is acrylic paint flammable

Is Acrylic Paint Flammable? (Enamel, Porcelain, Lacquer)

The durability and ease of use of acrylic paint make it an ideal choice for a wide variety of applications. These may include painting the interior or exterior of your home, your vehicle, or even smaller hobby projects. Your choice of paint may depend on your project’s exposure to heat, so is acrylic paint flammable?

Your typical water-based latex acrylic paint is not flammable in its liquid state, some solvent-based acrylic mixes like lacquers and enamels are highly flammable. When dry, acrylic latex paint is a polymer that can burn at very high temperatures.

To determine if some variant of acrylic paint is right for your project, you will need to know the limits of each type of acrylic paint. This article will cover the hazardous material standards used to define flammability as well as the differences between acrylic paints.

Flash Point and Flammability Rating

It is necessary to discuss the different safety standards to help clear up any confusion over the flammability of acrylic paints. It is essential to understand the rules since there are various safety standards for determining flammability. A material may qualify as flammable by one standard while it is not by another.

The United States Hazardous Materials Identification System (HMIS) uses a flammability scale from 0 to 4 with 0 being non-flammable. The lowest level of flammability, 1, is defined as having a flash point of over 200°F. Liquids at this low level of flammability would require preheating before they will ignite (source).

On the other hand, the U.S. Occupational Safety and Health Administration (OSHA) defines a flammable liquid as “having a flash point at or below 199.4°F (93°C).” By this standard, anything with a higher flash point is not flammable, even though some materials will burn at higher flashpoints (source).

Canada’s Workplace Hazardous Materials Information System (WHMIS) distinguishes between flammable materials and combustible materials. Combustible liquids have a flash point over 100°F (37.8°C) but under 200°F (93.3°C), while flammable materials have a flash point less than 100°F (37.8°C) (source).

Similar to the OSHA and WHMIS standards, the National Fire Protection Association (NFPA 704) defines flammability as having a flash point over 200°F. A typical Material Safety Data Sheet lists a flammability rating for the material in both HMIS and NFPA.

Flash point vs. Autoignition Temperature

The flash point of a substance is the lowest temperature at which the fumes of that substance will ignite when exposed to a flame or other source of ignition. While the vapors may ignite, there may not be enough fumes to sustain combustion.

The Autoignition temperature is the lowest temperature at which a substance will spontaneously combust under normal atmospheric conditions without a source of ignition.

The Flammability Rating of Acrylic

Acrylics are chemical compounds that contain the acryloyl group derived from acrylic acid. Acrylic acid is flammable with a flash point of 124°F (51.11°C) and an autoignition temperature of 820°F (437.78°C) (source).

Acrylate monomers derived from acrylic acid, such as methyl methylene, are used to make polymers, such as acrylic. Acrylic is also known as polymethyl methacrylate (PMMA). Acrylic resin is the crucial ingredient in acrylic paint as a binder that holds the pigment of the paint to the desired surface.

The Flammability of Plexiglas

On its own, acrylic is flammable, burning at 560°F (293.33°C)(source). PMMA has a flash point over 482°F (250°C) and autoignition temperature of 580°F (304.44°C) (source). With such a high flash point, and even though it will burn, acrylic is not considered flammable by either the OSHA or WHMIS standards.

Plexiglas, consisting of acrylic, becomes pliable at 260°F (126.67°C) and burns at 560°F (source). The autoignition temperature of plexiglass is the same as acrylic acid at 820°F. The combustibility of Plexiglas is one reason that it’s not legal to use for the windows of on-road vehicles (source).

Acrylic Latex

Acrylic latex paint was developed by Dow Chemical, which produced Plexiglas and other acrylic products for the war effort during World War II. As the war was coming to a close, they needed to find a new market for their acrylic products (source).

They developed acrylic latex paint just in time to take advantage of the housing boom of the 1950s. The low flammability and milder fumes of latex compared to the ordinary oil-based paints of the time made latex an attractive option.

The Composition of Acrylic Paint

A laboratory where beakers and vials are shown for testing the composition of paints such as acryclic.
The chemistry behind acrylic is fascinating.

Latex paint is a term that encompasses any paint that uses a synthetic polymer like acrylic, styrene acrylic, or vinyl acrylic. The same type of paint is called an emulsion in the United Kingdom. Since acrylic is repelled by water, other chemicals like emulsifiers are required to facilitate its mixture with water.

The offset acrylic’s hydrophobic (water-repelling) properties, surfactants are introduced that contain molecules that are hydrophobic on one side and hydrophilic (water-loving) on the other. Surfactants like sodium dodecyl sulfate lower the surface tension of acrylic, allowing it to disperse in water.

Paints are composed of pigment, binder, extender, solvent, and other additives. In the case of acrylic, the solvent is usually water, acrylic resin serves as the binder, while the surfactants are additives (source).

