Lefflorescence

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  • Efflorescence consists of soluble salts formed on the surface of plaster or brickwork by the evaporation of water. They usually show as loose white powder or as feathery crystals. Occasionally they appear as a hard glossy deposit covering and penetrating the surface. Efflorescence can occur on internal as well as external surfaces and is often a mixture of different deposits.

These salts may have come from:

  • The brickwork,
  • Soil in contact with the brickwork,
  • Contamination with seawater or spray.

Efflorescence may damage plaster and paint if these are applied before the walls have dried out.

While efflorescence persists it is unwise to apply paint. Persistent efflorescence indicates abnormal water penetration of the brick and plasterwork.

Any faults in construction must be corrected, i.e. leaking water pipes, faulty damp-proof courses.

Substrate:

Masonry, gypsum plaster.

Solution:

    • No remedy is available for Efflorescence; the only way to prevent it from occurring is to prevent damp from entering the structure that will allow efflorescence to occur. Once it has occurred, allow it to dry out (less than 15% moisture contents) and scrub the crystals off with a nylon or wire brush. Should the efflorescence reoccur, continue to brush the affected area.
    • When no more efflorescence has appeared prime the affected area with Rainbow Fresh Plaster Primer and allow drying for 24 hours.
    • Then apply the selected Rainbow Paints topcoat.

Fading Tips

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  • Subjective term used to describe the lightening of the color of a pigmented paint following exposure to light, heat, time, temperature, chemicals, etc.
  • The observed fading may result from deterioration of the pigment, the vehicle/binder, or from a decrease in gloss.
  • A separation of the vehicle from the pigment particle in the interior of the film, with the subsequent introduction of micro voids which scatter light, may also be interpreted visually as fading.

Substrate:

Masonry, gypsum plaster, masonite/hardboard, woodwork, metal, polystyrene, galvanized iron or concrete tiles.

Solution:

  • Abrade the surface with a detergent solution and a scrubbing brush, and rinse off with clean water and allow 24 hours for drying.
Lapping

Lapping

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Appearance of a denser color or increased gloss where wet and dry layers overlap during paint application.

Possible Causes:

  1. Failure to maintain a “wet edge” when painting.
  2. Use of a low solids “economy” paint.

Solution

  1. Using a Rainbow  pure acrylic paint makes it easier to avoid lapping problems because higher solids (pigments and binder) content makes lapped areas less noticeable. If substrate is very porous, it may need a primer/sealer to prevent paint from drying too quickly and reducing wet edge time. Alkyd paints generally have superior wet edge properties.
  2. If substrate is very porous, it may need a primer/sealer to prevent the paint from drying too quickly and reducing wet edge time.
  3. Alkyd paints generally have superior wet edge properties.