Painting problems & solutions with Gary Lonnen from the Dulux Decorator Centre in Torrox Costa.
Efflorescence is caused by the crystallisation of salts found in building materials such as bricks. It appears either as patches of fluffy crystal or as a hard shiny film. Paint should not be applied until the efflorescence has ceased to appear and has been removed.
Remove fluffy efflorescence deposits with a coarse Hessian sacking, or by dry brushing. Repeat the process every few days until no more appears.
Hard shiny efflorescence should be well sanded to roughen the surface. It can then be painted over. On new buildings it is advisable not to use conventional solvent based paints such as gloss or eggshell for at least 12months. This allows the surface to dry out thoroughly.
It is essential that an Alkali Resisting Primer be used prior to application of any solvent- based finishes.
Alternatively water based masonry paint can be used such as Dulux Weathershield.
2.Flaking/Blistering of Paint on Exterior Masonry Surfaces
The most common cause of flaking or blistering is moisture beneath the paint film.
In addition flaking or blistering can occur if the paint was applied over dirt, oil, grease
or other form of surface contamination
Another common cause is if the surface was not adequately prepared and was still powdery and friable when painted.
Scrape back to a firm edge all areas of poorly adhering coating.
Abrade shiny surfaces with abrasive paper. If previous the coating was a solvent based masonry paint or gloss finish, then it will be necessary to re-paint with either a solvent based paint again or Weathershield All Seasons Masonry Paint. Stabilising Primer should then be applied to all the prepared problem areas then over coated with exterior masonry finish. Stabilising solution should not be applied to sound, new or bare surfaces.