 huckaback towels folded to give 8 thicknesses of cloth; strips of autoclave tape in the shape of a St Andrew's cross were then inserted at various intervals and the pack placed in a cardboard box or wrapped in fabric. Minimum safety factors for the Bowie–Dick test are defined within European Standards (ENs) and International Standards Organization (ISO) standards.
Bowie J. H., Kelsey J. C., Thompson G. R. The Bowie and Dick autoclave tape test. The Lancet 16 March 1963:586–7.