Polyester resins are commonly used in the composites industry as a matrix material for fiber-reinforced plastics. These resins are relatively inexpensive and easy to process, making them a popular choice for a wide range of applications, including boat building, automotive parts, and construction materials. They can also be used in the making of solid surface materials and laminates, and for coating and finishing applications. The resins are typically combined with fibers such as glass, carbon, or aramid to create strong, lightweight, and durable composite materials.

Polyester resins can be used to make a variety of products, including:

  1. Fiberglass reinforced plastics (FRP) - commonly used in boat building, tanks, pipes, and other structures.
  2. Automotive parts - such as body panels, spoilers, and other exterior parts.
  3. Marine applications - polyester resins are widely used in the marine industry for manufacturing boats, yachts, and other watercraft. They provide excellent resistance to water and UV degradation, making them suitable for various marine environments.
  4. Corrosion-resistant equipment: Polyester resins can be formulated to exhibit exceptional resistance to corrosion, making them ideal for manufacturing corrosion-resistant tanks, pipes, and other equipment used in chemical processing plants and industrial settings.
  5. Electrical and electronic components: Polyester resins with electrical insulation properties are used in the production of electrical and electronic components such as insulators, circuit boards, and encapsulation materials for electronic devices.
  6. Construction materials - including roofing, siding, and window frames.
  7. Solid surface materials - used for countertops, sinks, and shower pans.
  8. Laminates - used for flooring, wall coverings, and furniture.
  9. Coating and finishing - for wood, metal, and other surfaces.
  10. Sports and recreational equipment: Polyester resins find use in the production of various sports and recreational equipment, including surfboards, skateboards, snowboards, and lightweight helmets. Their high strength-to-weight ratio is advantageous for these applications.
  11. Artistic and Industrial Design - for sculpture and other artistic expression, and for industrial molds and prototypes.
  12. Adhesive and sealant - for bonding and sealing different types of materials.

These are some of the common uses of polyester resins but there are many others as well, depending on the specific properties of the resin and the application.

Premium polyester gel coats deliver superior cosmetics and durability for parts and molds.

Polyester gel coats are a polyester resin that are commonly used as a surface coating in the composites industry. The strengths of polyester gel coat include:

  1. Durability: Gel coats are extremely durable and resistant to UV light and weathering, which makes them suitable for outdoor applications.
  2. Chemical resistance: Gel coats have good resistance to a wide range of chemicals, including acids, alkalis, and solvents.
  3. Aesthetics: Gel coats can be pigmented to create a wide range of colors and finishes, and they can be polished to a high gloss.
  4. Good mechanical properties: Gel coats have good impact resistance, which makes them suitable for applications where the surface may be subject to impacts.
  5. Easy to apply: Gel coats are easy to apply and can be sprayed, brushed, or rolled on the surface.
  6. Cost-effective: Polyester gel coats are relatively inexpensive compared to other coating options, making them an affordable option for many applications.
  7. Versatile: Polyester gel coats can be used in different types of composite products such as boats, tanks, pipes, and other structures, solid surface materials, laminates, and many other applications
  8. Good adhesion: Gel coats have good adhesion to the substrate, which helps to keep the composite structure together.

In addition to their strengths, it is important to note some considerations when using polyester gel coats:

  1. Curing process: Polyester gel coats require a curing process to harden and achieve their full properties. This typically involves the use of a catalyst or initiator, such as peroxide, which initiates the cross-linking reaction. The curing process can be affected by temperature, humidity, and the presence of inhibitors or accelerators.
  2. Thickness limitations: Polyester gel coats are typically applied in thin layers, ranging from 0.3 to 0.5 mm (0.012 to 0.020 inches) in thickness. Applying thicker layers can lead to curing issues, such as incomplete curing or excessive heat buildup, which can cause distortion or surface defects.
  3. Susceptible to damage: While polyester gel coats are durable, they can be susceptible to scratching, chipping, and cracking under heavy impacts or sharp objects. However, repairs can be made by sanding, polishing, or applying a new gel coat layer.
  4. Limited heat resistance: Polyester gel coats have limited heat resistance compared to other resin systems. They can soften and degrade at high temperatures, typically around 70-80°C (158-176°F). This can cause blistering, distortion, or color changes in the gel coat surface.
  5. Surface preparation: To ensure good adhesion and a high-quality finish, proper surface preparation is essential. This typically involves cleaning, sanding, and applying a suitable primer or mold release agent before applying the gel coat.
  6. Environmental considerations: Polyester gel coats contain volatile organic compounds (VOCs) that can be released during application and curing. While we offer LOW VOC gel coats, it is important to follow proper safety measures, such as working in a well-ventilated area and using appropriate personal protective equipment.

