Newbie limewashing question!

[TheHat77]

I’m limewashing an internal wall. If I add casein to help with adhesion, would it affect the limewash’s breathability?

Apologies if this has been answered a million times before!

 

[a twig]

Yes it does reduce the breathability of the limewash - obviously the less you add, the less of a reductive effect it has

 

[MatthewC]

Surely if you are limewashing a breathable wall (e.g. lime plaster on limestone) then suitable wetting of the wall (damp but not running, and let it be absorbed a bit) should give you all the adhesion you need? Or are you just trying to reduce the number of coats you need? A breathable alternative is clay paint.

 

[a twig]

Usually in this case it’s adhesion of the limewash to itself I think @MatthewC - casein helps bind it all together so you can have higher lime content in each coat and thus greater opacity, and the casein prevents dusting and makes is more durable, obviously with breathability trade offs though.

When limewashing an old spot stained chimney breast I found using limewash with casein added greatly helped to hide / block the old soot stains