The technology for water-based acrylic emulsions was developed by Otto Rohm and Otto Haas in the 1940s, just as the war was coming to an end. By 1953, they had their first acrylic emulsion on the market, a binder called Rhoplex AC-33.

The Flammability Rating of Acrylic Latex

A typical Material Safety Data Sheet for water-based acrylic latex paint, lists both the HMIS and NFPA flammability rating as 0 (source). While in its liquid state, water-based acrylic latex paint is not flammable.

However, as emulsion paints dry, the water evaporates, and the paint forms a hard polymer film. While not flammable in its liquid state, latex is flammable according to HMIS standards when in this hard polymer form.

Dried acrylic paint will burn somewhere around 560°F, which is the burning temperature of the acrylic resin.

In addition to the acrylic itself, other ingredients in the paint contribute to its flammability. The extenders help to slow the drying time of paint, and many of these are glycerin-based. Like acrylic, glycerin is mildly flammable with an HMIS rating of 1.

The emulsifiers or surfactants like sodium dodecyl sulfate are highly flammable with an HMIS and NFPA rating of 3 (source). These do not evaporate when the paint dries.

According to the U.S. Consumer Product Safety Commission, some solvent-based acrylic paints contain other flammable substances like “turpentine, xylene, toluene, and methyl ethel ketone” (source).

The Advantages of Acrylic Latex

The flexibility of latex paint makes it ideal for areas of the home that experience regular changes in temperature, such as the bathroom or kitchen. As the wood expands or contracts, so does the paint, reducing the risk of cracking and flaking.

Acrylic latex paints and enamels also dry much faster than oil-based paints. While oil-based paints might be easier to clean, they also tend to yellow over time.

Compared to oil-based paints, acrylic paints give off milder fumes and are less toxic. Of course, they still contain harmful chemicals.

Acrylic latex can be toxic if it has metallic pigments like mercury (vermillion), cadmium (cadmium yellow), chromium (chrome yellow), or lead (reds, whites, and yellows). Some water-based paints also contain trace amounts of formaldehyde or ammonia (source).

House Paints vs. Artist’s Acrylics

A series of wet paintbrushes is shown in this file photo.
House paint or artist paint?

Latex paints have a chalky texture due to the massive amounts of calcium carbonate used in comparison to artists’ paints. They also use a white base, while an artist’s tube paints will have pure pigment mixed with a clear resin (source).

The quality of acrylic tube paint is directly related to its viscosity or “body.” Heavy-body paints have the most pigment, and professional-grade paints are heavy-bodied. Student-grade paints have a medium body, while craft-grade paints have a soft body, low viscosity, and less pigment.

Artist’s acrylics are also more lightfast, resistant to fading due to light exposure, and durable than house paints. There are no expectations that house paints last as long as the artist’s paints since walls will need to be repainted after a few years anyway. House paints tend to be much less lightfast and can fade slightly over time.

Most artist’s acrylics do not even list an HMIS or NFPA rating, and painter’s acrylics, watercolors, or acrylic gouaches, are considered as nonhazardous for transport on aircraft according to TSA regulations. However, some of these paints do have an HMIS flammability rating of 1.

DecoArt Americana acrylic latex paints are medium body paints frequently used on small craft projects, and they do have an HMIS flammability rating of 1 (source).

Acrylic paints for model kits sold under such brands as Testors or Tamiya. Rustoleum owns Testors, and their Model Master acrylic paint has an HMIS flammability rating of 1 and a flash point of 201.2°F (94°C) (source). {INSERT TESTORSPIC}

Acrylic Pouring

Acrylic pouring is a form of abstract fluid art where some artists use a butane torch. In acrylic pouring, the artist uses soft-body acrylics or liquid acrylics with a high flow rate. They place the paint in cups and then pour it onto a canvas.

Sometimes the cups are filled with a single color, and other times the containers are filled with more than one color and a medium to keep them from mixing. Since acrylic paint is non-flammable in this highly fluid form, the artist can carefully use a torch to lower surface tension before the pour or dry sections of paint after the pour.

Acrylic Enamel

When Acrylic enamel dries, it produces a smooth and glossy surface. It also forms a hard surface that is more resistant to weathering. Water-based acrylic enamels will dry on the outside first within an hour, but they can take weeks to cure on the inside thoroughly.

Interior acrylic latex enamels are for a high gloss finish on floors. Water-based acrylic enamel is not flammable by NFPA standards, but it does have an HMIS flammability rating of 1 and a flash point of 201°F (source).

Acrylic Urethane Enamel

Acrylic enamel is an automotive paint, to this day, but acrylic urethane enamel paint is now the leading paint used by the automotive industry. Acrylic urethane enamels combine acrylic and polyurethane and are highly toxic.

