Industrial and protective coating
Q #1: What are the criteria to select the best industrial and protective coating?
A #1: To select the best protective coating for industrial applications, you must first establish your criteria and their order of importance. The following provide a general idea on the main differences of coatings provided by Azmeh Co. and help in selecting the best finish for your project. A- Industrial air drying alkyd coatings are excellent choice for mild conditions where cost is a consideration. Hammertone coatings (Hammer Finish) does not require a primer, they are applied directly to metal (DTM) and can help reduce (but not eliminate) costly metal preparation operations in addition to providing an attractive finish. B- In general, for moderate or severe weather and industrial conditions, a rust inhibiting primer followed by an epoxy or polyurethane topcoat will provide superior protection. C- Epoxy coatings provide excellent adhesion and corrosion protection. D- Polyurethane coatings provide outstanding gloss and color retention, abrasion, chemical and abrasion resistance. E- Chorinated rubber coatings are excellent for exterior industrial applications where high flexibility and excellent humidity, water and salt water, chemical, abrasion, and weathering resistance are required. F- Silicone resin coating (THR) provide high heat and weather resistance. Azmeh Co. provides a suggested solution for each specific application (Refer to the Table Summary of the suggested solution systems according to the required application). Notes: § Severe conditions include one or more of the following extreme conditions: - High mechanical wears and repeated cleaning with industrial agents. - Immersion in water, waste water, sea water and chemicals such as acids, alkalis, salt solutions, organic solvents, etc. - Coastal situation area of high industrial pollution and areas close to chemical processing plants. § Moderate conditions are found in outdoor exposure to heavy rainfall and continuos humidity in light industrial and urban conditions and rural areas. § Mild conditions are experienced in interiors subject to condensation or where there is source of pollution. § Very mild exposure conditions are found in warm and dry interiors.
Q #2: What is Industrial air-Drying Alkyd Coatings?
A #2: Industrial air-drying alkyd coatings are commonly used as protective coatings in a variety of industries. Through modifications of the alkyd resin with drying oils and other resins, alkyd products provide versatility in performance requirements and are used in finishing a wide spectrum of manufactured products. Alkyd coatings are used as primers (with anticorrosive pigments such as Iron Oxide, Zinc Chromate, Zinc Phosphate, and Red Lead), mid-coats, and topcoats. They are applied on steel structures and anywhere exposed to moderate humidity and industrial environments. Alkyd coatings can also be used as mid/topcoat for epoxy primers. They are an economical choice for quick drying, indoor maintenance, exterior maintenance, rust prevention, gloss and color retention. Different industrial alkyd coatings are provided by Azmeh Co. under the trade name SYN and more specifically SYN203 Red metal primer, SYN210 Red lead primer, SYN205, and other coatings such as SHR, Hammer finish, etc.
Q #3: What does mean 2k coating?
A #3: In general, a 2k coating is made by reacting, on-site, just before application two components ("base" with a "hardener or curing agent") in a certain mixing ratio. A chemical reaction occurs between the two parts.
Q #4: Should I respect the mixing ratio given in the Technical Data Sheet for 2k coatings? And how much mixing time is required?
A #4: Absolutely, respecting mixing ratio is the key to a thorough cure, good films, strong bonds, and excellent chemical and mechanical properties. 2 to 3 minutes of mixing using a SLOW SPEED MIXER are required, swiping the sides and bottom of the container is recommended.
Q #5: What is the potlife (working time) of 2k coatings based on base and hardener or catalyst?
A #5: After the two parts are combined there is a working time (pot life) during which the material can be applied or used. Generally the pot life will be anywhere from minutes to one hour or longer. At the end of the potlife the mixture becomes very warm and quickly begins to harden.
Q #6: What are the major pitfalls that most users fall into when applying 2 K coatings?
A #6: Bad mixing practices are the cause of almost all problems. Coating can fail for lot of other reasons such as bad surface preparation.
Q #7: What does the term "urethane" mean? And what are the different types provided by Azmeh Co.?
A #7: The term urethane and polyurethane apply to certain types of binders used for coatings and clear coatings. The urethane polymer is also called polyurethane. There are different types of urethane systems provided by Azmeh Co.: a- One-component urethane-alkyd OD Lacquer; this is the usual "polyurethane" varnish used in residential and commercial applications on bare or stained wood (floors, furniture, doors, etc.); b- One-component, reacts and crosslinks upon application and exposure to moisture from the air; known as "moisture cure urethane" they are highly resistant to chemical and mechanical attack (PU1K lacquer). c- Two-component, a polymer "base" mixed at time of use with a "catalyst or hardener"; has short pot life, requires fairly exacting mixing proportions. · Urethane-alkyd, SYN205 + drier 205, recommended for industrial use, furniture, trucks, vehicles,…etc. Provides a smooth, uniform, tough, and durable surface for metal and wooden surfaces. · Two component polyurethane coatings (sealer, coat, lacquer), available at Azmeh Co. under the trade name PU MDF. They are easily applied on wooden surfaces to provide highly flexible wood finishes. · Acrylic-urethane are used as a clear coat or as a topcoat in a variety of industries such as automotive (ST and LAC2k Clearcoat), power plants, oil, gas and marine industries, offshore structures etc (HardTop). These coatings are more resistant to fading from sunlight than epoxies.
