Film applicators

The controlled application of a film of paint, coating, ink, adhesive or coating material is a fundamental stage in laboratory testing and quality control. Uniform application makes it possible to prepare comparable samples, reduce operator influence and assess the behaviour of the applied coating more clearly.

Film applicators are used to distribute material over a substrate at a fixed or adjustable thickness, according to the test to be performed. Instrument selection depends on the type of material, the substrate used, the required thickness, the desired repeatability and whether manual or automatic application is needed.

Film applicators for paints, coatings and surface treatments

Film applicators are used to prepare uniform layers of paints, coatings, inks, adhesives and similar products on flat or flexible substrates. They are used in coating laboratories, quality control, formulation development, comparative tests and application testing.

Film application makes it possible to assess characteristics such as coverage, opacity, levelling, flow, application performance, uniformity and material behaviour after application. To obtain more reliable results, it is important to select the correct applicator and work on a stable substrate suitable for the type of test.

Manual applicators with fixed, double and four-sided thicknesses

Manual applicators are suitable when film application is carried out directly by the operator. Bar applicators are suitable when a single defined thickness is required, while two-sided applicators allow two thicknesses to be selected using the same instrument.

When the test requires several application values, four-sided applicators allow four predefined thicknesses to be used by rotating the instrument to the required side. Frame applicators add a containment frame that holds the material during application, making the process more orderly when the material needs to remain within the applicator.

Cube applicators are instead a compact solution for tests on smaller areas, with the material poured into the instrument before application. They are useful when small samples need to be prepared or reduced quantities of material smaller areas, with the material poured into the instrument before application. They are useful when small samples need to be prepared or reduced quantities of material are used.

Adjustable applicators and Mayer rods

Adjustable applicators are suitable when film thickness must not be limited to predefined values. They allow thickness to be set according to the test, material and substrate used, making them useful in laboratories that need to perform tests under variable application conditions.

Mayer rods are spiral applicators used mainly for film application on flexible substrates such as paper, card, textiles, leather or materials compatible with this method. They can be made with wound wire or an extruded spiral. Their general function is the same, namely to obtain uniform films on flexible substrates; the difference is in their construction, as the grooves in extruded-spiral versions are formed directly in the rod.

Automatic film applicators for more repeatable application

Automatic film applicators are used when the application stage needs to be made more consistent. The system controls the application movement and helps reduce variability associated with the operator’s hand, preparing samples that are more comparable with one another.

It is important to consider that the automatic film applicator does not determine film thickness by itself. To perform the test, a suitable applicator must always be fitted: bar, two-sided, four-sided, frame, adjustable or spiral. The automatic system manages movement and application conditions, while the selected applicator defines the thickness and method of applying the material.

Versions with a vacuum pump are also available, useful when charts, paper or thin substrates must remain firmly adhered to the surface during application. Some models can also be selected with a heated plate when the test requires control of the surface temperature.

Charts, drawdown plates and supports for film application

For correct sample preparation, not only the applicator but also the substrate on which the material is applied is important. Charts for testing paints and coatings make it possible to assess coverage, opacity, application performance, levelling, uniformity and the behaviour of the applied film.

Charts with white and black areas help assess the hiding power of the coating, while contrast or chequered charts make differences in opacity and application performance more evident. Laminated versions or versions with a specific surface coating are useful when more stable, resistant or suitable supports are required for repeatable comparative tests.

When application is carried out manually, drawdown plates help keep the chart or substrate in place during application. Versions with a vacuum pump are suitable when the substrate is thin, lightweight or tends to lift during the test.

Complementary laboratory instruments

This section also includes complementary instruments for laboratory testing and preparation. The minimum film forming temperature tester is used to determine the minimum temperature at which paints, adhesives, emulsions or coatings are able to form a continuous, crack-free film.

Laboratory ovens are suitable for drying, curing and controlled heat treatment of samples and materials. Thermostatic water baths, on the other hand, make it possible to heat samples placed in a water bath and maintain their temperature uniformly.

How to choose the correct film applicator

The choice of film applicator depends first of all on the type of substrate and the required thickness. When the test involves a single application value, a bar applicator may be sufficient. When two or four predefined thicknesses are required, two-sided or four-sided applicators are more suitable.

When film thickness must be set freely, an adjustable applicator is preferable. When the substrate is flexible, such as paper, fabric, leather or card, Mayer rods are a dedicated solution for obtaining uniform film application.

For repeated tests, comparisons between formulations or activities where reducing operator influence is important, automatic film applicators make the application stage more consistent. When the substrate is thin or tends to move, the version with a vacuum pump helps keep it adhered to the surface during application.

The correct choice therefore results from the combination of material to be applied, substrate, thickness, application method and level of repeatability required by the test.