BYK INSTRUMENTS - Physical Properties
Description
Abrasion resistance is an important property for paint and coatings.
An abrasion test is also common for tile, flooring, furniture, wall coverings, shower stalls, and bath tubs. The abrasion tester produces a repeatable, controlled condition to simulate everyday use or wear pattern.
The abrasion testers have a flexible design to use brushes, sponges, abrasive pads, and sand paper to wear the surface.
Besides testing scrub abrasion, the gardner-scrub can also be set up for washability tests. For other application specific tests such as stain resistance and detergent testing special modification kits are available.
Description
In order to perform satisfactorily, coatings must adhere to the substrates on which they are applied. There are three different adhesion test procedures to assess the resistance of paints to separate from the substrate.
The cross cut test, also described as cross-hatch, uses a blade to cut through the coating to the substrate.
At least two cuts are made that intersect at 90 degrees to get a right angle lattice pattern. The cross-cut area is observed for any adhesion failure. The second method evaluates scrape adhesion using a stylus or loop that is loaded with an increasing amount of weight until the coating is removed from the substrate.
The third method called pull-off adhesion, measures the amount of tensile stress to pull the coating off the substrate. A dolly is glued to the coating surface.
Description
Paint thickness is an essential parameter that needs to be measured routinely. The proper film thickness has an impact on the paint opacity, appearance, and protective properties of the coating. Applying too much coating can also be detrimental that can lead to excessive drying time, cracking, and flaking of the paint film. Coating thickness measurement will monitor the paint process and maintain the appropriate coating properties.
Measuring the film thickness immediately after coating the surface is important to control the spreading rate and the final dry film thickness. Wet film thickness should be monitored frequently to maintain an efficient coating process. A wet film thickness gage is an inexpensive, easy to use device. They cover a wide wet film thickness range from industrial maintenance applications to thin coil coatings. Wet film gages can be used on virtually every substrate.
Paint thickness gauges for dry film thickness can either be a non-destructive measurement or destructive measurement. The non-destructive paint gauge uses measurement principle of magnetic induction for ferrous substrates and eddy-current for non-ferrous substrates.
The generally accepted ratio of dry film to wet film thickness of most coatings is:
Wet Film x % Volatile Solids of Coating
Dry film = ————————————————
100
Description
Dispersers provide the mechanical energy to breakdown agglomerated particles to smaller aggregates.
There are two classes of dispersers to grind material. The first group uses a high shear disperser blade rotating at a high speed.
The second class are bead mills that use grinding media. A mechanical force moves the media at a rapid speed creating a shear force by collisions and rolling movements.
The material volume, viscosity, and final particle size are key factors to select the right disperser.
Description
BYK-Gardner offers a wide range of drawdown cards and charts for virtually any application and coating material.
Stringent quality control during the production process assures that the paint test charts have the most consistent color and gloss in the industry.
The drawdown cards are easy to use and an inexpensive substrate to test a variety of coating properties such as opacity, spreading rate, penetration behavior, and flow and leveling properties.
Drawdown charts are used to assess architectural, industrial, automotive, wood coatings, inks, and cosmetic products.
The byko-chart drawdown charts will work with solvent and water based coatings and inks.
Description
Also called grind gages and Hegman gages. Many types of solid materials must be ground or milled into finer particles for dispersion in appropiate liquid vehicles.
The physical properties of the resulting dispersions, often called “grinds”, depend not only on the actual size of the individual particles, but also on the degree to which they are dispersed.
The Fineness of Grind Gage is used to indicate the fineness of grind or the presence of coarse particles or agglomerates in a dispersion. It does not determine particle size or particle size distribution.
Grind gages are used in controlling the production, storage, and application of dispersion products produced by milling in the paint, plastic, pigment, printing ink, paper, ceramic, pharmaceutical, food, and many other industries.
Description
Hardness is the resistance of a coating to a mechanical force, such as pressure, rubbing or scratching. In practice, different testing methods are used:
Pendulum Hardness
– In accordance with methods described by König and Persoz
Indentation Hardness
– Buchholz Indentation Testers
Scratch Hardness
– Hardness Meter Dur-O-Test
– Pencil Hardness
BYK-Gardner offers instrumentation needed to perform various hardness tests.
Impact & Bend Testers
Description
The Impact Tester is a widely used device for the coating and plastic industries. In both industries impact resistance is measured by a falling weight from a controlled distance. For plastic materials the force is increased until structural failure occurs.
In the case of a coated surface, failure will appear as a crack in the paint film. The impact tester creates a deformation in the surface that can also be used to measure a coating’s flexibility. BYK-Gardner offers a wide variety of models and accessories to comply with ASTM and ISO methods related to a resistance tester.
