General Purpose Ortophtalic Gelcoats

General Purpose Ortophtalic Gelcoats

Gelcoat is the outermost structural layer on a composite part, designed to protect the underlying fiberglass layers. Gel coat makes fiberglass reinforced products attractive and practical. Technically, it is a surface coating of pigmented polyester resin which gels against the mold surface and cures with the structural laminate. It faithfully reproduces the mold surface, imparts color, and protects the reinforcing fibers from external elements. In many cases, the surface treated with gel coat is the only part of the structure that can be seen. To the user, it is simply a reinforced plastic. Resins, fillers, pigments and promoters are carefully selected and formulated to develop the quality and surface appearance needed to make the product durable and saleable. Customer acceptance of the product can depend entirely upon the care and handling of gel coat.


These general purpose economic gelcoats are suitable for industrial use. General Purpose Gelcoats  are not suitable for chemicals, heat and water resistance need products.


Product Features

  • Spray & Brush type available
  • Transparent & Colored type available
  • 5 & 25 kgs pail.
Category: .

Application Instructions

Gelcoat Storage

  • Keep gelcoat stored in original containers at appropriate temperature (~20°C is ideal).
  • Ensure good stock rotation. (The older a gelcoat is, the more the low shear viscosity will have drifted, and the more prone the gelcoat will be to sagging.)
  • Mix the gelcoat in the keg/drum before decanting.

Workshop & Mould Preparation

  • Where possible, keep the workshop and mould temperature to ambient (around 20°Cis ideal).
  • Ensure that the mould is clean, dry and an appropriate release agent has been correctly applied.

Gelcoat Weighing & Addition of Catalyst

  • Ensure that the weighing area is clean and free from contaminants.
  • Accurate weighing of the gelcoat is required for catalyst dosing to be accurate.
  • Keep different coloured gelcoats well apart.
  • Add the correct (and consistent) amount of the correct catalyst to each portion of gelcoat.
  • Mix the catalyst into the gelcoat thoroughly with clean mixing apparatus before application begins.

Gelcoat Application

  • Avoid pouring the gelcoat onto the mould surface. This will leave a colour fault on the demoulded surface.
  • Always use a clean brush, roller or recently cleaned spray equipment.
  • Avoid excessive thickness in one application. This will lead to slumping and/ortearing.
  • Minimise drips and runs wherever possible (through applying at correct thickness).
  • Avoid very thin application (<200μm) as this will lead to poor cure.
  • The film must not be disturbed once cure has begun (time will be dependent on catalyst level and temperature of application).

Brush Application

  • Apply the gelcoat by brush in at least two directions. This helps to reduce the effect of brush-marking.
  • Good brushing improves the air release in a gelcoat layer (the air release additive used in brush gelcoats relies on shear to work).
  • Laying off with a brush will help to remove air.

Spray Application

  • Spray application will help to eliminate variations in thickness and give a moreconsistent gelcoat film.
  • It is important that the spray equipment is set up to give a good fan to achieve the optimum spray pattern.
  • Spray in even passes in a number of directions until the required thickness.

Application of the Backing System

  • The back surface of the gelcoat must be kept clean and free from dust and moistureuntil the backing system is applied.
  • The backing system should only be applied after the gelcoat film is sufficiently cured.
  • Good consolidation of the backing system is vital to avoid blistering issues.