Chemical resistant coating: For extra protection against aggressive chemicals
Whether it’s cleaning products, spills, or fumes; almost all coatings will be exposed to chemicals and acids at some point. However most of these are mild, and the coating does not require a special formulation. Chemical resistant coating or acid resistant paint is designed to provide protection from the harshest of substances. They need to perform safely and consistently under punishing conditions, and so need to be highly resistant. Without proper protective coating, solvents, acids, alkalis, salts, and other substances can be absorbed by the substrate, resulting in deterioration and contamination.
The best chemical resistant coating is one that satisfies the need of the chemical, as well as the requirements of the substrate. Choosing correctly requires fully understanding both. In this article we will outline the different chemical resistant coatings options (also ‘acid resistant paint’), and provide a guide for choosing the right one as well as where to find products and contractors in New Zealand.
How to choose the most suitable chemical resistant paint/acid resistant paint
Substrates and environments which require heavy duty protection from chemicals include flooring, storage or holding tanks, pipelines, bunds, buried metal and concrete structures, treatment plants, laboratories, cooling towers, factories, machinery and equipment, just to name a few.
The range of substrates, environments, and chemicals is matched by the range of chemical resistant paints. You might need chemical tank lining, sulfuric acid resistant coatings, hydrochloric acid resistant coating, chemical resistant paint for steel or acid resistant coating for concrete. To choose the right chemical resistant coating you need to answer these 5 questions:
- Which chemical is used? Each coating has its own strengths and weaknesses. For example, some offer protection against a certain substance, but not against another. Therefore, specify exactly which chemicals are used.
- What is the concentration of the chemicals? The stronger the concentration, the more resistance the coating must offer.
- What is the intensity of the load? When the coated substrate is completely submerged in chemicals, it must be completely resistant to this.
- What is the duration of the chemical load? Permanent loading or exposure of short duration determines how long the coating must resist.
- What are any environmental factors that play a role? A cold room or an oven, inside or outside; different temperatures require different coatings.
The 4 types of chemical resistant coatings
Chemical resistant coatings are available in a wide range of formulations, suited to different applications. The main types are polyurethane, epoxy, phenolic, and fluoropolymers. The choice of coating is further complicated by extra requirements such as high abrasion resistance, or sufficient lack of friction. Below, we explain the resistance, uses and drawbacks of each type.
Resistance / resistance rate: High.
Epoxy coatings are number 1 in terms of chemical resistant properties. These coatings offer protection against acids, alkalis, solvents, corrosive liquids, fuels, fatty acids, salt or sugar solutions, chemical cleaning agents and much more.
An unprotected concrete floor can quickly deteriorate due to exposure to chemicals, especially heavily loaded industrial floors. It is important to protect the floor. In addition to use on floors, epoxy coating is also suitable for walls and various materials (metal, wood, etc.)
Epoxy is less suitable for use in rooms with strongly fluctuating temperatures (eg cold rooms). It is also less flexible as polyurethane (cracks may occur during shrinkage or expansion of the substrate). In addition, discoloration and acquisition can occur due to UV radiation.
Resistance / resistance rate: Medium.
Polyurethane coating is often the alternative to epoxy coating where more resistance to changing temperatures is required. Polyurethane is resistant to organic corrosive liquids, acids and alkalis, fuel, hydraulic oils and solvents.
Polyurethane coatings are preferred in the dairy industry where there is exposure to lactic acid and complete immersion (brine baths). Finally, the coating is also often used in exterior environments as a topcoat on epoxy because (in contrast to epoxy) polyurethane is resistant to UV radiation.
Because Polyurethane coatings are softer than epoxy variants, the coating will wear more quickly on friction. In addition, the coating is very sensitive to moisture during the application. Furthermore, the chemical resistance is slightly lower than epoxy.
3. (Low friction) Fluoropolymer-based
Resistance / resistance rate: High.
Fluoropolymers are most known for being a primary component of non stick coatings (including Xylan and Teflon). However, they also provide very high chemical resistance at high temperatures. They can withstand a maximum use temperature of 300°C. Fluoropolymers are resistant to a wide range of chemicals, including concentrated sulphuric, nitric, hydrochloric and phosphoric acids.
Normally used where a low coefficient of friction or a lubricious surface is required. Suitable for use on concrete or metal in secondary containment linings, acid plants, fertiliser plants, oil refineries, and more.
Fluoropolymers have poor weather protection characteristics, and cannot withstand acetone, esters, ketones, and acetic acid.
4. Phenol resin-based
Resistance / resistance rate: Very high.
A phenolic coating is one in which a phenolic resin is used to cure an epoxy. Therefore, it is actually a reinforced epoxy coating. This type resists 98% sulfuric acid, hydrochloric acid, transmission fluid, gasoline, formaldehyde, phenol and a variety of other chemicals. The coating performs better at higher temperatures than polyurethanes and unprocessed epoxies.
This type of coating is often used as a protective layer in and on tanks , pipes, immersion baths for most acids, solvents and salts (chemical storage).
Not recommended for exposure to some strong organic acids and solvents. Note: the less epoxy has been used as an ingredient in the coating formula, the less resistant it is to chemicals.
Buy chemical resistant coating: products and prices in New Zealand
With so many different environments and substrates that require a chemically resistant coating, it is no surprise that the range of available products and services has expanded over the years. The above described coatings are available, but there are also specially formulated coatings. On the other hand, coatings based on fluoropolymers or phenol resin are not suitable for self-application. That is why we give below examples of a number of coatings with an epoxy base that are for sale in the New Zealand. In many cases, however, customization is necessary. Feel free to contact us for a solution tailored to your specific requirements.
|Chemical Resistant Coating Type||Chemical Resistant Coating Product||Product Suitability||Price|
|Two component epoxy||GemCoat Epoxy Industrial Floor Coating||Factory floors, dairy sheds, changing rooms, toilet & shower blocks||$368.00 (8 Litre kit)|
|Solvent free epoxy coating||GemCoat Epoxy Coating||Concrete, steel, and fiberglass tanks, and secondary containment (bunds) exposed to immersion and splash & spillage of chemicals.||$345.00 (3 Litre kit)|
|Two component epoxy matrix coating||GemCoat CR 1||Formulated to have resistance to most concentrated acids & alkalais, and many other commonly used chemicals||$230 (2 Litre kit)|
Find Chemical resistant coating specialists in Christchurch and around New Zealand
Applying chemical resistant coating for complex projects requires expertise. Not only in the application phase but also in the advisory phase. An experienced specialist will gladly inform you about the most suitable coating for your project. Below is a selection of specialists in New Zealand.
|CHEMICAL RESISTANT COATING CONTRACTOR||Address||Specialization|
|GMR Holmac Ltd||406 Pickering Road RD3, Tamahere, Hamilton 3283||Chemically resistant lining systems|
|EC Flooring Contractors||PO Box 880, Manly, Whangaparaoa||Chemical resistant flooring|
|Blake Surfacings Ltd||Belfast Business Park, 55 Belfast Road, Belfast, Christchurch 8051||Specialized acid and caustic resistant floor coatings|