Amateur: Additive of the Month – Colour Pigments
WEST SYSTEM® Colour Pigments are available in four basic colours.
What are Colour Pigments?
WEST SYSTEM 501-505 Colour Pigments are made from stable coloured materials incorporated in an epoxy resin base. Currently there are white (501), black (502), grey (503) and blue (505) pigments to choose from.
Used for? Pigments are added to a clear epoxy to give it a rich, deep colour. The intention is that they will act as a uniform undercoat to a final layer of either a UV-stable varnish or a paint system.
Mixing ratio: Add between 3-5% by weight to the epoxy mix.
Don’t add too much
“The pigments are epoxy based, so don’t exceed the maximum percentage. Up to 5%, there will be no significant deviation from the established ratio of the epoxy resin and hardener. Therefore addition of pigment to the mixed epoxy will not change the cure time or physical properties of the cured mix.”
Use in the final coat
“Ideally the colour pigment should only be used in the final coat of epoxy. The epoxy will be slightly thicker when carrying pigment, so won’t penetrate and seal the substrate as effectively if used throughout. If you want good absorption into the timber, use un-thickened epoxy first and exclude the use of any additives. You can build up pigmented layers on top.”
Mix with a dab motion to start
“I give this advice with all additives. Make sure you wear a mask, gloves and safety glasses and start the mix with a dabbing motion. You can stir more thoroughly once most of the pigment has been dabbed into the resin.”
“For small jobs one batch will probably be enough. If you’re using the pigments to make up a pigmented gelcoat for example, you will need to be more exact with the mixing ratio. Use precise measurements – digital scales are the most dependable – to ensure that the weights of material (resin, hardener and pigment) stay absolutely consistent throughout the job. If you’re going to overpaint this is not really an issue but if the pigment will serve a decorative purpose, perhaps displayed under UV gloss varnish, you have to ensure it remains exactly the same shade.”
Protect from UV
“No formulation of epoxy is totally UV stable. Always make sure that your epoxy coatings are protected if they are going to be exposed to direct or indirect sunlight. This includes the pigments. Some products like 207 Special Coatings Hardener increase UV protection but the ultimate protection comes from paints and varnishes that have been formulated to resist the effects of UV degradation.”