What is chalking?
Chalk is a white powdery substance found on coatings and gel coat. The resin binder eventually breaks down due to ultraviolet (UV) exposure and exposes the pigment. The powdery substance is the breakdown product of the pigment.
What is a gel coat?
A gel coat is a specialized resin that imparts colour to fabricated products. It contains UV additives, pigments, activators, and rheological chemicals to control the resin flow on a vertical surface. They have a much higher viscosity than laminating resins and is the first resin applied to the mould.
The fibreglass structure should be properly prepared to receive the chosen coating. Lightly sand the pool to remove any surface contaminants and clean it thoroughly. There is no need to remove the old gel coat. Be sure to use a compatible primer with the coating selection. For pools with a lot of blisters, sand the blisters and dehydrate the fibreglass.
Coating choices
- Two-part epoxies with a short service life.
- 100 per cent solids, zero volatile organic compounds (VOCs) novolac epoxies.
- Polymer composite resins incorporating BPA EVER for a long service life. This will eliminate blistering and repeated resurfacing.
- Modified isophthalic neopentyl glycol (ISO/NPG) gel coats for long service life.
The purpose of these coatings is to improve the esthetic appeal of old fibreglass pools, and to protect the underlying laminate or pool structure. Once the gel coat wears away, the pools lose the uniformity of appearance and look dull and uninviting.
The coatings mentioned are the main options available, because in the coatings industry, very few coatings perform well in pools, hence the limitation in options. It is recommended to use only performance coatings for pool resurfacing, because if not, it will certainly deteriorate fast, and lead to rework.
