Understanding Common Coating Terms
As a leading coating manufacturer in North America, it’s easy for us to forget that everyone doesn’t understand all the terminology that has become second nature to us. Part of our mission is to be one of the most transparent coatings companies out there and to do that we have to demystify the words that we use. Admittedly, some of these terms are self-explanatory but others are not.
From product types to spread ratios, tensile strength to adhesions, we have come up with a handy explanation of all the terms you will commonly find in data sheets not just for the Weatherskin family of products, but words that are found in data sheets for coating companies around the world.
: Although the brand may carry separate installation + labor warranties for the product installers, the product warranty is different. This manufacture’s warranty ensures the product is free of defects, and for some products, the manufacturer will also warranty the products performance for a period of time as well when used for its intended application.
: This refers to the core chemistry of the coatings. Acrylic, bitumen, asphalt, polymer, rubber, silicone, are all common examples of various product types.
: The colors the product is available in.
: The different textures the product is available in.
: This term refers to the mass the product retains after going from wet to dry (curing). The closer to 100% solids, the better. Not only does measuring the thickness of your coat become easier, because you know your wet and dry film thickness will be the exact same, but less biproducts are separating from the chemistry and into the atmosphere during curing. Not all biproducts like vapors are harmful, however. Many products loose simple water mass during curing. Others do however emit volatile, potentially dangerous toxins.
: A description of what the coating or product smells like.
: This term references the different tools or equipment you would use to properly apply the coatings. Common tools are trowels, paint brushes, paint rollers. Common equipment are paint sprayers, spray hoppers, and plural sprayers. If a sprayer is used, you will commonly find the recommended psi and spray tips listed.
Minimum Coating Thickness
: This refers to the coatings thickness that is required to ensure proper performance and warranty. You may see different thicknesses listed for different coats. Different coats may be commonly called prime-coat, base-coat, inter-coat, top-coat, and for some products broadcast coats. The thickness may also reference WFT and DFT. WFT refers to wet film thickness, and DFT is dry film thickness. As most products shrink or loose mass during curing, these numbers may or may not differ substantially. The units of measurement most common are fractions of an inch (1/32”for example) or another fraction of an inch is mils (1/1000th of an inch). “60 mils WFT” is a common example of A waterproof coatings minimum thickness. You may also see products listed in millimeters, 60 mils for example is 1.524 mm.
Spread Ratio or Rate
: This is an important number. It tells you how far a product goes on its intended surface, usually per gallon or liter. Again, this number many vary depending on the coat. Thicker coats do not go as far. Also, porous substrates can absorb a lot of material, so in some applications the prime coat may be the one that does not go as far as others. An example of coverage would be “50 sq. Ft/gallon.” All too often, people price jobs by the gallon cost, where the more effective way is to price a job by the square foot cost.
: Sometimes you will be given only the minimum temperature, but most times you are provided a safe range to keep your product stored. The data sheet may also warn to keep away from things like heat, water or direct sun.
: If you touch your finger on the product, there should not be liquid transference. The products outer layer now offers some protection already against potential hazardous elements like weather.
: This will give you a safe minimum time to wait before re-coating, like 2 hours for instance, and most products give you a maximum time to wait between coats as well, like under 72 hours. Also know as your re-coat window.
: This is the time it takes for a product to be completely done adjusting to its new atmospheric conditions, and full drying & adhesion will have occurred. Generally, you do not want to disturb a coating or even interact with it until the full cure has been achieved.
Minimum / Maximum Application Temp
: This will be displayed in either Celsius, Fahrenheit, or both. This is always a good statistic to check if you’re applying the product in very low or very hot climates, as both an unwanted product ignition at high temperatures or product freezing & subsequent failure at low temperatures can occur outside the listed temperature thresholds.
Minimum / Maximum Operating Temp
: This is the minimum and maximum temperature threshold in which the product will perform as desired. Beyond these temperatures, the chemistry undergoes a state change, which can make it brittle, soft, loose adhesion, crack, or peel. Make sure to reference this temperature window, and that it matches your regular local weather if you plan on having warranty support.
