Why are some resins called waxed and un-waxed?
These terms usually talk about polyester resins, the first one waxed is a orthophthalic resin used in general fibreglass work where it is usually left a “natural” finish.This resin has a wax added to it to protect the resin and underlying glass fibres from moisture penetration. The wax coming to the surface as the resin starts to cure (dry). for most diy repair projects rhe reain supplied in kits will be waxed resin. The other resin which is called isophthalic resin is sold un-waxed, this resin is also a little bit more expensive to buy, is a higher quality resin being stronger in nature, has better chemical resistance and is usually the preferred resin used in fibreglass boat building and repair work as it can be left for a day or two without sanding prior to further laminate build up. Wax is best added to this resin on the last coat if it is being used under a boat floor/hull situation or left without surface finishing (e.g. painting) to protect from moisture entry.
