The Elcometer 3540 Four-Sided Film Applicators are precision-ground stainless steel applicators with a flat-edged prismatic body, used to apply a coating of set thickness and width onto a flat, relatively strong substrate. Reliable test results depend on a uniform wet film: if the draw-down thickness drifts from panel to panel, comparisons of colour, hiding power, drying behaviour or film integrity become unreliable. These applicators control the gap geometry so each sample is laid down at a known, repeatable thickness.

The prismatic body distinguishes the two variants. The Elcometer 3550 Single Sided Film Applicator carries a single film thickness, while the Elcometer 3540 Four Sided Film Applicator carries four thicknesses on one tool, letting the operator rotate the body to the required gap. The Elcometer 3540 models cover thicknesses of 50, 100, 150 and 200 microns, and the Elcometer 3550 models are offered at 50 or 75 microns. Film widths range across 50, 75, 100, 150, 200 and 250mm. To calculate the total width of the applicator, add 40mm to the stated film width. The flat edges make the gauges easy to clean between coatings, and they are manufactured to high accuracy.

Both versions can be used in accordance with ASTM D 823-E, a recognised method for producing uniform films of coating material for testing. They can be drawn by hand or used with the Elcometer 4340 Motorised Film Applicator, and an optional calibration certificate is available. Used in coatings quality control and paint laboratories, they are supplied by BAMR, South Africa's authorised Elcometer distributor.