or groove 7 a on seal 7 the doctor assembly 11 a comprises the carrier bed or support 11 for the doctor roll or bar 12 the bed or carrier 11 is made of uhmw polyethylene or similar material the doctor roll or device 12 can be a solid bar fig3 or a hollow tube fig1 or 2 with or without grooves on its outer surface if solid the doctor device is consequently generally of a smaller diameter than a hollow rod type doctor roll either type of doctor roll may be driven to rotate in a direction usually opposite the direction of the moving surface travel be it a web or roll surface the doctor 39 s diameter can range from u215c u2033 to 1 u00bd u2033 if a hollow tube is used for the doctor device 12 it can be of sweated construction with cold water flowing through its center a curved bar 13 supports the front of the support 11 the curved bar 13 is clamped to the main coater by an air pressurized clamp tube 14 the upper surface of the curved bar 13 as shown in fig1 forms a side of the application zone and seals against the edge dam assembly reliefs or cutouts 15 are provided in the support 11 for the doctor bar 12 these reliefs allow the bar 12 to rotate more easily lateral grooves 16 with the pipe taps or other type connections are provided in either end of the support bed 11 water is provided to these connections and circulated through these grooves or channels 16 to clean.