Shopping Cart
- Feroca
- Fibreglass
- 0 likes
- 316 views
- 0 comments
Polyester resin is one of the most versatile materials in the workshop: affordable, fast-curing and compatible with fibreglass to build rigid, strong parts. Whether you need to repair a swimming pool, manufacture a structural casing or create inclusion effects with objects embedded inside, polyester is your starting point.
What is polyester resin?
Polyester resin is a thermosetting polymer that comes as a viscous, single-component liquid. To cure it requires the addition of a catalyst — usually an organic peroxide such as Catalyst F11 — which triggers an irreversible exothermic reaction: the resin transitions from a liquid state to a rigid solid without the need for external heat.
Unlike epoxy resins, polyester works with very low catalyst ratios (between 1 and 2% by weight), making it easy to adjust working time according to ambient temperature. Its main drawback is styrene, a reactive solvent responsible for the characteristic odour and some of the emissions during curing. Modern low-styrene formulations — such as DCPD — significantly reduce this problem.
From a structural standpoint, cured polyester is rigid, with good resistance to compression and water, although somewhat more brittle than epoxy under impact. This is why it is typically used in combination with fibreglass reinforcements that compensate for this limitation and multiply its mechanical strength.
Types of polyester resin
At Feroca you will find three Ferpol formulations, each optimised for a specific use:
| Product | Application | Mix ratio (A:B) | Working time | Cure time | Colour |
|---|---|---|---|---|---|
| Ferpol 100 BSX15 DCPD | Fibreglass laminates, swimming pool repair, structural casings | 100 : 1.5 | 20 min | 1 hour | Reddish (cured: violet) |
| Ferpol 1973 | Object inclusions, orgonites, glass effects and decorative water | 100 : 2 | 35 min | 100 min | Colourless transparent |
| Ferpol 3501 CV2,5 | Mould casting, low reactivity, extends silicone mould life | Variable | 10 min | 20-25 min | Bluish transparent |
If you are looking for a kit to get started without buying each component separately, the Polyester Resin Repair Kit includes Ferpol 100 BSX15, fibreglass mat, deaeration roller, brush and acetone: everything you need for your first part or repair.
Main uses and applications
Polyester resin covers a wide range of applications thanks to the diversity of its formulations:
- Swimming pool repair: Ferpol 100 BSX15 is the standard choice for sealing cracks and reinforcing deteriorated areas in polyester pools. It is applied with fibreglass mat in two or three layers to restore structural waterproofing.
- Building casings and rigid moulds: when you need a containment casing for a flexible silicone mould, polyester with fibreglass is the most affordable and fastest material for achieving structural rigidity.
- Fibreglass laminates: in combination with Fibreglass Mat 300 g/m², lightweight and strong parts are produced: body panels, covers, decorative panels, structural prototypes.
- Inclusions and orgonites: Ferpol 1973, transparent and colourless, allows objects (crystals, metals, plants, photographs) to be embedded inside resin blocks. It is the standard choice for orgonites and decorative inclusion pieces.
- Water and fictional beverage effects: its watery appearance when lightly pigmented makes it useful for recreating liquid surfaces in scale models, dioramas and audiovisual production props.
- Silicone mould casting: Ferpol 3501, with low viscosity and low reactivity, generates less heat during curing and reduces thermal stress on the mould, extending its service life in long production runs.
- Surface protection: applied in thin coats over porous structures (wood, plaster) it acts as a sealer and waterproofing agent.
How to use polyester resin step by step
The process varies depending on whether you are laminating or casting, but the fundamental steps are common to both:
- Prepare your workspace. Work in a well-ventilated area. Wear nitrile gloves, a respirator with an organic vapour filter and safety goggles.
- Prepare the mould or surface. If using a mould, apply release agent and allow to dry. If repairing an existing surface, sand the area and clean with acetone.
- Cut the reinforcement if applicable. For laminates, cut the mat into manageable pieces before adding the catalyst to the resin.
- Weigh and catalyse the resin. Always use a scale. For Ferpol 100 BSX15: 100 parts resin to 1.5 parts Catalyst F11. Mix for 2–3 minutes until completely homogeneous.
- Apply the first coat. Using a brush, wet out the mould or surface. For laminates, place the mat onto the wet layer and saturate with more resin using the deaeration roller, eliminating bubbles.
- Add successive layers. Wait for the previous layer to gel before adding the next one. For a structural casing, 2–3 layers of 300 g/m² mat is standard.
- Leave to cure undisturbed. Polyester generates heat as it cures. Do not move the part until it has fully solidified.
- Clean tools immediately. Use acetone before the resin hardens. Once cured it is impossible to remove.
Caution: polyester catalyst is an organic peroxide. Never mix it directly with the accelerator without the resin in between: the reaction can be violent. Store both components separately and at a cool temperature.
Advantages and disadvantages compared to epoxy resin
Choosing between polyester and epoxy depends on the project. This table summarises the key differences:
| Property | Polyester resin | Epoxy resin |
|---|---|---|
| Price | More affordable | More expensive |
| Odour during curing | Strong (styrene); lower in DCPD formulations | Moderate or low |
| Transparency | Good in specific formulations; may yellow over time | Excellent; greater UV stability |
| Mechanical strength | High in fibre laminates; more brittle alone under impact | Greater toughness and impact resistance |
| Cure shrinkage | Higher (3–8%) | Lower (1–3%) |
| Cure speed | Fast (20 min – 1 hour depending on type) | Variable (2–24 hours depending on system) |
| Best for | Fibre laminates, pools, mould casings, budget inclusions | Jewellery, river tables, high-quality reinforcements, deep pours |
Frequently asked questions
What type of fibreglass is used with polyester resin?
For laminates with Ferpol 100 BSX15, the most common reinforcement is Fibreglass Mat 300 g/m². If you need greater strength in specific directions, combine it with woven fibreglass fabric. For the final layer, a 34 g/m² surface veil eliminates roughness and improves the finish. Browse the full range of fibres and fabrics.
What catalyst ratio does laminating polyester resin require?
For Ferpol 100 BSX15, the standard ratio is 1.5% by weight (100 parts resin to 1.5 parts Catalyst F11). At low temperatures (below 18 °C) you can increase this to 2%. Never exceed 3%. Always weigh the components on a scale.
What is transparent polyester resin used for?
Ferpol 1973 is designed for inclusions: embedding objects (flowers, minerals, photographs, metals) inside a transparent resin block. It is also used for orgonites, water effects in scale models and dioramas. Its 35-minute working time allows objects to be positioned before gelation.
Can polyester resin be used with silicone moulds?
Yes, polyester resin is compatible with silicone moulds. The only precaution: liquid polyester can inhibit platinum silicones if they come into contact before it cures. Once the resin is fully cured, there is no risk.
What are the differences between polyester resin and epoxy?
Polyester is more affordable and cures faster: ideal for fibreglass laminates and structural repairs. Epoxy offers greater optical clarity, lower shrinkage and better adhesion to metals and wood. For jewellery, river tables or resin art, epoxy is superior. For strong structures where cost matters, polyester wins.
Also see our post on how to repair a crack in a swimming pool with fibreglass and polyester or explore the full range of reinforcement fibres and fabrics.
Comments (0)