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What Is Intumescent Paint?
When you’re responsible for a fire management strategy, every choice matters. One step you can take to add fire resistance to your facility is using intumescent paint.
But what is intumescent paint, exactly?
Intumescent paint or intumescent coatings help passively increase a building’s resistance to fire. When exposed to extreme temperatures, these coatings expand. The coatings lose density as they expand; as a result, they act as an insulator.
The secret behind these coatings lies in their chemical makeup. An intumescent coating consists of many chemicals, all suspended in a binder. The binder softens in response to heat exposure, letting the suspended chemicals react. These chemicals produce a foam, which hardens into an insulating material called “char.”
Intumescent Paint vs. Cementitious Paint
Intumescent coating is one of three major choices for passive fire protection. The other categories in this field are dense concrete and lightweight cementitious fireproofing. Keep reading to understand the difference between intumescent and cementitious paint.
Lightweight cementitious coatings are cement-based products used to fireproof structures. Like intumescent paint, these coatings can stand up to very hot temperatures. As their name implies, they are much lighter than dense concrete.
That said, cementitious coatings have some notable drawbacks. One major problem – space between the substrate and the coating will develop over time. That space can become filled with moisture, encouraging corrosion. As a result, these coatings can end up weakening the substrate.
Cementitious coatings also have high costs of installation and a tendency to crack. Because of these issues, cementitious coatings have lost popularity over time. Instead, intumescent fireproofing has become the go-to option for passive fire protection today.
How Much Does Intumescent Paint Cost?
There’s both a short answer and a long answer to this question, but we’ll start with the long answer. Intumescent paint costs for your project can vary based on many factors. These factors include:
- Coating thickness
- Required surface preparation
- Environmental resistance
- Expansion ratio (that is, how much a coating expands when exposed to high temperatures)
- VOC levels
With all that in mind, you can expect to pay anywhere from $4 to $12 per square foot of intumescent paint. The exact amount you’ll pay will depend on the factors listed above, among others. Still, it should be somewhere in that ballpark.
Need to brush up on your industrial coating basics? Check out our complete guide here.
Intumescent Paint Fire Ratings
There are lots of fire ratings out there, but which intumescent paint fire rating should you focus on? Two fire ratings are important to know about for intumescent fireproofing: ASTM E84 and ASTM E119.
One important intumescent paint fire rating is American Society for Testing and Materials (ASTM) Test Method E-84, or “ASTM E84” for short. This rating focuses on a material’s flame-spread.
In ASTM E84 tests, a 20-inch by 25-foot material sample is installed on a test chamber’s ceiling. Testers then apply a gas flame to one end of the sample. The results of this test determine the material’s flame spread rating (FSR) on a scale of 0-200. Inorganic reinforced cement board has a rating of zero on this scale, while red oak has a rating of 100.
From there, materials fall into three classes. Class A materials have FSRs of 0-25, Class B materials have FSRs of 26-75, and Class C materials have FSRs of 76-200.
While ASTM E84 deals with flame-spread, ASTM E119 is all about how long a material can deal with fire. For intumescent paint, “2 hour rating” and phrases like it may refer to this test.
For ASTM E119 testing, a material sample is exposed to a temperature-controlled fire. This test measures the reliability of structural elements like:
- Bearing walls
- Protective membranes
If the material/assembly in question meets various requirements, the test is successful. For more information on this test – and a video of the procedure – follow the link above.
Intumescent Paint For Steel
Summary: This Carboline product is a solvent-based intumescent paint that protects interior structural steel. It’s well-suited for use with interior steel beams, pipes, and columns.
- Durable, dust-free surface
- Good-looking smooth finish
- Compliant with VOC requirements
Fire rating: Up to four hours, depending on the structure users apply it to.
Summary: From Sherwin-Williams’ Firetex brand, this intumescent coating is a water-based option. It’s great for exposed structural steel in interior settings.
- Paint-like finish
- Resistant to impact
- Applies well to substrates
Fire rating: Up to two hours fire protection.
Summary: PPG’s STEELGUARD line helps protect steel substrates from cellulosic fires. This coating is a one-component, solvent-borne coating created with structural steelwork in mind.
- Apply on-site or off-site
- Weather-resistant for up to a year
- Matte finish
Fire rating: Up to 150 minutes cellulosic fire protection.
Intumescent Paint For Wood
Summary: Flame Seal Products, Inc., a company specializing in fire-resistant coatings, sells this coating. It has a lower activation temperature than other intumescent paints – use it with wood or plastic.
- Clear coating
- Safe to handle
- Easy to apply
Fire rating: Provides Class A or Class B protection when applied correctly.
Summary: A Shield Industries, Inc. product, this water-based coating can protect a wide variety of substrates. The materials it’s compatible with include wood, steel, and many others.
- Low VOC levels
- Durable, decorative finish
- Thin film coating
Fire rating: Tested to various fire resistance standards. Up to two hours fire protection when applied to a heavy steel column.
Summary: International Fireproof Technology, Inc. sells intumescent paints that can help boost your structure’s fire resistance rating. This water-based intumescent coating is especially suited for use with wood and gypsum.
- Apply with spray, roll, or brush
- Non-toxic and hypoallergenic
- Flat finish
Fire rating: Provides Class A fire protection in accordance with ASTM E84. Can protect combustible substrates from fire for up to 30 minutes.
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