One coat tarmac render

[Dylan T]

Desperately need to render a front wall, but can't get someone round to sort so was looking to do myself with some grey k rend or weber. However getting my hands on anything is impossible at the moment, but I have seen this stuff from Tarmac; anyone used that before? Considering I only need grey, and providing with a test the dried natural colour of the cement was ok, does anyone know if it can be left without being painted like the mounocouche systems?

Thanks