Crystic Iso Brush Gelcoat – 65PA

Isophthalic Brush Gelcoat with Excellent Water Resistance


Crystic Gelcoat 65PA is a pre-accelerated, isophthalic gelcoat. It has been formulated for brush application, but spray versions are available. Crystic Gelcoat 65PA is available in a wide range of colours and the information contained in this technical data sheet also applies to these pigmented versions. A non-accelerated version, Crystic Gelcoat 65, can also be supplied.


Crystic Gelcoat 65PA is designed for use in the marine, building and transport industries. It is also suitable for general moulding requirements.

Features and Benefits

Crystic Gelcoat 65PA has excellent water and weather resistance.


Crystic Gelcoat 65PA is approved by Lloyd’s Register of Shipping for use in the construction of craft under their survey.

When backed with Crystic 356PA, it is capable of obtaining a Class 1 certificate to BS476 Part 7 and of satisfying the requirements of the Building Regulations for a Class O structure. The same laminate can also achieve an M1 rating to the French Epiradiateur NFP 92-501 test.


Crystic Gelcoat 65PA should be allowed to attain workshop temperature (18ºC-20°C) before use. Stir well by hand, or with a low shear mixer to avoid aeration, and then allow to stand to regain thixotropy. Crystic Gelcoat 65PA requires only the addition of catalyst to start the curing reaction. The recommended catalyst is Butanox M50 (or other equivalent catalyst), which should be added at 2% into the gelcoat. (Please consult our Technical Service Department if other catalysts are to be used). The catalyst should be thoroughly incorporated into the gelcoat, with
a low shear mechanical stirrer where possible.

Pot Life

Temperature Pot Life in Minutes
15ºC 24
20ºC 15
25ºC 9

The gelcoat, mould and workshop should all be at, or above, 15°C before curing is carried out.


For normal moulding, the application of Crystic Gelcoat 65PA should be controlled to 0.4-0.5 mm (0.015-0.020 inch) wet film thickness. As a guide, approximately 450-600 g/m2 of gelcoat mixture (depending on pigment) will give the required thickness when evenly applied.


Crystic Gelcoat 65PA is supplied in a wide range of colours. This eliminates the potential for mixing errors with small quantities of pigment paste. The addition of fillers or pigments can adversely affect the water and weather resistance of the cured gelcoat. Crystic Gelcoat 65PA can be used as a topcoat provided that 2% Crystic Solution MW is added to overcome the normal tackiness.

Typical Properties

The following tables give typical properties of Crystic Gelcoat 65PA when tested in accordance with SB, BS, EN or BS EN ISO test methods.

Property Liquid Gelcoat
Appearance mauvish, cloudy
Viscosity @ 25ºC thixotropic
Specific Gravity @ 25ºC 1.11
Volatile Content % 34
Geltime at 25ºC using 2% Butanox M50 (or other equivalent catalyst) minutes 9
Stability @ 20ºC Months 3
Property Fully cured *Gelcoat (unfilled casting)
Barcol Hardness (Model GYZJ 934-1) 42
Water Absorption 24hrs @ 23ºC mg 18
Deflection Temperature under load (1.80MPa)* 0C 75
Elongation at Break %c 3.0
Tensile Strength MPa 75
Tensile Modulus MPa 3500
  • * Curing schedule - 24 hrs @ 20ºC, 3 hrs @ 80ºC
  • * Curing schedule - 24 hrs @ 20ºC, 5 hrs @ 80º C, 3 hrs @ 120º C

Post Curing

Satisfactory laminates for many applications can be made with Crystic Gelcoat 65PA by curing at workshop temperature (20ºC). However, for optimum properties, laminates must be post-cured before being put into service. The moulding should be allowed to cure for 24 hours at 20ºC, and then be oven-cured for 3 hours at 80ºC.


Crystic Gelcoat 65PA should be stored in its original container and out of direct sunlight. It is recommended that the storage temperature should be less than 20ºC where practical, but should not exceed 30ºC. Ideally, containers should be opened only immediately prior to use.


Crystic Gelcoat 65PA is supplied in 25kg and 225kg containers.

Health and Safety

See separate Material Safety Data Sheet.