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RAL 9016 Crystic GT-900 Isophthalic Gelcoat - SPRAY View larger
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RAL 9016 Crystic GT-900 PAX Isophthalic Polyester Topcoat - SPRAY

13,00 €

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Crystic® GT-900 PAX is a high performance isophthalic polyester topcoat. It is filled, pre-accelerated and formulated for spray application.
Crystic® Topcoat GT-900 PAX has been developed to have excellent intrinsic water and weather resistance. It is used for painting the back of polyester parts once demoulded or for repairing a gelcoat surface.

Product Description and Approvals

Crystic® Topcoat GT-900 PAX is a high performance isophthalic topcoat. It is filled, pre-accelerated and formulated for spray application.
Crystic® Topcoat GT-900 PAX has been developed to have excellent intrinsic water and weather resistance. The viscosity profile ensures even coverage with minimal drainage and low film porosity. Crystic® Topcoat GT-900 PAX has been approved by Lloyd’s Register of Shipping.

Crystic® Topcoat GT-900 PAX is recommended for use in the marine, building and transport industries. It is also suitable for general moulding requirements.

GelTint offers the latest in pigment and gelcoat technology producing a high quality product for ease of use, finish and longevity. There is a vast range of colours available. Custom colour matching is also available if required once you contact a Castro Composites representative.

The biggest benefit of GelTint is the speed

Features and Benefits


  • Isophthalic base resin
  • High elongation
  • Easy to apply
  • Low styrene emission


  • Excellent water / blistering resistance
  • Good impact resistance
  • Excellent surface finish
  • Less exposure to the environment and operators

Spray set up

  • Application temperature: 15 - 25°C
  • Catalyst: 2% MEKP 50% or equivalent catalyst.
  • Nozzle airless gun: 423 - 535
  • Pressure: 3 to 4.5 bars
  • Distance to mould: 50 cm minimum
  • Wet film thickness: 600 - 800 microns

Spray Application


- Ensure the topcoat has attained workshop temperature of 15°C - 25°C before use.
- Add 2% MEKP at 50% or equivalent catalyst.
- Gently stir the topcoat by hand or low shear stirrer.
- Spray at the minimum practical pressure whilst maintaining an acceptable spray pattern and full fan width.
- Apply a mist coat and then build up thickness in long, even passes of 100 - 150 microns until the recommended wet film thickness of 600 – 800 microns is reached.


- Stir the topcoat with high shear mixers as this will temporarily break down the thixotropy leading to drainage.
- Exceed a wet film thickness of 800 microns as thick films encourage air retention.
- Apply excessive thickness in corner areas as this can cause exotherm issues and undesired shrinkage.
- Catalyse more topcoat than can be applied before it starts to gel as this will lead to wastage and possible exothermic reaction.
- Allow vapour to be retained in deep mould sections as this can cause slow curing.

Additives and Variants

Crystic® Topcoat GT-900 PAX should only be used with specified GelTint pigments. The information contained in this technical data sheet applies to all pigmented versions.

Incorporation of additional material may affect the working, weathering or cured properties of the gelcoat. Please check with Castro Composites’s Technical Service department before using the gelcoat outside of specified parameters.


Satisfactory laminates for many applications can be protected at the back with Crystic® Topcoat GT-900 PAX by curing at workshop temperature (15°C - 25°C). 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 workshop temperature and then oven-cured for 16 hours at 40°C.

Recommended Testing

It is recommended that customers test all pigmented gelcoats before use under their own conditions of application to ensure the required surface finish is achieved. We recommend that Customers new to GelTint or customers using new GelTint colours test the product before use in full scale production. Due to the nature and fast service of the GelTint process, retain samples of the final product are not taken.

Packaging and Storage

Crystic® Topcoat GT-900 PAX should be stored in its original container, under cover, and out of direct sunlight. These must be kept closed and airtight. It is recommended that the storage temperature should be less than 25ºC and the product should not be frozen. Storing the product outside of these conditions may affect the properties of the product and reduce its shelf life. Ideally, containers should be opened only immediately prior to use. Material should be used within 5 months of production.

Health and Safety

Read and understand separate Material Safety Data Sheet before using this product. Unsaturated polyester products release heat when they cure in bulk.

Type of supply

Crystic Topcoat GT-900 PAX x 1 kg* container supplied with 20 g of catalyst

Crystic Topcoat GT-900 PAX x 5 kg* container supplied with 100 g of catalyst

Crystic Topcoat GT-900 PAX x 18-20 kg* container supplied with 0.5 kg of catalyst

* Weights shown are estimated since depending on the RAL color selected, weight content may vary slightly. To see the exact quantities of each RAL color, please click on the following link: Total package weight per RAL

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