For a coating to perform properly during use, the paint must have the proper amount of flexibility to withstand cracking under stress. A common test is bending a coated panel over a cylindrical or conical shaped bar. A mandrel bender is commonly used to test for paint flexibility.
A cupping tester is another coating flexibility tester that slowly pushes a round punch through a coated panel until cracking occurs in the paint film. The degree of bending or deformation of the coated surface is measured to assess the coating flexibility.
Paint Application
Description
Paint application onto a drawdown chart requires a highly precise coating applicator to achieve a consistant dry paint film. Coating applicators can be bar applicators or wire wound rods. BYK-Gardner offers a wide selection of applicators for many enduses.
The gap clearance and film width are important dimensions to consider when selecting a bar applicator. For wire wound rods the wet film thickness, wire diameter, and film width should be considered.
In North America wire wound bars are described as mayer rods; the single clearance bar applicators are described as a bird bar.
An automatic film applicator improves the consistency of a drawdown. When more than one operator is drawing down the same coating or ink, the dry film appearance will vary because of different drawdown techniques. Drawdown speed and pressure on the applicator tool will impact the results.
Temperature Testers
Description
The temp-gard is a temperature measurement data logger that tracks the temperature variation of a drying oven. A painted product is sent through the oven in a continuous process. The temperature data logger is sent through the oven in the same manner to profile and record the temperature changes.
The temperature profile is downloaded to the temp-chart software for a comprehensive evaluation of the oven conditions. The software determines if the paint is fully cured.
The gradient-oven is a device for evaluating the baking and curing behavior of liquid paints, powder coatings, and resins. The gradient-oven is also used for accelerated acid-etch testing for automotive coatings. A micro-processor controls 45 heating elements that are individually controlled and monitored.
A coated panel can be tested by a step gradient or linear gradient programs set-up by the user. The temperatures are precisely measured by a PT-100 probe inserted into each element.
The dew point meter records the air humidity, temperature and surface temperature of a substrate prepared for painting. The dew point meter will assess the climatic conditions to determine the suitability for painting. The dew point meter will send an audio and visual alarm when the condensation probability is high.
Viscometers
Description
BYK-Gardner offers many choices to measure the kinematic viscosity of coatings, resins, and ink. A kinematic viscometer does not apply a shear force to measure the viscosity. The most common viscometers are the flow cups that include Zahn cup, Ford Cup, ISO Cup, and DIN cup.
The bubble viscometer is also included in the kinematic viscosity category. All of these viscometers are easy to use and are reasonably priced. They are ideal for production control, field inspection, or laboratory use.
To measure the absolute viscosity a rotational viscometer is used. For non-Newtonian liquids a digital viscometer that applies a precise shear rate is needed. For laboratory viscosity measurement BYK-Gardner offers a comprehensive line of rotational viscometers.
The viscometer product line can measure viscosity from a near water-like viscosity to a very high viscosity range for epoxy, sealants, and paste. To measure viscosity under a high shear rate Cone and Plate viscometers are available. The easy to use digital Stormer viscometer is also part of the rotational viscometer family.
Wet Paint Testing
Description
BYK-Gardner offers a variety of testing instruments to evaluate physcial properties of paint & coatings in the wet stage:
- Electrical conductivity of solvent based finihes for electrostatic spray application
- Density measurement with pyknometer
- Drying time performance of paint and coatings during varying time ranges 6-12-24 hrs
- Contact angle measurement etc.
Conductivity Measurement:
Liquids build up a specific ohmic resistance to the electric current, depending on the applied voltage. The reciprocal value is the conductivity. The measured resistance depends on the geometric arrangement of the electrodes within the measuring cell. In order to be independent of the measuring cell, the measured resistance has to be divided by the cell constant “C” which yields specific resistance. The BYK LC 2 conductivity meter is for solvent-based coatings only. The conductivity test is easy to perform.
Density Check:
Density is the weight per unit volume at a specified temperature. Density determination is important measurement to convert weight into a volume unit. When coatings are manufactured the raw materials are measured in weight units to control the process. The finished product is usually sold in volume units. In accurate density volume measurement is fundamental to an efficient operation. A density cup has also been described as a liquid pycnometer. In North America a weight per gallon cup is commonly used name. An ISO cup is a popular design globally. All the density cup designs work the same way having a precisely made cup with small hole in the lid to allow for removal of excess liquid and air.
Drying Time Performance:
The various stages of drying and curing that occur in films are easy to detect, but difficult to define in terms of chemical and physical principles. Several factors such as oxidation, evaporation, and polymerization impact the drying time. Additional physical factors impact the drying time: wet film thickness, substrate, temperature, humidity, air circulation and light exposure. In order to perform an objective analysis a drying time recorder is very helpful as the drying time is under controlled conditions.
