WEST SYSTEM® 501 White Colour Pigment is an epoxy-based paste used to tint the epoxy mixture and provide an even colour base or highlight surface flaws and imperfections, prior to the final finish system.
As a guide, a 125ml container of pigment will be suitable for 2.9 litres of mixed epoxy.
Note that pigmented epoxy will degrade under sunlight and is not intended as an exterior finish. An enamel or polyurethane paint system will need to be applied to provide UV protection.
As expected, the pigment mixes very easily with the West epoxy resin. At the recommended quantities, the pigmented epoxy has very "thin" hiding power, which is of no concern if you're just wanting a visible guide coat. However, if you need to achieve an opaque full bodied colour surface, at least three coats are required, with rather generous addition of the pigment. On vertical surfaces, resist the temptation to lay it on thickly or it will sag badly.