Paint For Fibreglass Guide

If you are looking for guidance on paint for fibreglass look no further. Below we will discuss the best products and practices for painting fibreglass, fiberglass boat paint and other GRP suitable paints for other substrates such as roofs and cladding.

What Is GRP?

GRP is the abbreviation of Glass Reinforced Plastics. It is also known as fibreglass. Glass reinforced plastic is used for the manufacture of various product ranges. It is ideally suited for the protection against water. Therefore, GRP is used as a material for boats, roofs, Jacuzzi’s, hot tubs and anti-slip products such as grating and step edges. GRP is also used in the manufacture of vehicles, cars and machinery parts.

Some benefits of GRP include:

  • GRP is electrically non-conductive
  • It is radar/radio wave transparent
  • GRP does not corrode
  • It has a high strength to weight ratio
  • GRP provides excellent durability
  • GRP is light in weight

So now you know what GRP is, we will now discuss the best practices when it comes to painting this versatile material.

Prepare Your Fibreglass Prior To Painting

As with all painting projects the most important part of the job is the preparation. To prepare the surface for painting GRP, the surface will need thorough cleaning. Promain‘s technical team suggest the use of a degreaser such as Centrecoat R09 Heavy Duty Surface Cleaner. After a good wet clean, abrade the surface mechanically with a tool such as Indasa Electric Random Orbital Sander. For smaller areas, we would recommend the use of Indasa’s Rhynosoft Pads.

Marine Paint For Fibreglass

Promain sell a huge range of quality marine paint for fiberglass. We would recommend a high quality marine gloss for application to not only glass fibre / GRP, but also for use on wood and metal.

For areas below water, it may be beneficial to apply a coat of underwater primer such as Teamac Metaclor P149. This is a chlorinated rubber coating that includes metal particles. These metal particles act like fish scales by stopping water from penetrating the GRP. This provides extra protection against water ingress.

Why You Need A Quality Marine Paint For Fibreglass

Fibreglass boats can suffer from osmosis. Osmosis is the process by which molecules of a solvent migrate causing blistering on boat hulls. Osmosis leads to the trapping of moisture beneath the gelcoat or topcoats causing softening of paint in areas.

By using an undercoat containing metal particles, osmosis can be prevented. When these types of specialist coatings are applied, the metal particles form a shield similar to fish scales. This prevents water from being able to find a way through the coating, protecting your fibreglass boat for years to come.

Paints For Non Marine GRP Substrates

For Jacuzzi’s you would need a far more robust 2 pack coating when coating the inside. This is because of the involvement of hot water and chemicals during their use. Promain’s technical team would always suggest a polyurethane for coating the inside of Jacuzzi’s. This is as they are more colour stable than an epoxy. In our opinion the best product available as a GRP Jacuzzi paint would be Teamac P101 High Performance Marine Gloss. Due to this paint’s excellent abrasion resistivity, Promain’s technical team recently specified this product for recoating a GRP children’s play area slide.

On the other hand, if you want to paint a GRP fibreglass flat roof, application of the Teamac P101 High Performance Marine Gloss would prove to be difficult. This would be especially true if your fibreglass roof covered a large area. You should apply P101 with a mini roller – we would really recommend forgetting the knee pain and using a GRP roof paint that is sprayable.

If your glassfibre roof has a gradient of over 1 degree, so it can drain, we would recommend application of Rust-Oleum Noxyde. Noxyde is a heavy duty, waterborne, elastomeric, single pack coating that you apply via airless spray.

GRP Boat Paints Available from

We have a range of GRP boat paint products from leading marine paint manufacturers such as PPG, Jotun, Teamac, Hempel and Sherwin Williams. If you are looking into coatings for painting GRP boat items take a look at these options:

PPG Marine

If you are looking for PPG specification for glassfibre paint on boats, take a look at PPG Sigmacover 280. This primer is ideal followed with a topcoat of either PPG Sigmadur 520 or 550 to finish. These airless spray applied products provide a high performance, durable, coating that offers excellent colour and gloss retention when exposed to UV light.

Teamac Marine Gloss

Teamac Marine Gloss provides exceptional opacity with a high gloss finish. This versatile single pack glassfibre boat paint is suitable for all general marine areas including boat bridge decks and walkways, masts and marine superstructures. Teamac Marine Paint will also provide exceptional adhesive properties to metal and wood.

Owatrol Glassfibre Paint

Owatrol produce a quality range of premium marine paints. If you are just looking to revive your glassfibre paint, we would suggest the use of Owatrol Marine Polytrol. This amazing product is not a paint but will instantly revive plastic bringing it back to its vibrant colour like brand new. However, it is not suitable for application to white or pale coloured GRP. Have a look at this video showing the power of Polytrol on plastic items:


If you have any questions regarding painting glassfibre, please contact our technical team.

Interested in finding out more about the marine paints Promain has to offer? Read these articles below:

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