silk sieve fabric

Silk fabric woven to sieve mustard powder at Colman's Mustard factory, Norwich to achieve high quality mustard powder; mesh on this sample is 28 x 28 i.e. 28 threads per square inch 784 holes per square 1/4 inch; silk was also woven in other combinations (all much finer than this example) up to 40 x 40, i.e. 1600 holes. the silk determines the grade of mustard flour which was blended into many different brands marketed prior to 1955; numbers at side edges; blue threads in weave identify this piece as being worked by Olive Weston