UV rays are damaging to most materials, with its effects leading to the discoloration of dyes and pigments, weathering, yellowing of plastics, loss of gloss
and mechanical properties, while it can lead to sunburn, premature aging and even the development of potentially lethal melanomas in both humans and animals.
Therefore, if not adjusted to suit the component being coated, the oven temperature settings may lead to under cure, coating burn, poor adhesion, discolouration, loss of gloss
and other visible defects.
Perrin, et al , who related the loss of gloss
with the increase of the surface roughening for the coating systems.
Unfortunately, the chemistry of silicone alkyds precludes adequate long-term performance on the exterior of Navy surface ships, which is evident by their loss of gloss
and color fading to a light gray color within 9 to 12 months after application.
Their broad scope of performance enhancement ranges from adding protective effects such as improving heat, light and weather resistance to reduce color fading and loss of gloss
, to flame retardants with a preferred environmental and health profile for intumescent coatings, processing waxes lending functional end-application benefits and specialty ingredients such as APEO-free wetting agents, label-free dispersing agents, sugar-based neutralizing agents, as well as silver biocides for antimicrobial preservation.
ASA polymers possess inherent UV resistance, that when colored with light-stable pigments ASAs achieve long-term outdoor color retention without the need to paint, whereas similar pre-colored polymers such as ABS, HIPS (high impact polystyrene), or PVC (polyvinyl chloride) are more susceptible to dramatic color shifts accompanied by degradation and loss of gloss
and other properties upon long-term UV exposures.
The coated panels were rubbed with the cotton moist with respective solvent and observed for any softness of the film, peeling of the film, and loss of gloss
After eight years of service, a recent inspection revealed that the coating retains an excellent appearance with no fading or loss of gloss
The injury was observed in terms of the change in the color, color shade, loss of gloss
and peeling out of the film, etc.
* After 12 months less than 50% loss of gloss
, and colour change between 2 and 6 delta units (subject to the colour).
The loss of gloss
is largely due to photooxidation and hydrolysis of the coating surface followed by removal of the degraded material by liquid water, including both dew and rainfall.
Severe blistering, filiform corrosion spread of corrosion around the scribe and loss of gloss
was noticed in natural exposure testing.