Frosting

Frosting

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A white, salt-like substance on the paint surface.  Frosting can occur on any paint color, but it is less noticeable on white paint or lighter tints. On masonry, it can be mistaken for efflorescence (see Efflorescence and Mottling).

Possible Causes:                                                                                              

  • Forms mostly in protected areas (such as under eaves and on porch ceilings) that do not receive the cleansing action of rain, dew and other moisture.
  • Use of dark-colored paints that have been formulated with calcium carbonate extender.
  • Application of a dark-colored paint over a paint or primer containing calcium carbonate extender.

Solution:

  • Frosting can be a stubborn problem. It often cannot be washed off readily. Moreover, the condition can recur even as a bleed-through when a new top coat is applied. In extreme cases, it can interfere with adhesion.
  • The best remedy is to remove the frosting by wire brushing masonry or sanding wood surfaces; rinse, then apply an Rainbow Paints alkyd-based primer before applying a coat of Rainbow exterior paint.
Foaming / Cratering

Foaming / Cratering

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Formation of bubbles (foaming) and resulting small, round concave depressions (cratering) when bubbles break in a paint film, during paint application and drying.

Possible Causes:

  1. Shaking a partially filled can of paint.
  2. Use of low quality paint or very old acrylic paints.
  3. Applying (especially rolling) paint too rapidly.
  4. Use of a roller cover with wrong nap length.
  5. Excessive rolling or brushing of the paint.
  6. Applying a gloss or semi gloss paint over a porous surface.

Solution:

   1.   All paints will foam to some degree during application; however, higher quality paints are formulated so the bubbles break while the paint is still wet, allowing for good flow and appearance.

   2.  Avoid excessive rolling or brushing of the paint or using paint that is more than a year old.
Apply Rainbow gloss and semi gloss paints with a short nap roller, and apply an appropriate
sealer or primer before using such paint over a porous surface. Problem areas should be sanded before repainting.