Fibreglass projects rely on resins as the backbone of their strength, durability and stunning finish. Whether you’re repairing a boat hull, installing a GRP roof, or building a moulded panel, resin is the material that binds fibres together and creates a tough, protective, long-lasting surface. But while the structural role of resin is essential, there’s also another layer of potential... and that's colour. By adding pigments or dyes, you can transform the finish of a fibreglass project to meet your practical needs and aesthetic goals.
However, choosing to add colour to your resin isn’t simply about looks; it’s about taking control of the final look, performance, and personality of your project. In roofing, pigments allow topcoats to blend seamlessly with the rest of your property. In boatbuilding, dyes can give a professional, polished finish that also provides UV resistance as well. In DIY, creative or decorative work, pigments can produce solid, bold shades, while translucent dyes can create striking visual depth. The right colouring agents give fibreglass projects not only durability but also the high-end style and finish that customers desire.
But adding pigments and dyes to resin must always be done correctly. Using the wrong type, measuring poorly, or mixing incorrectly can all lead to problems - from uneven colour and streaking to weakened laminates or curing issues. A project that looks perfect at first can quickly become a costly re-do if these details are overlooked. That’s why understanding the process is so valuable.
In this resin colouring guide, Fibreglass Supplies Ltd will show you how to successfully add pigments and dyes to resins used in fibreglass work. From roofing and boat repairs to automotive mouldings, ponds, countertops, and even creative projects like river tables and jewellery, we’ll cover the benefits, potential pitfalls, and the proven steps that help you get it right the first time.
Understanding Pigments & Dyes In Fibreglass Resins
Before adding colour to resin, it’s vital to understand the difference between pigments and dyes. Although they both change the appearance of resin, their chemistry and behaviour are completely different. Using them correctly ensures you get the finish you want without compromising curing or strength.
Pigments: Insoluble colour particles suspended in the resin to create a solid, opaque finish. Because they block light transmission, pigments are used when strong, uniform colour coverage is required. They are essential in GRP roofing, automotive bodywork, and moulded panels where consistency and durability matter.
Dyes: Soluble colouring agents that fully dissolve into the resin, producing transparent or translucent effects. Because they allow light to pass through, dyes are used in decorative castings, resin jewellery, pond linings, or river tables where visual depth and clarity are desired.
Compatibility: Always ensure pigments or dyes are formulated for the resin system you are working with - polyester, vinylester or epoxy - otherwise an incompatible additive can cause curing failures, streaking or weakened laminates.
Epoxy vs Polyester Pigments: What’s The Difference?
Each resin system demands its own colourants, and using the wrong type can cause curing failures or poor finishes. Epoxy pigments are formulated for clarity and thickness, while polyester pigments are styrene-based for strength and weather resistance.
Epoxy Pigments: Supplied mainly as liquid pastes for opaque tones or as transparent tints for coloured glass-like effects. Because epoxy has a higher viscosity, these pigments disperse evenly without clouding. Used in river tables, resin jewellery, flooring and artwork, make sure you keep the loading level under 10% of resin weight to avoid soft spots or curing delays.
Polyester & Vinylester Pigments: Styrene-based pastes designed to lock into polyester chemistry. They are compatible with gelcoats and topcoats, so the finish is both UV and weather-resistant. Commonly used for GRP roofs, boat hull repairs, car panels, and moulded components. Apply at 5 - 10% loading for vibrant, durable colour.
Golden Rule: Never cross-use pigments. Epoxy pigments will not cure in polyester, and polyester pigments will weaken epoxy. Stick to the system designed for your resin for a professional, lasting finish.
Why Add Colour To Fibreglass Projects?
Colour has an immediate visual appeal that can transform a fibreglass project from purely functional into something that looks professional and refined. A plain resin surface may be strong, but adding pigment or dye introduces character, style and polish. The good news is that colouring resin is relatively straightforward - most pigments and dyes are designed to blend easily into resins with just a few extra steps. That said, care is needed: too much pigment can disrupt curing, and choosing the wrong additive for your resin type can lead to disappointment. Done properly, however, colour becomes a powerful tool that enhances not just appearance, but also performance and value.
