In terms of field applied, they are now available in water-based,
acrylics and thermoplastics with ultra-bonding, cross-linking chemistry and
acrylic elastomerics Bottom line is that
the same solar reflective IR pigment technology is used and high levels of
reflectivity are available, color-for-color as in the factory applied paints.
These field-applied coatings clean up with water, are very low toxic and have a
higher overall thickness once they are fully dried. However, in order to bond
to failing, older Kynar coated metal roofs, some manufacturers are now making
specialized “hot” primers, that meet the
VOC requirements and adhere very well to the older coated metal. The acrylic colored IR coatings can be
applied over this bonding primer and stick very well. It is common with some manufacturers to also
to have a clear sealer put on over the finished coloured reflective coating in
order to protect the colour coat further, just like the similar purpose clear
sealers commonly used on automotive finishes.
This clear coat or “glaze coat” further adds to the dirt shedding
quality of the steep-slope, metal roofs.
When full water-proofing is also required for the metal
roof, a class of flexible, waterproofing coatings called “elastomerics” is
required to seal the metal roof as a whole system.
