Fiberglass Reinforced Plastic (FRP) is a versatile composite material made of glass fibers embedded in a plastic resin. Known for its lightweight yet durable properties, FRP is commonly used for constructing storage tanks, pipes, ducts, cladding, and other industrial applications. While the smooth finish of FRP offers an aesthetic appeal, painting FRP can further enhance its visual appearance and protect it from weathering. This article provides a comprehensive guide on painting FRP, from understanding its composition to application techniques and maintenance.
What is FRP?
Fiberglass Reinforced Plastic, as the name suggests, is made by reinforcing plastic resin with glass fibers. The glass fibers come in various forms like woven fabrics, mats, veils, and rovings. They provide strength and rigidity to the plastic resin which coats over them. Some of the common resins used include polyester, vinylester, epoxy, and phenolic.
FRP offers exceptional durability, flexibility, corrosion resistance, and thermal insulation. It is also extremely lightweight compared to metals. These properties make FRP a popular choice for manufacturing chemical tanks and pipes, boat hulls, automotive bodies, aerospace components, and building facades. FRP products can be molded into almost any shape.
Properties and Applications of FRP
Here are some of the notable properties and typical applications of FRP:
- High strength-to-weight ratio – With strength comparable to metals but almost 80% lighter, FRP is widely used in weight-sensitive applications like aircraft and spacecraft.
- Corrosion resistance – FRP can withstand harsh weather elements and does not rust or degrade like metals. Ideal for outdoor equipment and chemical/industrial tanks.
- Electrical and thermal insulation – The non-conductive nature of FRP makes it suitable to house electrical wiring. It also provides thermal insulation.
- Impact resistance – FRP panels absorb shock and impact better than glass panels. Useful in high traffic areas.
- Design flexibility – FRP can be molded into complex and custom shapes. Often used for decorative cladding and facades.
- Low maintenance – Requires very little maintenance compared to wood or metals. The smooth surface can be easily washed.
- Fire retardancy – FRP is inherently fire-retardant depending on the resin used. It can act as a barrier to slow fire spread.
Some common applications of FRP include:
- Storage tanks and pipes
- Boat and vehicle bodies
- Roofing and skylight panels
- Water park rides and pools
- Traffic light housings
- Playground slides and structures
- Wall/ceiling panels and architectural shapes
Preparing FRP for Painting
Painting FRP requires some preparation to ensure proper adhesion and performance of the paint. Here are the key steps:
The glossy smooth surface of FRP needs to be lightly abraded to create some texture for the paint to cling onto. This is done through scuff sanding using 120-220 grit sandpaper. The sanding removes the gloss and exposes fresh FRP material underneath. Avoid completely stripping off the gel coat layer.
After sanding, the FRP must be thoroughly cleaned to remove all dust, oils, mold release agents, and other contaminants. A commercial grade degreaser should be used, followed by a rinse with clean water. Allow the surface to completely dry before priming or painting.
Applying a primer coat is highly recommended before painting FRP. The primer fills in any pores in the fiberglass and provides a uniform surface for the paint to adhere to. Epoxy or urethane-based primers specially formulated for plastics work very well on FRP. The primers should be compatible with the chosen paint.
Choosing the Right Paint
When selecting paint for FRP, consider the exposure conditions, desired finish, and compatibility with primer. Here are some good options:
Epoxy paints are highly recommended for FRP, especially for outdoor use. They contain a tough epoxy resin binder and provide excellent adhesion to fiberglass. Epoxy paints are resistant to abrasion, chemicals, and weathering – ideal for boats, tanks, and outdoor FRP structures. They come in high gloss or satin finishes.
Acrylic Latex Paint
For indoor FRP surfaces not exposed to weathering, acrylic latex paints can be used. They are easy to apply, allow good vapor transmission, and come in various sheen levels. Acrylic latex paints are quite affordable and provide good UV resistance for indoor use.
Polyurethane paints contain a durable polymer resin that cures into a hard, glossy finish. They are extremely resistant to abrasion, moisture, and chemicals – suitable for high traffic areas. Polyurethane paints require a primer and provide a lasting, protective finish.
