Powdering is always a sign that the paint was applied a little bit too thickly or too quick in succession.
Lime wash paints do interact with the wall material it comes in contact with. For easy application and a consistent look an even absorbency of the surface is important. The right absorbency also ensures that powdering or a dusty surface is not happening when the paint is applied a little bit too thickly.
If you had the lime paint applied over an ordinary white emulsion it is particularly important not to over-apply the paint, as the surface has next to no ability to absorb the lime wash paint. Too much paint on such a surface can lead to powdering or a dusty surface.
In most cases that can be fixed by letting the existing layer fully dry, allow at least 24hrs, longer is also fine.. Then, stir up any remaining or additional paint and apply one more quick, but thin coat across the entire surface. Apply wet-in-wet in free loose strokes.
If you painted directly over ordinary emulsion paint:
For surfaces painted with ordinary emulsion it is best to first apply one coat of BAUWERK Prep Coat. BAUWERK Prep Coat is not a primer or an ordinary white paint that is sometimes applied as a ‘Mist-Coat’. Instead, it provides a fresh new surface with the right amount of absorbency for the following two applications with lime wash paint.
BAUWERK Prep Coat can be rolled on and 1 liter (1 quart) is enough for 64,58ft².
If you want to try to rectify the wall and repaint with lime wash using the prep-coat as a base:
1 lightly sand across the entire surface to remove any excess paint (you don’t have to remove all of it, just the top layer)
2 remove the dust and finish with a damp cloth
3 apply one coat of Bauwerk Prep-coat by roller (one liter(one quart) will cover 64,58ft²)
4 finish with two coats of lime wash paintUsually, another quick application (nice and thin, let the bristles do the work…) of Bauwerk Paint will fix that problem.