Coating Reference Handbook - Hempel

HEMPEL
CHECKPOINT PAINT TEMPERATURE P 28
WHY?
A too high paint temperature during application may lead to dry spraying
and thus poor film formation of the coating, with premature rusting
as a consequence. Also a too high temperature will result in a dramatic reduction
in two-component paints pot-life.
A too low temperature will lead to high viscosity making the paint difficult to
stir up properly and impossible to atomize correctly. Overthinning may be
the painters solution, resulting in slow drying and poor sagging resistance - and ­
consequently too low dry film thickness being applied, with premature rusting
and fouling as a result.
CORRECTIVE ACTIONS:
Areas with dry spray and poor film formation due to high temperature must
be scraped or sanded to remove dust spray,and applied an extra coat. It is very
important that the extra application secures a uniform film, free of pinholes.
In severe cases remove damaged coating by blasting.
Areas with sagging may be ground and together with areas with too low dry film
thickness must receive extra coats of paint to bring the dft up to the specified.
PREVENTIVE ACTIONS:
For too high temperature look for possibility for sheltering or cooling. Find
if possible suitable amount of thinning, even if this exceeds datasheet
recommendations slightly. However always use recommended thinner.
For too low temperature, take paint into heated room in sufficient time before
application to get it heated (24 hours suggested). Do not bring it out to the
application site until last minute before it is to be used.
HOW TO DETECT:
Thermometer.
Optimum paint temperature for most paints is 15-25°C.
Solvent-free paints already has a very short pot-life.
At high temperatures >25°C, it may be necessary to cool
down the paint in a reefer container before the application
process.
INSPP28 ed1 28/07/95 EMi