Surface or hairline cracks can appear due to settlement, age or movement of structure.
It can also appear due too fast air dried plaster or high clay content.
Surface cracks will appear on film surface and might lead to paint failure.
Allow newly plastered surfaces to cure properly before application of primer and top coat.
New buildings might require early maintenance due to settlement and uncured painted plaster.
Remedy
Open cracks, remove efflorescence, loose and flaking paint.
Allow to dry until moisture content is below 15% measured with an ultrasonic meter or over 5% with a pin-type meter, apply PlasterSeal, PlasterPrime or DampCure to stabilize surface.
For plaster repair use HydroKey cement additive.
For a water barrier homogeneous slurry mix 5ℓ HydroKey, 7.5Kg sieved plaster sand and 2.5Kg Portland cement.
As additive to plaster mix or tile cement, HydroKey may be diluted up to 1:1 with water.
Apply undiluted to substrate when used as a keying agent, allow to air dry before application of new plaster or gypsum mixed with HydroKey ratio.
Spot prime with PlasterSeal or PlasterPrime & repaint entire surface.
