Higher coating thickness up to 500μm can be obtained using open wound bars.Ī standard procedure for testing substances that are applied in a liquid form, and then dry to a solid film, is to create a controlled, standardized test film of the substance, usually on a standardized substrate, such as a metal, plastic or paper panel. Close wire wound bars will produce coating layers from 4 to 120μm. The coating will pass through the gaps between the wires and level off at a uniform thickness. These applicators differ from the bar applicators as they consist of a metal rod wound with wire of varying thickness. These applicators are the most versatile manual applicator, but is also the least precise. This adjustable applicator has a metal frame with an adjustable "knife" that acts as the gap clearance. This tool combines the accuracy of fixed applicators with the versatility of adjustable applicators. It has 8 clearances in the form of a square frame. The square applicator is the more versatile than previously mentioned applicators. Square applicator or Octoplex applicator This applicator also has two clearances but features a U-shaped form instead of a straight bar. This is a wire wound bar at each end, the gap height is controlled by the wire diameter, very simple and very cost effective. This is the most common type of film applicator. This applicator has one, two or four clearances and contains a slanted trailing edge, also used for high viscous coatings. It is used for non-rigid substances and has a two sided opening in the center of the bar. Used for low viscous coatings, this applicator also has four different clearances built in. Used for high viscous coatings, this type of applicator has four different clearances built in, one on each horizontal surface. The drawdown process is governed by ASTM standard D823. The speed and pressure of the bar can be adjusted to allow for customization of the final film thickness. The most modern types of applicators use vacuum plates to hold the drawdown cards and allow a variety of application bars to be mounted. The use of an automatic film applicator guarantees consistent speed and pressure, providing repeatable and high quality results.Īutomatic film applicators vary in their construction. These variations can affect the quality of the drawdown and thus the measurements of film properties such as abrasion resistance, hiding power and gloss. When using an applicator manually, small variations in speed and applied pressure are inevitable. 4.2 Square applicator or Octoplex applicator.Applicators can be used either manually or automatically. Film applicators follow the ASTM standard D823. There are multiple types of bar applicators, their forms and uses are shown below. Even with high manufacturing tolerances, the actual wet film thickness can vary from 50% to 90% of the gap. Each bar will give a "theoretical wet film thickness" or, in other words, the thickness of the coating that should remain on the drawdown card after application. JSTOR ( August 2012) ( Learn how and when to remove this template message)Ī film applicator is a device used to evenly spread a substance, such as paint, ink, or cosmetics, over a substrate such as a drawdown card.Īpplicators are usually metal bars that are manufactured to high tolerances to give consistent, repeatable results.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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