Surfaces previously finished in water paint should not be washed down nor rubbed down wet, as this may weaken the adhesion. Wherever possible, the preparation should consist of dusting down, coupled where necessary, with dry rubbing down.
If the existing finish is in good condition the new paint may be applied directly upon it.
A stage is reached however, when the number of coats and the thickness of the film is so great as to affect adhesion to the initial coating even when the surface appears sound.
If any doubt exists as to the number or quality of the previous coatings, the work should be primed with an Oil based Sealer / Primer to bind down and increase stability.
On old coatings which are in bad condition, loose and flaking material must be scrapped off, the edges feathered with suitable filler, and the surface coated with an Oil Primer / Sealer.
Surfaces previously finished in size-bound distemper must be thoroughly washed off and sponged to remove all traces of powder and size. When dry, the surface is then primed with an Oil Primer / Sealer.
On surfaces painted with emulsion paints, where the existing paint is in good condition the water paint may be applied directly. If in bad condition, all loose materials should be scraped off and the surface bound down with an Oil Primer / Sealer.
Surfaces previously finished in oil paint are not suitable for decoration with water paint.