Acrylic urethane is also highly flammable, with an HMIS flammability rating of 3 and a flash point of 75°F (23.89°C) (source). While some automotive paints are compatible with a self-etching primer, epoxy primers are the preferred type of acrylic urethane.

Acrylic urethane enamel is also used for refinishing sinks and bathtubs made of porcelain or cast iron. Regular latex paint will simply flake off over time. The process may cost around $350 to $500, but that’s better than spending thousands on replacing your bathtub altogether (source).

Due to the toxicity of acrylic urethane, the bathtub or sink might require removal and transport to a workshop. If done onsite, the area will require proper sealing off, and the user will need appropriate protective equipment, including a respirator.

Aerosol-Based Acrylics

Aerosol cans, to apply many types of acrylic enamel, as well as the aerosol-based paints themselves, are highly flammable. A typical aerosol can of acrylic enamel has an HMIS flammability rating of 4 (source).

Porcelain

Porcelain enamels should not be confused with regular enamel paints. Porcelain enamels are vitreous, glass-like, enamels. The fabrication is powdered glass, fused onto the material at high temperatures over 1380°F (748.89°F).

If you attempt to fire a piece of porcelain with acrylic paint on it, the paint is going to burn. Instead, you can brush on or spray on an acrylic coating after firing the piece. There are food-safe paints like Porcelain 150 specially designed for use on dinnerware.

Porcelain 150 is a water-based paint that allows for application to ceramics, glass, or metal. After applying the paint and allowing it to dry over 24 hours, you can bake a porcelain plate in your home oven at 300°F for 35 minutes.

Acrylic Lacquer

Acrylic lacquers have a faster drying time than acrylic enamels, and they produce an even harder, durable surface. The downside to lacquer paints is that they are highly flammable and toxic. Automotive and wood furniture finishes are the most common use.

An acrylic lacquer base coat has a high HMIS flammability rating of 3 (source). Rustoleum automotive clear coat acrylic lacquer is also highly flammable at 4, and it has a flash point under 20°F (-6.67°C) (source).

Acrylic urethane enamel paint has largely superseded lacquers in the automotive industry for both base coat and topcoat. It is due to the environmental concerns over lacquers, which are highly prone to evaporation during the painting process.

Heat-Resistant and High-Temperature Paints

A black, painted wood stove is shown in this file photo.
A stove is painted with heat-resistant paint that can withstand high temperatures.

While acrylic paint does have a high flash point and low flammability, it is not well-suited for high-temperature situations. For example, you would not want to use acrylic paint on your grill or oven. The paint will eventually dry out and crack, potentially getting flakes of paint in your food.

Instead, special heat-resistant paints are available for use on furnaces, fireplaces, ovens, grills, chimneys, engine components, etc. While not all manufacturers disclose the polymers they use in their paints, most of the high-temperature and heat-resistant paints have some level of heat-resistant silicone resin.

Some of these do contain a combination base of silicone resin and acrylic resin, while others advertise as silicone-ceramic based.

While non-flammable, when dry, these paints can be highly flammable in their liquid form because of the solvents they use, like acetone. Once those solvents have evaporated, and the paint has cured, the paint is highly heat-resistant.

Intertherm 875 has a mix of silicone and acrylic resin, intended for use on steel with operating temperatures as high as 500°F (260°C) (source).

Other high-temperature paint brands designed for automotive use on engines and exhaust systems, like U.S. Paint or POR-15, can withstand temperatures up to 1200°F (648.89°C). Stove Bright and other paints designed for the use of painting stoves and ovens have the same temperature rating up to 1200°F.

VHT® Flameproof™ coating advertised for use on exhaust systems, engine headers, and piston domes with the ability to withstand heat up to 2000°F (1093.33°C) (source). It has a silicone-ceramic base with an acetone solvent (source).

Thurmalox® 240 is another silicone-ceramic based paint designed for high temperatures. They’re designed to protect metal surfaces at temperatures ranging from 1100°F to 1400°F (593°C to 760°C) while also resisting corrosion (source).

In its liquid form, Thurmolox® 240 has a flammability rating of 3 and a flash point of 102.2°F to 221°F (39°F to 105°C) (source). VHT® Flameproof™ coating has a flammability rating of 4 and a flashpoint of – 20.2°F (-29°C) in aerosol form (source).

Final Thoughts

For most acrylic paint applications, flammability will not be a significant concern. It is due to water-based acrylic latex house paints having an HMIS flammability rating of 0. Some artist’s acrylics may have a negligible rating of 1, while some acrylic enamels and lacquers can have a score as high as 3 or 4.

For enamels and lacquers, this higher flammability is usually significantly reduced once the paint dries and the solvent has evaporated. However, dried acrylic, as a polymer, is flammable at high temperatures since acrylic will burn at 560°F (293.33°C).

If you’re considering an application that involves temperatures over 500°F (260°C), several high-temperature paint alternatives are better suited to that purpose.

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