I'm preparing to tile a bathroom wall with white 100x200mm tiles. For aesthetic reasons, I'd like to use contrasting grout in a bright vivid colour. All the pre-coloured grouts I can find for sale are shades of grey and beige. What would be the best way to add colour to white tile grout?
I'm leaning towards stirring paint into pre-mixed grout, or else mixing my own grout replacing some of the water with paint. But I'm not sure what type of paint to use, how intense a colour I could reasonably expect, and whether doing this might affect the grout's ability to do its job.