Factors for Paint Selection
Consider the following factors when choosing paint for FRP:
- Exposure to sunlight – Use epoxy or polyurethane paint for UV resistance
- Exposure to water/chemicals – Epoxy or polyurethane paints provide the best protection
- Accessibility for retouching – Latex paints allow for easier touch-ups
- Abrasion/traffic resistance – Epoxy and polyurethane paints are most durable
- VOC emissions – Water-based acrylic latex paints have lower VOCs
- Compatibility with primer – Consult manufacturer recommendations
- Color options – Epoxy has limited colors, while latex and polyurethane offer more choices
Application Techniques and Tips
Follow these best practices when painting FRP:
- Lightly scuff-sand using 120-220 grit sandpaper to dull the gelcoat layer
- Clean thoroughly with a degreaser to remove contaminants
- Rinse off debris using clean water and allow to fully dry
- Apply primer coat compatible with the paint as per manufacturer’s instructions
- Allow recommended drying time before painting over primer
- Stir the paint well before using and check for proper consistency
- Apply two coats of paint using brush, roller, or airless sprayer
- Use overlapping strokes to ensure even coverage and appearance
- Allow sufficient drying time between coats as specified by manufacturer
- Allow paint to dry completely before use or contact
- Epoxy paints may take 24-48 hours to fully cure and reach hardness
- Do not expose to water or chemicals until fully cured
- Improper prep can cause poor adhesion – thoroughly scuff-sand and clean the FRP
- Applying paint too thick can cause drips and sagging – use multiple thin coats
- Orange-peel texture indicates improper roller or brush technique – roll/brush smoothly
- Fish-eye effect means contaminants are present – clean and degrease the surface
- Blushing occurs if painting in high humidity – avoid painting in moist conditions
Enhancing Appearance and Durability
Painting FRP can drastically improve its visual appeal while also enhancing durability:
- FRP can appear hazy – painting provides color and masks the translucent effect
- Any color can be achieved, unlike gelcoat which has limited color choices
- Different textures can also be attained depending on paint and application technique
- Paint forms a protective barrier against UV rays, water, and chemical exposure
- Prevents weathering, discoloration, and degradation over time
- Can allow FRP to withstand prolonged outdoor exposure
- Paint opens up endless possibilities for custom graphics, patterns, lettering etc.
- Specialty paints like chalkboard or magnetic paints allow functional customization
- Painting over FRP enables creating unique facades and decorative effects
Maintaining Painted FRP
To maximize the lifespan of painted FRP, follow these maintenance practices:
- Use a mild detergent and soft sponge or cloth for routine cleaning
- Avoid abrasive brushes or high-pressure washing which can damage the paint
- Rinse off any cleaning agents thoroughly after washing
- Periodically inspect the painted surface for any chips, cracks or damage
- Touch up defects immediately to prevent moisture penetration
- Use touch-up paint in small quantities to quickly repair any damaged areas
- When re-coating larger areas, lightly sand and apply fresh primer before painting
- Over time, complete repainting may be needed to restore appearance
- Lightly sand to degloss, clean, re-prime and repaint using the original coating system
Case Studies and Examples
FRP Playground Slides
An amusement park coated their fiberglass playground slides with a two-part polyurethane paint system. The high-gloss vibrant paint transformed the look of the slides while also protecting them
Refurbishing FRP Building Facade
An office building constructed in the 1980s used FRP panels for its exterior facade. Over time, the sun and weather caused the panels to appear faded and yellowed. Rather than replacing the panels, the building owners had them sanded, primed with epoxy primer, and repainted using a semi-gloss acrylic latex paint. The paint refreshed the look of the building and provided UV protection.
Custom Painted FRP Gasoline Truck Tank
A company that transported gasoline needed to paint the FRP tanks on their truck fleet. After proper surface prep, the tanks were coated with a specialized fuel-resistant epoxy paint. To differentiate their brand, the company had an abstract pattern incorporated using automotive grade polyurethane paints. This allowed them to customize the look in their corporate colors.
FRP Bathroom Wall Panels
To liven up the ambiance of their bathroom, a homeowner painted the factory-finish white FRP wall panels using a semi-gloss water-based acrylic enamel paint. The painted sky blue panels complemented the look of the ceramic tiles and helped conceal the seams between panels. The acrylic paint provided a scrubbable and stain-resistant finish.
Painted FRP Door Skin
A plain fiberglass entry door was given an artistic makeover by painting over the molded FRP door skin after proper sanding and cleaning. Sponge painting techniques were used with exterior grade acrylic latex paints to create a visually textured door that resembled a reclaimed wood plank surface. The paint added curb appeal and completely transformed the look.
