WET FILM THICKNESS GAUGE

WET FILM THICKNESS GAUGE

Wet Film Thickness Gauges are designed to measure the thickness of coatings immediately after they have been applied to a substrate. The gauge has a series of notches cut into its sides like the teeth on a comb. The wet film thickness of coatings including paints, resins, lacquers, varnishes and gels etc can be measured. It is a very simple and quick tool for measuring the film thickness of the wet film. A wet film comb is a rectangular piece of metal or aluminium with “teeth’’ of various lengths, each representing a different film thickness. The longest teeth are at the top and bottom of each side of the rectangle.

  1. Wet film comb/card thickness gauge
  2. Rolling wheel wet film thickness gauges

Wet film comb/card thickness gauges

Description:

A comb is a flat plate made of corrosion-resistant material with teeth along its edge. The reference teeth at the corners of the plate define a baseline along which the inner teeth are arranged to give a graduated series of gapes. Each tooth is labelled with the assigned gap value.

With commercially available comb gauge the maximum thickness which can be measured is typically 2000  and the smallest increment is typically 5

Procedure:

  • Ensure that the teeth are clean and not worn or damaged
  • Place the gauge at a 90° angle to the coated substrate
  • Make sure the gauge is in firm contact with the substrate.
  • Remove the gauge in a straight line up.
  • Assess the teeth of the gauge. The wet film thickness lies between the largest tooth that is wet and the smallest tooth that is not wet.

Rolling wheel wet film thickness gauges

Description:

A wheel gauge consists of a wheel, made of hardened and corrosion-resistant steel, with three projecting rims. Two rims are ground to the same diameter and are configured concentrically to the wheel axle. The third rim has a smaller diameter and is eccentrically ground. One of the outer rims has a scale from the respective projection of the concentric rims relative to the eccentric rim that can be read.

With commercially available wheel gauges. The maximum thickness which can be measured is typically 1500 and the smallest increment is typically 2

Procedure:

Hold the wheel by its central spindle. Begin at a maximum thickness to reduce the risk of inaccuracy caused by surface tension. Roll the wheel through the wet film with side 1 in the diagram touching the substrate. Roll for at least one whole turn and slowly enough for wetting to occur. Roll the wheel backwards by at least one complete turn. The wet film thickness is read from the scale, at the end of the wetted segment of the middle circle, 2 in the diagram To use the wheel on pipes, measure across the longitudinal axis (lengthways) of the pipe. On rough surfaces, measurements will be made from the surface peaks and represent the minimum wet film thickness.



Leave a Reply