Choosing your resin or mastic
Resin is used to laminate, repair, or reinforce a hull, centerboard, or rudder. The two main families, epoxy and polyester, do not have the same properties or the same compatibility. Here are 5 points to check.
1. The original material
Polyester resin is used on polyester parts, which make up the majority of production hulls. Epoxy resin adheres to polyester, epoxy, wood, and metal. Conversely, a polyester resin will not adhere properly to an epoxy part. If in doubt about the original material, epoxy is compatible with more substrates. See the Soromap polyester resin and the epoxy resin + catalyst.
Soromap polyester resin
2. The type of repair
For a structural repair (through-crack, mounting reinforcement, centerboard or rudder), epoxy offers higher adhesion and mechanical strength. For standard lamination on a polyester hull, polyester resin with glass mat is suitable and remains more economical. For a small, localized repair, a ready-to-use kit simplifies measuring, such as the Talamex epoxy repair kit.
Talamex epoxy repair kit
3. Mixing and application
Polyester resin is catalyzed with a small percentage of hardener: the Soromap polyester resin is dosed at 2 to 3%, which allows you to adjust the setting time. Epoxy resin requires a precise mixing ratio between resin and hardener that must be strictly followed: incorrect dosing prevents complete polymerization. In both cases, ambient temperature influences working and setting time; work on a clean, dry, and sanded surface, using gloves and ventilation.
4. Fillers and thickening agents
To fill or bond, the resin can be thickened. Silica gel is added to epoxy or polyester resin (2 to 3% by weight) to make it thixotropic and prevent it from running on a vertical wall. For filling, a pre-filled product like Speed Filler fast epoxy filler avoids the need to prepare the mixture (see also our filler guide).
Silica gel 1 kg
5. The finish
Epoxy resin degrades under UV rays: it must be covered with paint or varnish. On a polyester hull, finishing is generally done with a gelcoat or topcoat, for example the Talamex clear topcoat, which can be tinted with pigment for topcoat. After wet sanding, polishing paste restores the gelcoat's shine.
Talamex clear topcoat
Find all products in our resins and fillers collection.