Black Painted FRP Column Wraps
A hotel lobby was retrofitted with decorative FRP wraps around the existing support columns. To make the columns recede, the FRP wraps were painted black using a flexible epoxy enamel paint. The dramatic glossy black columns contrasted well against the lighter marble walls and helped highlight the lobby’s interior design elements.
FRP Pallet Rack End Caps
The end caps on industrial pallet racks in a warehouse were constructed of molded FRP. To help reflect light and brighten the storage aisles, the charcoal gray end caps were sanded smooth and painted white using a premium acrylic latex paint. The painted end caps really helped improve visibility and reflectance inside the previously dark warehouse.
What is the best paint for FRP?
For outdoor FRP applications, high-performance two-part epoxy paints are the best choice. They provide superior adhesion, abrasion resistance, and protection against UV rays, water, and chemicals. Epoxy paints resist chalking or cracking over time. For indoor FRP surfaces, acrylic latex or polyurethane paints also work very well.
When selecting paint, consider the exposure conditions, desired gloss level, and compatibility with primer. Consult with paint manufacturers to choose coatings specifically formulated for FRP substrates. Proper surface preparation and priming is crucial for paint longevity on FRP.
How do you paint over FRP?
Follow these steps to properly paint over FRP surfaces:
- Lightly sand the surface using 120-220 grit sandpaper to dull and roughen the gelcoat layer. This improves paint adhesion.
- Clean the FRP thoroughly with a degreasing agent to remove mold release agents and surface contaminants.
- Rinse off any residue and allow surface to fully dry before painting.
- Apply a compatible primer coat formulated for plastics as per manufacturer’s directions.
- Allow primer to dry completely before painting. Lightly sand if re-coating after 24 hours.
- Stir the paint well before applying using a brush, roller or spray. Apply two thin coats for best results.
- Allow proper drying time between coats based on the paint specifications.
- Allow paint to fully cure before exposing to water or chemicals. Cure time differs for each paint type.
Proper surface preparation, priming, paint selection, and application technique ensures paint longevity and performance on FRP substrates.
Can fiberglass board be painted?
Yes, fiberglass board, also known as fiberglass reinforced plastic (FRP) board, can be painted. The same painting principles and preparation methods apply for FRP board as with other fiberglass products. Here are some tips for painting fiberglass board:
- Lightly sand the board using 120-grit sandpaper to create a surface profile for paint adhesion.
- Clean thoroughly with a degreaser and rinse well. Allow to fully dry.
- Apply a specialized plastic primer before painting for best results.
- Epoxy and acrylic latex paints are good options for fiberglass board.
- Apply using a brush, roller or airless spray. Allow proper drying time between coats.
- For outdoor use, select paints with UV inhibitors that resist chalking and fading.
- Water-based acrylic latex paint works well for indoor fiberglass board applications.
Following proper surface prep, priming, and paint application techniques allows transforming the appearance of fiberglass boards through painting. The paint provides an added protective barrier for improved durability.
How do you whiten FRP panels?
Here are some methods to whiten or brighten the appearance of FRP panels:
- Sand the panels lightly and apply a white epoxy or acrylic paint. Multiple coats may be needed for full opacity.
- For a more temporary whitening, use a FRP gelcoat restore or polishing compound. This helps remove oxidation and yellowing.
- Bleach cleaning solutions can also help brighten FRP panel surfaces. Ensure proper ventilation when using bleach products.
- Replace or overlay the existing panels with new white FRP panels for a consistent white appearance.
- Apply a fresh layer of white gelcoat resin by spray or brush. Adhere per the resin manufacturer’s guidelines.
- Aggressive mechanical sanding or grinding can strip away discolored layers but may impact strength. Use caution.
Proper prep work, priming, and using white paints or gelcoat resins offers the longest-lasting solution for whitening weathered FRP panels. Always test products on a small hidden area first. Seek professional contractors for more extensive FRP renewal or resurfacing needs.
Painting over FRP enables dramatically enhancing its appearance while also providing protection from UV exposure, weathering, and wear-and-tear. With proper surface prep, primer selection, and application technique, FRP can be painted using epoxy, acrylic, polyurethane, and other coatings suitable for plastics. Paint allows customizing the look of FRP along with options for graphics and special finishes. Periodic maintenance of painted FRP helps retain the aesthetic appeal and extends service life. Using the recommendations in this guide, FRP installations can be refreshed and enhanced through the power of paint.