Laboratory Metering Rods

When used on a precision surface such as the Diversified Drawdown Platform™, metering rods — also widely known as Mayer Rods, drawdown bars, or metering bars — offer a proven method of applying uniform coatings to paper, film, sheet, foil, and non-wovens. They have been used in the coating industry for a century, and are ideal for laboratory studies of clay, PVDC, and wax coatings; printing inks, paints, varnishes, and adhesives, especially those that are starch-, latex-, or wax-based. Opacity, color match, gloss, tack stength, drying rate, coating weight per unit area, dye uniformity, and other attributes can be easily evaluated.

The test is simple to perform, economical, and offers easy cleanup with water, alcohol, appropriate solvent as required, and lint-free cloths. For best results, the rods should be cleaned and thoroughly dried between uses. Keep in mind that compressed air — a fast, non-contact drying technique – generally contains trace amounts of oil, and should not be employed.

The rods are fabricated from 303 stainless steel; the wire winding is 304 stainless steel. For relatively low viscosity coatings, the wet film thickness applied will be approximately one tenth the diameter of the wire winding. For example, a #10 metering rod is wound with .010″ (10 mils, or 254 microns) diameter wire, which will apply a coating of .001″ (1.0 mil, or 25.4 microns).

Mayer rods are ideal for dyne testing — they apply a uniform wet film thickness, which is an important determinant of accuracy and replicability, and they enable you to evaluate wetting over a large area in one test. The latter attribute is especially helpful for evaluating surface contamination or identifying systematic surface treatment patterns, which can be used to diagnose alignment problems in your corona treater. For dyne testing, we recommend using rods with #3 wire — these will meter the test fluid to a thickness of about .0003″ (0.3 mil, or 7.6 microns). Thinner fluid films are extremely difficult to maintain and see; thicker films will be less sensitive to purely surface effects.

Our lab rods are 16″ (406mm) in length, with 12″ (305mm) of wire wound on center* — the drawdown is wide enough to evaluate two or more coatings simultaneously. They are available in 1/4″ (6.3mm) or 1/2″ (12.7mm) diameter. For pricing and a list of our stock rod sizes, please scroll down the page. Intermediate wire sizes are available by special order, as are formed, double wound, or gapped lab rods up to #250, which can apply a coating as thick as .025″ (25 mils, or 635 microns). We can also supply other rod diameters and lengths to fit the drawdown equipment you use in your lab, regardless of manufacturer. Quantity discounts are based on the total number of metering rods purchased, even when splitting your order over rods of different diameters or designs. Please call or email us for quotes on non-stock lab rods.

*Rod size #0 is not wound. Rod size #1.5 is formed. Stock rod sizes #80 and #100 use a gapped winding. By special order, double wound rods are available from #10 upwards; gapped rods are available from #30 upwards; formed rods are available for most coating thicknesses. A description of the various rod types is shown here.