Causes:
Wax bleed causes the discolouration sometimes seen on
painted hardboard siding. It occurs when wax or
petrolatum, which is used to make hardboard siding
moisture resistant, migrates to the surface. Once there,
it changes the appearance of a coating, giving it a
"wetting" effect or a tendency to retain dirt.
Contributing factors include:
Because of their tendency to absorb heat, dark paints will
show discolouration more readily.
Areas lacking adequate coats are more likely to stain.
Because of their porosity, paints containing low levels of
binder are more likely to allow wax migration from
hardboard.
Exposure to direct sun and heat will accelerate wax bleed.
Solution:
In order to correct discolouration, you must first
identify if the problem is wax bleed.
To do so, place a few drops of household bleach on the
discoloured area. If there is no whitening or bleaching on
the surface, the stain is probably wax.
You can also place water droplets on both normal and
discoloured areas. Water will bead up and run off over a
wax film.
Clean discoloured areas with a detergent solution if
surface wax is light.
In severe cases, clean the surface thoroughly with a
solvent, such as mineral spirits.
Allow surface to dry before painting. |
