Earthborn Moisture Vapour Transmission Test

A piece of testing equipment!

I had a question last week about which paint to use on a lime plastered wall that would be subject to heavy traffic. Now I had always used the official data for this answer, which was that the sd value for the Earthborn EcoPro and the Claypaint were the same at 0.2. However, being an inquisitive sort I thought that I had better check with the powers that be at Earthborn.

I was answered very promptly (as they are very good there) with the following chart. 

Product	Moisture Vapour Transmission (g/m²)
Claypaint	1115
Ecopro Matt	727
Ecopro Midsheen	481
Wall Glaze	1157

So the solution was to use the claypaint with a couple of coats of wall glaze over the top. This is especially important on the internal surface of external walls as they need to be the most breathable. Internal wall surfaces on internal walls could take the EcoPro, but I would not really recommend that Midsheen here as it is not porous enough. 

All paints will of course be fine on gypsum plastered walls, but for lime we would recommend using the clay paint at all times (unless you wish to use an alternative silicate or lime paint - Auro do an excellent white lime paint for instance) and if you need the extra protection of the glaze to make it more wipeable, then the earthborn wall glaze is a great partner to the claypaint.