A: Absolutely FRP can be painted. There are going to be several steps that need to take place to prep the product you’re going to paint. You’ll need to grind the product down to the fiberglass strands so the paint has something to adhere to. Once that is done you can paint the fiberglass all different kinds of colors that you wish.
Why Would You Want To Paint FRP?
Unfinished/coated FRP, depending on the resin you use, can be susceptible to sun damage from UV rays or water incursion. This of course only is referring to FRP products that are used outdoors as indoor products are not exposed. Epoxy resins degrade and lose strength over time in direct sunlight due to fiber blooming. Polyesters can give way to water incursion, and vinyl esters, while stronger than polyester resins, are weaker than epoxy.
When water infiltrates FRP it can cause bubbling or blistering beneath the surface, although this takes decades to happen. However, it should be noted that once blistering begins to show up, eventually it will lead to delamination of the composite. This can cause a serious problem and you have probably seen the signs of it most often on abandoned fiberglass boats. Epoxy is the most susceptible to this delamination due to UV exposure. Over time, the composite will crumble which leads to major safety concerns.
No Reason To Worry—FRP Is Still Strong
FRP is a more superior and durable solution than traditional metal or wood for outdoor and indoor use. FRP can be further protected against UV damage and water incursion using industrial coatings or paints. When we say paints, we aren’t talking about any regular off the shelf can of paint. We mean industrial coatings that serve a purpose beyond aesthetics. In the FRP industry, these coatings are applied during the finishing process. For purposes of this discussion, we’ll refer to these coatings as “paints.”
Industrial FRP Paints
Painting FRP adds a barrier against UV light as well as water, both fresh and ocean varieties. Not only does the paint protect the FRP but it also looks appealing and can come in a variety of colors. It can be painted both during the manufacturing process as well as later for maintenance.
As mentioned before, you can’t just expect to use any type of paint for your outdoor FRP product. There are two main types of paint we will cover. It should be noted that there isn’t any paint in existence that will offer perfect protection. You must examine the pros and cons of each type as well as the environment your FRP product is being exposed to.
In addition to the two different paint types suitable for FRP, there is also the factor of application technique. Either paint can be applied with the techniques discussed as the two are not mutually exclusive. It all depends on which combination of paint and application works best for your needs.
The Two Most Suitable Paints For Use On FRP
You already know that FRP is short for fiber-reinforced plastic. However, did you know that due to its makeup, not all paint will properly protect against UV and water incursion? Acrylic paint, for example, is fine for FRP products used indoors with no special needs. However, when exposed to UV light, acrylic paint provides little protection. The two categories of paint most suitable for outdoor use on FRP are polymer-based—epoxy and polyester.
Epoxy and Polyester Based Paints
Both of these paints are made from plastics but polyester-based paint just needs air to cure and comes in a one-part solution. On the other hand, epoxy paint needs a catalyst, temperature, and air for curing. Epoxy comes in two parts in separate containers of equal volume, or sometimes slightly different volumes.
Since both categories of paints are just plastics within a volatile liquid substance, they stick to the resins used in FRP. Now, you can use any resin-based paint on any type of FRP. However, for best results, it’s better to pair paints with FRP using the same resin. Similar resins always bond better together than mixing.
There is one exception: FRP that is subject to heavy water exposure and a lot of minor impacts. In usage within these conditions, epoxy paint is far more durable against fresh or saltwater exposure. Epoxy still performs strong and despite UV rays causing degradation it takes many years to have an effect with a proper coating. In fact, you can be assured that FRP products such as wellhead platforms and grating on rigs will outlast metal counterparts. The pigments used in epoxy-based paints will give the fiberglass a suitable barrier of protection.
What Is The FRP Paint Made From?
Paint no matter the type, is usually made up of a liquid, a binding agent, and the pigment for color. In paints used for FRP, the liquid is a volatile organic compound, polymers for the binder, and the pigment is the coloring.
Volatile Organic Compounds (VOC’s)
VOCs are liquids that evaporate at a very quick rate—the liquid remains fluid long enough for the paint to self-level. However, it also evaporates fast enough to coat durable in a small amount of time. These compounds are not safe to use without protective breathing apparatuses and plenty of ventilation.
Binding agents are chemical compounds that make the particles of pigment stick to each other. Usually, the binder is a resin. In the case of paints for FRP exposed to sunlight and water, those resins are epoxy or polyester.
Pigments make up the smallest part of FRP paints. Even though pigments are made from chemicals, they are usually patented formulas. This means you won’t be able to easily find out the complete makeup of your paint. It is best to discuss with your supplier to determine paint compatibility with your project or part.
Preparation Is Crucial
Preparations for painting FRP are crucial for successful application and durability. You must take proper steps to prep your product. You also need to be aware of environmental conditions when you plan to paint. If it’s too humid (over 60%) and too cold, it will take much longer for the paint to cure or, if cold enough it won’t cure at all. If it’s too hot, the paint will set immediately leaving the layer below basically in a liquid state. You should aim for humidity of less than 60% and a temperature between 66° and 89° degrees Fahrenheit. If conditions are good then you move on to prepping the surface of your product.
Sanding, Cleaning & Paint Application
Surface prep is critical and will comprise upwards of 90% of your labor—if the surface is dirty, oily, or greasy the paint will not adhere at all. Additionally, paint will not adhere to glossy or slick surfaces, so sanding down to the glass strands is crucial.
While painting FRP can be done in two different ways, the best one depends on your equipment and needs. In most cases, for industrial use FRP, it is best to hire an FRP manufacturer to perform paint jobs on products. They will have tHE necessary equipment and know-how to combine the right paint and prep work for your project.
Paint is applied using compressed air with a high-quality spray gun that can cover a large area quickly and evenly. This is the most often used method for commercial FRP products such as grating, panels, and railings.
Roll and Tip Method
The paint is applied with a paint roller and then immediately followed with a fine tip bristle or brush. Often this is used more in home consumer FRP products such as models, outdoor furniture, and others.
Let The Professionals At DEFI Help You!
When all is said and done, FRP does experience wear and tear despite being extremely durable. If your FRP has reached the end of its very long life cycle or needs a new coat of protective paint—contact us. We can help you with new structural FRP or maintenance!