I was over at Atlas Screen Supply Company
trying to determine mesh to microns and came away confused. It may be best to give up on any simple conversion scale and go by what the retailer says a particular mesh is.
Okay, first the simple one. 125 mesh
Textile 125 Mesh (71 Microns)
That would be good for dry shift.
But I also found two different meshes that claim to be virtually the same in microns. 140 mesh
Textile 140 Mesh (54 Microns) 195 mesh
Textile 195 Mesh (55 Microns)
I've tried to compare what I've found on several silk screen supply web sites to several charts and it never agreed. I'd go with the silk screen web sites.
But hey, mesh is cheap, buy some 80 (100 Micron) and 125 (71 Micron) mesh and go from there.
Mesh 125 White 55" Width (Sold Per Yard)