They say that “necessity is the mother of invention.” This is true in coatings, not only in formulation but also in testing. Products are developed to fill a need, but how do you know you have achieved the properties required if tests for those key performance indicators don’t exist?
As an established example, we have elastomeric coatings. The first acrylic-based resins for roof coatings were formulated into paints around 1975. These resins were somewhat similar to ones used in caulks, at least in their flexibility, adhesion, water and weather resistance. As more and more paint companies developed products, it became very difficult for architects, specifiers and contractors to distinguish among acrylic roof coating products.1
In 1995, under the Roofing and Waterproofing Committee, D08 developed ASTM D6083, which is entitled “Standard Specification for Liquid Applied Acrylic Coating Used In Roofing.” Most of the tests cited as part of the standard exist from other standards. However, some were developed, in that there wasn’t any way to evaluate specific properties, such as adhesion to various substrates. The ASTM D6083 specification employs either the ASTM C794 or D903 method for measuring peel adhesion, which was the result of a lot of laboratory work in the Springhouse facility of Rohm & Haas.
More recently, many new products and testing have been developed in tandem, to differentiate improvements to the products. Several cases are provided herein, citing ASTM standards. In most cases, there are similar standardized tests from DIN, SAE and other governing bodies.
Scratch-resistant coatings for optical wear have been available for many years. Prior to their development, there had been many tests for resistance to chipping, scratching, etc. including ASTM D-0968-05, D4060-10, D6037-96 and others. These are all too harsh for plastics such as polycarbonate, polymethylmethacrylate, CR-39™and Trivex™, as well as coatings on plastics. Hence, several tests were developed, which include the Bayer Abrasion test (ASTM F735-81)2, Steel Wool Abrasion and others3. Instruments to qualitatively measure the reduction in optical clarity (haze) were developed along with the test methods.4
Recently, fingerprint transfer resistance has become a much-desired property for electronic devices with screens, as well as for appliances, where stainless steel and glossy black finishes have become popular. Again, to evaluate performance, one must have a reliable, reproducible and quantitative test method. Daikin America has developed a test method to evaluate the resistance to fingerprint transfer.
As indicated in Optool DSX literature,5 the fingerprint is transferred and then a Kimwipe is used with a standard force, to test ease-of-removal.
With the proliferation of wind turbines came the realization that the leading egde of the blades experienced erosion similarly to those on fixed wing and rotary aircraft. However, unlike the latter which can be addressed relatively easily, onshore blades that are 45M long, attached to a turbine’s hub 80M off the ground, are very difficult to overhaul. In addition, downtime taking that unit out of service results in lost power and revenue. There are existing rain erosion tests that have been used for aircraft, but no test is available to evaluate ice accretion and shedding, which are additional issues with wind turbine blades.
There are several laboaratories that have since developed test methods and equipment to appraise ice accretion and release from coatings systems. The United States Corp of Army Engineers runs the Cold Regions Research and Engineering Laboratory (CRREL).
The aluminum cylinders are spray-coated with material, and then the coated cylinders are frozen into an ice mold. The sample is placed in a fixture and a load applied, so the failure stress (kPa) can be measured. Although a good test, there is a fair amount of variability and therefore reproducibility is a challenge.
Fraunhofer Institute (IFAM) has developed an Icing Chamber to simulate the conditions of freezing rain or mist in sub-zero temperatures.
The Chamber mimics most conditions which include frost adhesion, ice-rain and runback ice test, where the ice moves along the blade as it is formed. It can test ice accretion, as well as cyclical melting and reformation of ice. Their system also utilizes Dynamin Differential Calorimetry to investigate the freezing point depression caused by funtional surfaces. Through the use of these new test methods, patents have been developed based on quantiative data collected during development.6
There are other examples of tests and equipment developed to evaluate coatings formulations in new markets. Dry time for fast-dry traffic paints is just one additional one. Many new ASTM tests have been developed for new products, applications and markets, as well as solventborne coatings, but have been deemed inappropriate for their waterborne counterparts.
In summary, all of the tests cited were developed as a result of a need to quantify performance to differentiate changes in formulations. They almost always mirror an actual condition that exists, but in a way that is reproducible, can be performed in a laboratory setting, and in a much shorter time frame than occurs naturally.
Further reading:
- The Current Spin on Wind Turbine Coatings
- Specialty Coatings: Protecting Against Electromagnetic Emissions
- Setting Up a Lab – Scenarios for Success, Part 1
- Setting Up a Lab – Scenarios for Success, Part 2
References:
- RCI Interface: ASTM D-6083: What It Says, What It Means, How It Came to Be [PDF]
- Taber Industries: Bayer Abrasion Test
- Vision Care Product News: Comparing Scratch-Resistance Tests
- Vanlandingham, Mark. (2018). Scratch and Mar Resistance of Polymeric Materials
- Daikin America: OPTOOL DSX Technical Data Sheet [PDF]
- USPTO #20170306177; Polyurethane-based protective coatings for rotor blades, 3M, October 26, 2017
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Interesting. Hi, we are the Nano Polycom Paint Co S.A. Poland. At this moment not active, but we have severa paints that are truly interesting, as: Paint you apply and dry down to -20 degrees C, Paint you apply under water (anti corrosion) and on roof (can be applied during rain), that then dries as “normal” paint, and then you can give a 15 year written rust proof guarantee (if no mechanical harm dune to coating). Paint can be applied on grease. Moves this substance up on top of paint. Made a demo of this at the lab of Tikkurila OY in Helsinki (painted on butter) and the lab staff did not believe what they witnessed (we discussed a cooperation at that moment – that´s why these tests were performed, as an illustration of our products). We have paint that puts out fire, or warns for low oxygen levels in cargo holds, or this other one that protects aluminum constructions up to +2.500 degrees C. We also have paint using solar energy for giving away light or heat. All paints being patented. All these paints have been tested using well know lab technology. I am mentioning all this since they are new paints, not seen on the market before. New test methods needed ?
I would suggest that if these are truly new paint (systems) and they possess properties that can’t be tested by current DIN, ASTM, SAE, etc. tests, that you may need to develop methods, preferably through/with an ISO-certified lab. Good luck
Abrasion testers determine rub resistance in a short time by rubbing the surface of materials in an accelerating speed, such as fabrics, leather, rubber, paper, metals, paints, etc. https://www.testextextile.com/sale/by-category/abrasion-pilling-snagging/
Thanks for adding some additional information. I didn’t include textiles, since the article appears in the Paint & Coatings section.
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