Q #8: What are the benefits of urethane-alkyd coatings?
A #8: Urethane-alkyd coatings offer greater toughness and abrasion resistance than do unmodified alkyds and they are superior to conventional alkyds when applied to surfaces that are intermittently exposed to light chemical environments. They are designed for interior or exterior application on metal, wood or concrete surfaces. They are preferred to other polyurethane with respect to the cost/performance ratio.
Q #9: What are the benefits of acrylic-urethane coatings?
A #9: Acrylic-urethane coatings are generally considered high performance coatings, offering excellent gloss, color and gloss retention, and excellent chemical resistance, solvent resistance and outstanding durability, weathering characteristics, superior UV and acid-etch resistance. It’s this durability that makes them ideal for end markets where protection is of great importance. Urethane coating requires an epoxy primer coat as they do not bond as well as epoxies. While polyurethane coatings tend to feature a higher initial cost, their outstanding performance and durability make them highly cost effective over their life cycle.”
Q #10: Where polyurethane coatings are in general used?
A #10: Polyurethane coatings are used in the transportation industry for coating everything from trucks to trains. They are also widely used for clear coats by the automotive industry and for coating power plants, oil, gas and marine industries, and offshore structures and also for coating furniture and wood floors. Their use has increased because of their excellent performance properties, including weatherability, flexibility, wear resistance and chemical resistance.
Q #11: What are the advantages of Silicone resin?
A #11: The main advantage of silicone resins is that they have excellent resistance to climatic effects such as UV light, humidity and heat resistance. These high-priced resins are used as heat-resistant coatings for exterior applications on steel structures where thermal resistance is required such as furnace and hot pipe exteriors, heat exchangers, incinerators, mufflers, engines, exhaust and other exterior elevated steel surface temperature. The Silicone resin (THR) provided by Azmeh Co. for industrial use can withstand high temperatures up to 600° C. A 20-30 ?m layer ensures a good protection.
Q #12: How to check for Hardness of a coating?
A #12: To quickly check for full hardness use the Rule of "Thumb". Press thumbnail into solid or coating firmly; no indentation should occur. This test is helpful to determine if a coated surface is ready for sanding.
Q #13: What is epoxy and what agents are in?
A #13: In general terms, an epoxy polymer is made by reacting, on-site, just before application two components (epoxide group base with a hardener curing agent) in a certain mixing ratio. A chemical reaction occurs between the two parts generating heat and hardening the mixture into an inert, tough and hard.
Q #14: Why use epoxy coatings?
A #14: Epoxies are noted for their excellent adhesion, are widely used as primers and finishes in applications requiring extreme corrosion resistance. Their main disadvantage is poor resistance to ultraviolet radiation, which results in poor color and gloss retention. Since they resist moderate heat, epoxies find many uses in electrical apparatus as decorative coatings as well as electrical insulation. Epoxies provide heavy-duty performance for challenging environments and tough industrial applications. They are known for their excellent water, chemical, and abrasion resistance, excellent durability, low porosity and strong bond strength. They are also excellent for floors, walls, harsh processing environments tank lining, etc.
Q #15: What are the major differences in epoxy coatings?
A #15: Some epoxy coatings are two component solvent borne or high solid or solvent free; some are two-component water-based; some are one-package products, and some are coal tar modified (black color). Other differences come from the curing agent or "Hardener". Epoxy coatings provided by Azmeh Co. using CAT10, CAT11 and CAT70 as curing agent (hardener) are reasonably resistant to corrosion, whereas with hardener CAT20, CAT21, CAT30 and CAT40 have high resistance to chemicals. Epoxy coatings with CAT30 are recommended for food contact. Epoxies have good adhesion on a variety of substrates such as metal, wood, concrete, glass and pottery. Epoxy primers, due to the presence of the anticorrosive pigments such as Zinc Phosphate, Zinc Chromate and Zinc Dust, show excellent anticorrosive properties. These coatings are applied on offshore and steel structures, pipelines, machinery, etc. Epoxies are compatible with a wide range of primers, mid and topcoats. However, a system including epoxy primer and epoxy topcoat ensures good performance and shows reasonable resistance to severe atmospheric condition.
Q #16: What is the curing temperature of epoxy coatings provided by Azmeh Co.?
