Gel Coating & Supplies

Polyester gel coat is a type of surface coating that is commonly used in the production of composite materials. It is a pigmented resin-based material that is either applied to the surface of a mold before the layup of the composite material or used afterward for finishing, refinishing and repair. Here are some key aspects and characteristics of polyester gel coat:

1. Surface Finish: Polyester gel coat provides a smooth and glossy surface finish to composite parts. It helps to enhance the aesthetic appearance of the final product and can be formulated to produce various colors and effects.
2. UV Resistance: One of the significant advantages of polyester gel coat is its excellent resistance to UV degradation. It acts as a protective layer, shielding the underlying composite material from the harmful effects of sunlight, such as color fading and surface degradation.
3. Chemical Resistance: Polyester gel coat exhibits good resistance to a wide range of chemicals, including acids, alkalis, and solvents. This resistance helps to maintain the integrity and appearance of the composite part when exposed to various chemical environments.
4. Impact Resistance: Polyester gel coat provides some degree of impact resistance to the surface of the composite part. It helps to prevent surface damage, such as cracking or chipping, due to impact or abrasion.
5. Adhesion to Substrate: Polyester gel coat is designed to adhere well to the substrate, typically a fiberglass or composite material. This adhesion ensures that the gel coat remains firmly attached to the surface and provides a durable protective layer.
6. Application and Curing: Polyester gel coat is typically applied by spraying or brushing onto the mold surface before the layup of the composite material. It cures through a chemical reaction, initiated by a catalyst or promoter, to form a solid and durable coating.
7. Thickness: The thickness of the gel coat layer can vary depending on the desired application and requirements. Thicker gel coat layers offer increased surface protection but may require additional time for curing.
8. Post-Treatment: Once the gel coat has cured, it may require post-treatment processes such as sanding, buffing, or polishing to achieve the desired final finish and smoothness.

Polyester gel coat is widely used in various industries, including automotive, marine, aerospace, construction, and consumer goods. It provides an attractive and protective surface finish to composite parts, enhancing their appearance, durability, and resistance to environmental factors. However, it is important to follow the guidelines for proper application, curing, and maintenance of polyester gel coat to ensure optimal results.

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 what common problems to avoid.

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