: Volatile organic compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and enter the surrounding air, a trait known as volatility. Breathing VOCs can irritate the eyes, nose and throat, can cause difficulty breathing and nausea, and can damage the central nervous system as well as other organs. Some VOCs can cause cancer. Not all VOCs have all these health effects, though many have several. Most building codes or green building projects will have thresholds on the amount of VOC’s a product can contain to meet certain environmental, health and safety standards.
: Data sheets will often list items from their performance test reports. These reports have usually have internationally recognized testing processes, which means that they often use standardized lingo that are then used in data sheets throughout the coatings industry. The terms below as a sampling of some of the tests that testing companies complete on coatings.
: This is the elasticity / stretchability of the product. It will be represented as a percentage. If a product has 200% elongation, this means you can stretch it to twice it is size before failure occurs. An important aspect to note, is that not all products return to there original shape when this stretching occurs. Keep an eye on what thickness is listed as well. If no thickness is mentioned, it is likely the elongation of the product at the full minimum thickness of the product. The coating may also list a single coat thickness as the test sample.
: This test determines the amount of force needed to separate a piece of cured coating material once it already has a small cut or “knick” on the perimeter as a starting point. You are then measuring the difficulty in force required to extend the cut and rip the sample into 2 pieces. In the real-world application, this will determine how likely a failure in the material will “travel” or expand and affect the overall coating.
: This test determines the amount of force needed to separate a sample by pulling the coatings apart end to end eventually causing a failure point or breaking point in the material. This is often confused with the Tear Strength test above.
: The basic test involves a coated test sample being fully or partially immersed in water, at ambient conditions or at elevated temperatures and pressures. The coated samples are then assessed for any signs of degradation, including blistering, cracking, and adhesion loss.
: If a coating is being applied to a flexible sheeting material, like an asphalt board, or membrane sheeting, or shingle, it is desirable to know how much movement of the substrate (folding and curling) can the entire system (building material + coating) can endure without before the adhesion of the coating is compromised. This testing is often done at multiple temperatures expected to be experienced in real world applications.
: There is a term commonly used in marketing that is “self healing” applying a coating will somehow re-grow where the nail has passed through it and become a monolithic entity again. The problem is this is not what happens with any product known to the market. If you refer to the tear strength test, you will find that lots of materials, even in just the process of expanding and contracting will be compromised and begin to rip at any point of puncture. The labs measure the “self sealing” ability of the coating. If the coating is thick enough, and has good enough elongation properties, tear strength, and adhesion, then the puncture should not become larger then the item penetrating the coating, and the material that has been displaced by the penetrating item (a nail) should bunch up around the item creating a seal. This penetration should not continue to worsen over time and become a deficiency. So, if you ever hear the term self healing used, you can correct the individual and tell them the proper terminology is self sealing.
: In the paint and coating industries, paint adhesion testing is often used to determine if the paint or coating will adhere properly to the substrates to which they are applied. This is extremely important. Although lots of coatings claim to be extremely versatile on many substrates, very few have been tested for adhesion on more than 1 or 2. There are several different tests to measure the resistance of paints and coatings from substrates: The two most common being the:
Scrape Adhesion Test
The scrape adhesion test measures the determination of the adhesion of organic coatings when applied to smooth, flat panel surfaces. It is helpful in giving relative ratings for a number of coated panels showing significant differences in adhesion. The materials being tested are applied at uniform thickness to flat panels, mainly some sort of sheet metal. When the materials have dried the adhesion is determined by pressing panels under a rounded stylus that is loaded with increasing amounts of weight until the coating is removed from the substrate surface.
The adhesion of a coating or several coated sample of any paint product is measured by assessing the minimum tensile stress needed to detach or rupture the coating perpendicular to the substrate. Unlike the other methods, this method maximizes the tensile stress, therefore results may not be comparable to the others. The test is done by securing loading fixtures (dollies) perpendicular to the surface of a coating with an adhesive. Then the testing apparatus is attached to the loading fixture and is then aligned to apply tension perpendicular to the test surface. The force that is applied gradually increases and is monitored until a plug of coating is detached, or a previously specified value is reached.