A #16: Generally epoxies become too thick and cure too slowly when be applied at temperatures below 10°C. Temperatures between 15 to 30°C are best. After the epoxy has fully cured, it can handle temperatures well below -20°C.
Q #17: How mixed quantity, container shape and temperature will affect curing time of epoxy coatings?
A #17: Mixed Quantity A larger quantity of mixed epoxy will create more heat and have a shorter open (working) time and overall cure time. Smaller batches of epoxy create less heat than larger batches and also have longer working and cure times. In other words, a thicker layer of epoxy will cure sooner than a thin layer. Container Shape The mixture s heat can be distributed by pouring the mixture into a larger, flatter container (like a roller pan, for example.) This also extends the open time. Temperature Heat can be applied to shorten open and cure times.
Q #18: What color is the basic epoxy resin?
A #18: The basic epoxy resin provided by Azmeh Co. is EPX05 that is yellow and chalk in direct sunlight (UV). For pigmented epoxies select colors that are dark or contain a lot of yellow (such as green).
Q #19: How to protect the epoxy from weathering in direct sun light?
A #19: Epoxy surfaces should be protected from sun exposure in order to retain their color and attractive gloss. A polyurethane topcoat (HardTop) may protect epoxy coatings from weathering in direct sunlight. Indoor epoxy coated pieces do not need a protective topcoat.
Q #20: What is the effect of temperature on potlife, cure time and viscosity of epoxy coatings?
A #20: In general, a temperature change of 10°C will double or half the potlife and cure time of an epoxy. Higher temperatures will lower the viscosity but also reduce the working time for applying epoxy.
Q #21: When can I sand epoxy coatings?
A #21: Epoxies require minutes or hours to harden, but complete hardening will generally take 7 days. Most epoxies will be suitably hard within a day, but may require 48 hours to harden before the coating can be sanded.
Q #22: How to check for Hardness of a coating?
A #22: To quickly check for full hardness use the Rule of "Thumb". Press thumbnail into solid or coating firmly; no indentation should occur. This test is helpful to determine if a coated surface is ready for sanding.
Q #23: What is the temperature resistance of epoxy coatings provided by Azmeh Co.?
A #23: Epoxy coatings provided by Azmeh Co. resist continuos working temperature up to 60°C and down to -20°C.
Q #24: What is the recoat time for epoxy coatings?
A #24: The recoat time is the time that the surface is still tacky. If more than 30 hours pass between coats, we recommend a light scuff sand. Always check for blush on surfaces. The best time to recoat epoxy is within about 48 hours after the initial coat forming therefore a simple mechanical bond.
Q #25: How thick should epoxy coating be?
A #25: Epoxy primers should have a thickness of about 40 to 80 microns, while epoxy topcoat should have for moderate exposure conditions a thickness of about 80 to 120 microns. For severe exposure conditions a total dry film thickness (DFT) of 300 microns is considered a fairly thick industrial coating.
Q #26: What is BLUSH of epoxy coatings, and how do I remove it?
A #26: Blush is a waxy film that forms in the surface of the curing epoxy. On contact with high humidity or water, this coating turns into an opaque white smudge that turns into dry chalky powder with time. When blush is very bad, it is a visible white film, otherwise it might not be visible, but still there. Most epoxies blush to some degree but some do not "especially moisture tolerant epoxy". Blush may form over fast mixed hardener and resin. Slow mixing prevent blush formation. Blush needs to be washed off from the surface of the epoxy before it can be recoated. Blush can be removed with warm water and a sponge (rinse and wipe) and will not leave without some abrasive scrubbing (after the epoxy is completely cured). Blush free epoxies allow additional coats and bonding without prior sanding!
Q #27: In some cases, after applying epoxy coating, I realize that fish eyes appear on the coating surface. How to avoid fish eyes appearance?
A #27: Fisheyes are areas on a coated surface where the coating literally pulls away leaving a coatingless void or fisheye on the substrate. Often fisheyes are caused by surface contaminants such as dust, wax, oil or other contamination. Good surface preparation prevents fisheye appearance.
Q #28: Are epoxy coatings suitable to be applied on galvanized steel or Aluminum?
A #28: Galvanization is itself a protective coating. If galvanized surfaces must be coated epoxy primers may adhere to it, but we recommend using an approved primer (WP) prior to applying epoxy coatings. Aluminum substrates should also be primed by WP as a tie coat prior to applying epoxy coating in order to ensure better adhesion.
Q #29: What type of lining system or product should I consider, for storage tank, pipes, etc.?
A #29: High solid epoxy (EPX13, EPX16 and EPX33), solvent free epoxy (EPX36), High solid coal tar epoxy (EPX14 and EPX24), water base coal tar epoxy (EPX19 and EPX09), and solvent free coal tar epoxy (EPX04) are the most used products provided by Azmeh Co. (Refer to the Table Summary of suggested application solution systems).
