How Is FRP Made?

A: FRP Is made in a variety of different ways depending on the product you’re making. Ours at DEFI is mainly made by the open mold process, hand layup, and the pultrusion process.

FRP is not a new invention. In fact, FRP was invented over 110 years by Leo Baekeland, an American chemist who emigrated from Belgium. Bakelite as he branded it, was the first of its kind and was revolutionary due to its unique characteristics. Fast forward to today and you can find that FRP is used across a wide array of industries. The oil industry uses FRP grating for offshore wellhead platforms. Water-parks use it for stairs, railings, slides, and even decking. Industrial warehouses like retail giants, Amazon and Uline also use FRP extensively in their warehouse designs.

The reason it’s used in so many different industries is that it’s the “swiss army knife” of structural materials. In fact, FRP is the most versatile and strongest material available for structural uses of all degrees. How does something so revolutionary come into existence? To answer that question we have to talk a bit of chemistry so you can understand the makeup of FRP.


FRP is a composite material that is comprised of plastic resin combined with thin fibers of glass known as fiberglass. When these two materials are mixed you get what is referred to as “FRP” or fiber-reinforced plastic.

The plastic resins act as a binding agent to hold together the glass fibers in the structural layer of FRP. These resins also can contain many different characteristics such as fire resistance, and anti-corrosion qualities. It all depends on the type of resin used in the production process. At DEFI our FRP is manufactured in a 3-tier layered process, these layers, called laminates are comprised of:

  • Structural Layer: The base that gives the composite its strength and structural integrity as well as a base of temperature resistance
  • The Chemical Barrier Layer (CBL): This layer gives FRP its signature chemical resistance that gives it supreme durability against corrosives
  • Topcoat (Surface Veil): Depending on the usage of the product being created, this layer gives it characteristics to stand up to the environment. It also adds an additional layer of temperature resistance.

The most compelling characteristic of this unique composite is its strength, durability, and ability to adapt to any environment. When you realize how FRP is made, it makes sense why it’s the material of choice for many different industries.


Most of our products are made using three different fabrication methods depending on the end-use. We use pultrusion, open mold process, and hand lay-up. Each process has its own unique applications. It is ideal for FRP products from DEFI to be fabricated using the process of pultrusion. Due to the nature of the pultrusion process, this method gives several advantages over other methods such as increased strength, higher corrosion resistance, and better impact resistance.


Pultrusion is a technique for creating continuous structural shapes but without distorting the cross-sections. This process involves pulling the three laminates mentioned before through a heated die that forms it to specs. We will cover this method more extensively since most of our products are created with this process.

The fiberglass reinforcement material is usually in continuous form—hollow spools, roving, or filament mats.

The resin liquid mix that is used to bind the fibers is cured within a catalytic reaction that is caused by the heat from the die. The resin then becomes rigid and takes on the shape of the die’s cavity.

The pultrusion process is used in a wide range of industries for many different applications. This is because they can duplicate the strong properties of traditional materials while correcting the weak properties. For example, pultruded fiberglass grating duplicates the strength of steel grating but is corrosion-resistant, unlike steel.

While there are several variations of the pultrusion method such as reciprocating pullers or caterpillar pullers—the concept is the same.

Pultrusion Review

  • Fiberglass is pulled through the line and covered in resin until fully saturated.
  • A surfacing veil or topcoat is added depending on the traits needed for the project.
  • After saturation, the mixture is pulled through a device that pre-forms it in preparation for the heated die. Passing through the die heats the composite and gives it a rigid profile while forming it to the die shape.
  • The newly formed structural shape is then moved on to the cutting saw, the final stage in the process.

Some circumstances will slightly alter the process such as required traits and shape requirements. However, the process remains relatively homogenous—it really boils down to the materials and end-use of the final product.

Hand Layup Open Mold Process

Hand layup is an open molding process—the oldest molding process for creating FRP products. There are no technical skills or complex machines needed. It’s ideal for low-volume, labor-intensive, larger products such as vessels, tanks, car bodies, and oil pipelines.

As the name suggests, this process is all done by hand so the quality really depends on the person’s skill in crafting FRP.

The mold contains the structural shape that is needed therefore careful order of steps must be taken. For example, to have the final product shiny or have texture, the surface finish of the mold needs to reflect that specification. If the external surface of the product needs to be smooth, you use a female mold to fabricate the product. In the same manner, if the inside specification is smooth, then you pour on the male mold. Either way, molds must be pristine or the finished product will reflect any defects in the mold itself.

Unlike pultrusion, since the resin is viscous and is being poured into the mold, it needs to have a releasing agent. Without a releasing agent, the product may not come free from the mold, rendering it unusable. Using a thin coating of wax, polyvinyl alcohol, or mylar film allows for a smooth release of the finished product after curing.


Fiber-reinforced plastic composites offer a myriad of benefits to infrastructure, oil, aviation, marine, and many other industries. The unique traits and adaptability of FRP make it ultra-compatible for a wide range of uses.

High Strength But Lightweight
FRP is one of the strongest materials available on the commercial market. Compared pound for pound against traditional materials—FRP is stronger. Because it is so tough but light, rigidity can be maximized without a significant increase in weight.

Resistance To Corrosion
Metal rusts and is vulnerable to corrosive substances such as acid, salt, and blood, but FRP is unaffected. This resistance to corrosion makes it ideal for marine oil applications and factories alike.

Temperature Resistance
FRP materials do not thermally conduct very well at all, therefore, they are perfect for extreme temperatures. The insulative quality of the composites makes it suitable for either arctic or sub-tropical regions.

Flame Resistant
FRP products can use surface veils that are designed to meet international building codes regarding flame resistance.

FRP composites are insulative by nature, therefore they do not conduct electricity. They are widely used by utility companies as power line poles, stand-offs, and other sensitive electrical environments.

Aesthetic Flexibility 
Because FRP begins as a liquid, a very wide range of aesthetic traits can be achieved such as color, textures, and shape. It is adaptable to almost any project or specialized requirements.


It doesn’t matter which industry you’re in, our products can benefit your company in so many ways. We have helped water-parks, municipalities, chemical plants, and many others with long-lasting FRP. They depend on us for safe, strong, and durable fiberglass products that will last through the toughest conditions. Contact us today to see how our products fit into your project.

Recent Post

Get Connected