Overall, polyester gel coats offer a range of benefits and are widely used in the composites industry for their durability, chemical resistance, and aesthetic qualities. However, it is important to consider their limitations and application-specific requirements when choosing them for a particular project.

Choose from traditional gel coats such as white, neutral, and clear, and orange or black tooling gel coats. All our gel coats resist UV degradation and water absorption. To learn more about gel coat please visit our Learning Center articles "Gel Coat Application Guide" and "Gel Coat Troubleshooting Guide".

Shop our selection of polyester resins, gel coats, spray guns, and supplies below!

  • Styrene Thinner

    General Purpose Styrene
    5 star rating
    Styrene is the recommended thinner when using polyester and vinyl ester resins and gel coats. All polyester and...
  • Styrene Wax

    Get a Complete Cure for Polyester Resins
    4.5 star rating
    Add Styrene Wax to non-waxed polyester resin and gel coat to prevent the prolonged tackiness associated with thin...
  • Non-Skid Rubber Additive

    Safe for Gel Coats and Paint
    5 star rating
    Fibre Glast's Non-Skid Rubber Additives are ideal for creating a durable, safe, non-skid surfaces. These...
  • Gel Coat Thickness Gauge

    Simple, Precise Measure for Gel Coat Thickness
    5 star rating
    Our gel coat thickness gauge is the perfect tool for measuring wet mil thickness as you apply your gel coat. It...
    Shop Now >
  • 1 Liter High-Pressure Gel Coat Spray Gun

    The Capacity and Customization Needed For Any Project
    5 star rating
    The #134-A 1 Liter High Pressure Gel Coat Spray Gun is ideal for larger repairs and small to medium projects, with a...
  • 0.6 Liter Gel Coat Touch-Up Spray Gun

    Customize your Spray Pattern for Heavy-Duty Jobs
    5 star rating
    Not every spray application is the same. Why not have one gun that allows you to adjust spray width and volume? Our...
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  • Gel Coat Cup Gun

    Efficient & Affordable: Unique Gel Coat Spray Gun
    3.5 star rating
    You no longer have to invest in high-cost catalyst injector systems to produce high-quality parts. This unique Gel...
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  • Acetone

    Industry Standard for Dissolving Resin
    5 star rating
    Acetone is a powerful solvent, used in the composite industry as the standard for cleaning and degreasing. It will...
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#77 Polyester Molding Resin is a wax-free, general purpose fiberglass resin. This resin is a great choice for building low-cost molds, or for general fiberglass part fabrication. #90 Isophthalic Polyester Resin is a durable, dimensionally stable, corrosion resistant resin. The 225°F service temperature and low shrinkage properties of this resin are ideal for making dimensionally stable molds and extremely durable parts.

Want to learn more about Polyester Resins? Fibre Glast has a free Learning Center with helpful white papers, including: About Resins, Mold Construction, Molding Fiberglass, and Fundamentals of Fiberglass. You can also compare Polyester Resin with Epoxy Resin and Vinyl Ester Resin in the Fibre Glast blog article, Choosing the Right Resin.

Proper gel coat application can be a challenge for professionals and is probably the most common problem area for those new to composite work. Save yourself some wasted time and material. Before starting your gel coat project, read through the Gel Coat Troubleshooting Guide in our free online Learning Center, to learn the common problems to avoid.

You can place your order right here on our website or, if you have any questions, call 1.800.838.8984 | 8 a.m. - 5 p.m. ET Mon-Fri.

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