System Additives

Pigmenting Gelcoats & Resins

Pigment AdditionThe entire purpose of a Polyester or Polyurethane Pigment is to simply colour a resin or in the case of Polyester a gelcoat. These can be ordered via our standard colour chart or indeed by RAL & British Standard Colour numbers. We stock a small number of popular colours including Black, White and Dark Grey at all times, other colours come into and go out of stock all the time.

To add pigment, use a ratio of 7-8% for dark colours and up to but NEVER exceeding 10% for lighter colours. In particular Yellows tend to require maximum addition ratios. Excessive pigment use will result in poor curing and possible softening or weakening of the laminate or gelcoat. You can also provoke a "primer grey" appearance in our Fast Cast system with a small 0.5% addition of black pu pigment.

If you are to be using a pigment in gelcoat or resin for use with a pond, please ask us if the pigment is Lead Free. Most of our pigments are now lead free due to Health & Safety at work regulations, however sometimes it's impossible to be lead free. If in doubt ask!


Wax Additive Use

Wax Additive is added to gelcoat at a ratio of 2% maximum to alter the product completely. In fact gelcoat containing wax soloution isnt call gelcoat, it's renamed to Flowcoat or Flo-coat.

When using a gelcoat out of a tool, failure to add wax solution will result in a tacky finish to the gelcoat. When you add wax to gelcoat at 2% and apply as a top coat (repairs to laminates, flat roofing or pond construction) during the cure the wax comes to the upper surface of the gel, forming an airtight barrier.

This will stop the cured gelcoat being tacky on hardening. NEVER use wax in a gelcoat to be used in a tool, the wax will act as a release agent betwen the gelcoat and laminate and cause it to fall away. Just remember to fully disperse the wax at 2% by weight prior to catalysation.


Filler Powder Addition

Now suggested ratios for use when it comes to filler powders is a hard topic. Everyone uses a different ratio. And its application specific too! The best actions to take when first using a filler powder is to start at a LOW percentage, say 10% and then move up the scale. Adding at more than 100% rarely gives improvement, or at least very little, to physical properties of a resin. In fact if you exceed 140% by weight you will most likely weaken it.


Chopped Strand Filler Paste

Frequently you may require a filler paste that's glass reinforced for extra strength. or indeed you might want to fill a gap with a composite where it's not practical to use lamination techniques. By adding loose chopped strands to a resin you will rapidly increase its viscosity, but again it's very much a case of add enough but not too much! The best way to guage from our own experience is simply add until you get a thixotropic paste, then catalyse and use.

The compressive strength of such a filler paste is huge. We have used this to successfully level floors underneath heavy racking where several tonnes of force are being applied. Our "home-made" feet for our racking have yet to break after 5 years heavy use. You should ensure that the system will be fit for the job however!


Home Made Easy Sand Filler

Why buy expensive pre-made fillers to use in repairs to car bodies, boats etc. You can make your own equivalent to Isopon P38 or P40 by using french chalk and choppies. To make non glass reinforced paste simply empty a kilo of resin into a paint can that you can re-seal and add french chalk to the resin until no more can be dispersed. At this stage remove your required quantity and seal the container. If you don't seal it the styrene will leech away leaving a poor resin base and therefore a weak filler that won't cure right.

To make a glass reinforced filler like Isopon P40 add a handful of 4.5mm choppies to the kilo of resin first, then add french chalk until no more can be dispersed just like above. Again remove what you need and seal the tin!

By then catalysing with MEKP @ 4% you have a very easy to sand yet incredibly low shrinkage filler, ideal for reapirs to rigid tools, laminates, car bodies and more. Whenever you sand remember to use a dust and particulate respirator, polyester dust and glass fibres are very bad for your health.