Coloring MCR tiles

by Kurt Rhyner   

The theme comes up at all workshops and with most clients. Many people have made their experience and I will try to resume them.
The easiest way is painting the tiles after producing them. It is usually done with water based paint as is commonly used for painting cement surfaces. If the paint is good, and if two layers are being applied, the results are good, the tiles keep their vibrant color for several years and then slowly fade, at an even pace. As the paint usually contains some fungicide, they are not easily invaded by fungus. Painting is not cheap if well done, but usually less expensive than produce tiles with an integrated color. In the Dominican Republic people have taken to paint the tiles with glossy oil paint. It looks good when new, but we are somewhat careful about recommending it.

 
Colored TMC in Ecuador

The classier, but usually also the more expensive way is to produce colored tiles. The choice of which pigment to use is not easy, we have found out that more expensive ones usually do have more power, and at the end they might be cheaper. Generally it is recommended to use artificial colorants. If your sand is white or almost white, the pigments will be able to develop their strength, but if your sand is dark, it might be very costly to get a strongly colored tile.
How much pigments do you need? If the sand is white and the pigment strong, with 2 or 3% of the weight of the cement (1 Kg of pigment per bag of cement) you should get a nice tone, mainly if red is your choice. However, if your sand is dark or the pigment less strong, you might have to put up to five times more into the mix, and then it becomes really expensive. Some colors are really difficult to achieve, green for instance and light yellow.

I think there is a general rule:
If the client wants a mellow tone (like burnt clay tiles) and your sand is light, you might as well use pigments. But if the client wants a strong vibrant tone, or if your sand is dark, you likely will favor painting.

Let us know about your experiences!

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