For rapid and precise hiding power measurements These charts have a unique surface which is readily wetted by waterborne or solvent borne paints, but from which the dried film can easily be stripped with adhesive tape. Not so easily as to produce undamaged free films. The stripping feature permits the dry film weight on a measured area to be determined precisely by weighing on an analytical balance before and after film removal. The spreading rate (H) and wet film thickness (T) can then be calculated from the following simple relationships:
H (m²/L) = A (cm²)·N·D (kg/L)/10 M(g)
H (ft²/gal) = 40.746 H (m²/L)
H (ft²/gal) x T (mils) = 1604.2
Where: H = spreading rate (m²/L), (ft²/gal). T = wet film thickness (µm), (mils) A = test area (cm²) D = paint density (kg/L) M = dry film weight (g) N = non-volatile fraction by weight of the applied paint
This procedure represents a break-through in reduced time for precise measurement of spreading rate (or wet film thickness) in the determination of hiding power. Not so easily as to produce undamaged free films.
For Visual Hiding Power Ratings These are sealed paint test charts with six stripes on a white field, ranging in shade from very light gray to black. The stripes are numbered 1 to 6, representing uniform steps of increasing contrast. The hiding power of the applied coatings is rated as the number of the darkest stripe that is completely (or almost completely) obscured, at a specified thickness or spreading rate. Form CU-1M is used for more practical large-area brush or roller applications as in ASTM D 5150. Applications on Form 24B are with a drawdown blade.
Large-area matte finish test surfaces for practical laboratory application testing of wall paints These charts are coated with a flat finish similar in texture and "tooth" to a typical trade sales flat wall paint. Paints can be applied by brush or roller with assurance that there will be no surface "skid" during application. The surface is well sealed so that both waterborne and solvent borne coatings can be applied with no penetration of vehicle into the substrate.
Wall-Matte Charts are an effective replacement for previously available Kem-Glo Test Paper and superior to that product in imperviousness and paper rigidity.
Hiding Power Charts for OEM Coatings These are used by industrial coatings laboratories, principally those involved with the automotive industry, to measure the hiding power of spraying enamels. The chart is attached to a steel panel and the test coating sprayed to produce a "wedge" varying from thin at one end to thick at the other. After drying, a location on the chart of adequate visual hiding or 0.98 contrast ratio is determined, and the film thickness measured electronically on the steel panel adjacent to that location. Conversely, a location of specified thickness is determined on the steel panel and the Contrast Ratio measured adjacent to that location.
Self-Adhering Hiding Power Labels These are pressure sensitive labels with a hiding power test pattern and a sealed, solvent-resistant surface. They are used primarily with metal panels on which the uniform surface provides no visual clue as to the thickness of an applied paint film. When placed on such a surface, the Monitor presents a contrasting feature by which to observe the hiding during spray application, thereby facilitating film thickness control. It adheres firmly, whether air-dried or baked, to present a permanent visual record of film opacity. The longer Monitors, M71 and M72, permit wedge application, with thickness and hiding power determination, as described with Spray Strips.
In addition to sealed and unsealed charts and cards, Leneta Co offers a variety of materials as standardized substrates. The materials described here offer a variety of absorbance, surface tecture and other characteristics which may be useful in evaluating a coating or stain.
For preparing free films of organic coatings This paper is sealed on both sides, one side glossy and the other matte. The glossy side has a silicone finish with balanced release, to avoid excessive crawling of solvent borne or waterborne coatings, while permitting easy stripping of dried films. It is recommended in ASTM D 4708 "Standard Practice for Preparation of Uniform Free Films of Organic Coatings" and can be used to prepare test films for ASTM D 2370 "Tensile Strength of Organic Coatings", ASTM D 1653 "Water Vapor Transmission of Organic Coatings Films", and other free-film test methods.