— A Mesh to Micron Conversion Table can be made using this screen scale as its base with an opening of 0.0029 in. which is the opening in 200 mesh 0.0021 in. wire, the standard sieve as adopted by the Bureau of Standards of the U. S. Govt., the openings increasing in the ratio of the sq. root of 2 or 1.414 except in the sizes Nos. 65 to 200 …