Description:
Color loss and overall
deterioration of paint film on fresh masonry, concrete or stucco.
Possible Cause:
• Stucco and mortar
joints contain hydrated or "hot" lime, a dry compound added to improve the
workability of these materials. Different mortars are compounded with
different amounts of "hot" lime, depending on the end use of the mortar.
This pro b l e m is then made worse by more "hot" lime being added at the
job site.
• The alkalinity of fresh or new mortar, cement mixes and concrete is
expressed numerically by pH readings. The pH of fresh cementitious materials
is 13 to 14. It takes approximately 30 days for fresh cement materials to
drop to an approximate pH of 9. A pH of 9 is less alkaline than a pH of 13,
and a coating has a greater assurance of success when applied to a less
alkaline surface.
• Once these cement walls are cured, the introduction of moisture into these
walls will reactivate the high pH alkalinity, resulting in efflorescence,
blistering and peeling of the paint film.
Solution:
• When damp areas are
found on surfaces, the source of moisture intrusion must be repaired. The
surface should be prepared by removing chalk, efflorescence and damaged
paint film, and must be thoroughly dry before applying new paint.
• Both new and aged unpainted walls must be clean and free of moisture and
efflorescence. (See EFFLORESCENCE for description and resolution).
• Paint products must be chosen with care.
Recommended
System:
Primer
1 Coat of
FLEX BON #194 Series Exterior 100%
Acrylic Latex Primer
Topcoat
2 Coats of Top Quality FLEX BON Exterior
Latex Paint |