Improve Aesthetics: A coloured resin layer ensures repairs blend invisibly with surrounding surfaces, or that new work looks clean and professional rather than patchy.
Enhance Protection: Pigments are not just cosmetic. Many coloured topcoats offer extra UV resistance, helping to prevent yellowing, chalking and surface degradation over time - a crucial benefit for outdoor and marine projects.
Support Branding: In commercial or industrial work, colour consistency matters. Whether it’s matching a company’s signature blue or producing a uniform fleet of panels, pigments allow fibreglass to meet a number of corporate-level requirements.
Enable Creativity: Transparent dyes as well as metallic and special effect pigments open up a world of artistic possibilities. River tables, jewellery, ponds, or resin artwork all benefit from the visual depth and unique finishes that only coloured resins can provide.
Choosing The Right Colouring Additives
Not all colouring options are created equal, and choosing the wrong one can compromise both the look and performance of your resin project. Each additive has its own chemistry and physical properties, which means it will interact with resin differently. Some are designed to bond seamlessly with polyester and vinylester systems, while others maintain clarity in epoxy resins. Beyond compatibility, the choice affects the final finish - whether you’re aiming for a smooth, uniform colour, a clear tinted effect, or a metallic shimmer. Selecting the right additive ensures the resin cures properly, avoids clumping or separation, and produces a finish that lasts as long as the fibreglass itself.
Polyester & Vinylester Pigments: Styrene-based pigment pastes that chemically align with polyester and vinylester resins. They’re the industry standard for GRP roofing, ponds, and boat repairs because they deliver strong, even coverage and weather resistance.
Epoxy-Compatible Pigments & Dyes: Formulated for epoxy’s thicker viscosity, these liquid colourants maintain clarity while dispersing evenly. They’re essential for projects like river tables and jewellery where depth and transparency are part of the appeal.
Powdered Pigments: Often used for decorative effects or experimental projects. While they can create unique looks, they require careful blending to avoid speckling or uneven results. These are best for smaller, controlled applications where minor imperfections are acceptable.
Metallic & Pearlescent Additives: Provide shimmer, sparkle and visual depth, making them popular in artistic or high-end finishes. These are best used in surface layers or topcoats rather than throughout the laminate, where their reflective qualities are most effective.
Other Considerations: Think about the long-term demands of the project: Will it be exposed to sunlight, saltwater or constant wear? UV stability, colour fade resistance and chemical durability are just as important as appearance. Always follow supplier guidance to ensure your chosen additive won’t weaken or compromise the resin system.
Step-by-Step: How To Add Pigments & Dyes To Resin
Adding colour is straightforward, but resins are unforgiving: small errors in measurement, order, or mixing energy can snowball into streaking, soft cures or uneven shades. This step-by-step ensures you know exactly how to mix pigments into resin for a professional, repeatable finish. It helps control dispersion (so colour is even), preserve the correct cure chemistry (so strength and hardness aren’t compromised), and manage bubbles, gel time, and batch-to-batch consistency (so large areas match perfectly).
Measure accurately: Always weigh pigment against resin using a precise scale. Typical loading is 0.5–5% for epoxy and 3–10% for polyester/vinylester. Too little produces weak colour; too much risks curing failure.
Pre-disperse pigment: Blend pigment into a smaller portion of the resin first to create a concentrate, then mix it back into the bulk resin. This prevents clumps and ensures an even tone.
Mix thoroughly: Stir slowly but consistently, scraping the sides and bottom. Allow the resin to sit briefly so air bubbles can rise before moving on.
Add catalyst/hardener next: Always introduce curing agents after the pigment is fully dispersed. Follow datasheet ratios exactly, as adjusting them to “balance” pigment can ruin curing.
Test a sample batch: Apply a small batch to a test piece and check colour strength, curing and finish. This will help you avoid project-wide disappointment.
Maintain consistency across batches: For larger projects, mix master batches or carefully weigh every mix to avoid shade differences. Stable room temperature (18–22 °C) helps keep colour and cure consistent.
Important: Consider pot life (pigments can slightly shorten or extend working time), surface preparation (bubble release and film thickness affect appearance), and storage (keep pigments sealed and stirred if separated). Making a note of your pigment ratios and results makes colour-matching easy for future projects.
Common Mistakes & How To Avoid Them
Colouring resin looks simple, but mistakes at this stage can derail an entire project. Adding pigment at the wrong time, using too much colourant, or choosing the wrong type may not show up immediately - but the consequences are significant. You could end up with uneven streaks that ruin the finish, soft or tacky resin that never fully cures, or laminates that lack the strength to perform under stress. This doesn’t just mean a disappointing result, but wasted materials, costly rework, and delays that push back project deadlines. Knowing the most common pitfalls - and why they matter - helps you avoid frustration and keeps your project on track.
Adding pigment after catalyst: Pigment won’t disperse properly once the catalyst or hardener is in, leaving behind swirls and patches. It also risks interfering with curing. Always colour the base resin first.
Overloading pigment: More is not better here. Excess pigment blocks the curing reaction, leaving resin tacky, soft or brittle. Stick to recommended loading levels for a professional finish.
Using the wrong pigment type: Polyester pigments in epoxy (or vice versa) prevent proper curing. The result is wasted resin and failed laminates. Always check compatibility before mixing.
Uneven mixing: Poor stirring leaves streaks, patches or even weak laminate bonding. This compromises both appearance and structural performance. Take your time and scrape the sides and bottom of the cup thoroughly.
Skipping test batches: Colours often shift once cured. Without a test run, you risk inconsistent shades across larger projects, forcing you to redo work or live with mismatched results.
Safety Considerations When Using Pigmented Resin
Working with resin is as much about safety as it is about technique. Pigments, resins, and catalysts all contain chemicals that can irritate skin, damage eyes, and release fumes that are harmful if inhaled. These risks multiply when you’re working indoors or handling larger volumes. Prioritising safety protects not only your health, but also the quality of your work. A well-ventilated, properly equipped workspace reduces the chance of accidents and contamination that can ruin your latest batch of mixed resin.
At Fibreglass Supplies, we stock a wide range of Cleaning Materials & PPE designed specifically for fibreglass work, so you can stay safe and confident while producing professional results.
Gloves: Nitrile or chemical-resistant gloves prevent skin irritation and chemical burns from resin, solvents, and MEKP catalyst.
Protective eyewear: Safety goggles or wraparound glasses shield eyes from splashes that could cause serious injury.
Respirators: Essential when working with volatile solvents, catalysts, or in enclosed areas. They prevent the inhalation of fumes that cause headaches or long-term health issues.
Ventilation solutions: Extraction fans or open, well-aired workspaces reduce fume build-up and create a safer environment.
Protective clothing: Disposable overalls or long-sleeved garments prevent resin from contacting skin and stop pigment stains from ruining clothes.
Storage equipment: Sealed containers and cool, dark storage areas keep resins and pigments stable and safe between uses.
Applications Across Fibreglass Projects
Coloured resins open the door to an incredible range of possibilities, from small DIY repairs to high-end professional work. For the hobbyist, they make projects more rewarding and visually striking. For contractors and professionals, they offer a way to deliver work that’s not only durable but also tailored to customer expectations. The ability to customise colour ensures consistency, professionalism, and often, added longevity when UV-blocking pigments are used. Whether you’re matching an existing surface or creating something entirely new, coloured resins give you the freedom to balance strength with style.
DIY resin tinting projects: Small repairs around the home, garden ponds, or decorative panels become more attractive and cohesive with coloured resins.
Roofing: Pigmented topcoats help new roofs or patch repairs blend smartly and seamlessly with existing structures while adding UV protection for longevity.
Marine repairs: Boat hulls benefit from pigments that restore a consistent finish and protect against saltwater and sun exposure.
Automotive applications: GRP panels and moulded parts gain strong, even colour that matches existing paintwork or creates custom looks.
Creative & artistic work: From river tables to jewellery and resin art, dyes and metallics add depth, sparkle, and individuality, transforming fibreglass into a creative medium.
Commercial & industrial projects: Matching corporate colours or creating branded finishes ensures a professional, on-spec result that meets client expectations.
