The fading speed can be limited to a certain extent by light stabilizers, ultraviolet absorbers and the light fastness can reach level 6 or 7, but we cannot guarantee 100% no fading, especially the brighter the color, the easier it is to fade.
Long term exposure to sunlight leads to the degradation of plastic
materials. The complete solar UV spectrum ranges between 280 and 400 nanometers, but the most aggressive part is the UVB range with very short wavelengths between 280 and 315 nanometers. UV radiation represents only 4.6% of the solar spectrum but causes the most important damage to the polymeric materials. This is call photo-degradation, a process that generally results in breaking down the polymer chains. This frequently results in a deterioration of the physical properties, changes in color or chalking of the part surface. The irradiation is the radiation energy incident over a specific area for a given period of time. It is expressed either in W*s /m2, Joule/m2 or very often in Langley (Ly).
1 Ly = 1Cal/Sq.cm = 4.185 Joule/SQM
The global annual sunlight radiation level (kLy/year) for various
countries is given in the table below. values in this table are only indicative. In some large countries including China, radiation levels can vary significantly from one area.
Region
|
kLy
|
Region
|
kLy
|
Region
|
kLy
|
Region
|
kLy
|
Austria
|
80
|
El Salvador
|
140
|
Luxembourg
|
80
|
Russia(North)
|
70
|
Afghanistan
|
180
|
Ethiopia
|
140
|
Libya
|
180
|
Russia(South)
|
140
|
Alaska
|
70
|
Finland
|
70
|
Madagascar
|
140
|
Sardinia
|
20
|
Algeria
|
160
|
France
|
120
|
Mali
|
200
|
Saudi Arabia
|
200
|
Angola
|
120
|
Germany
|
80
|
Malta
|
160
|
Senegal
|
180
|
Argentina
|
160
|
UK
|
70
|
Malaysia
|
140
|
Sicily
|
140
|
Australia
|
180
|
Greece
|
120
|
Morocco
|
160
|
Singapore
|
140
|
Bahamas
|
140
|
Guatemala
|
140
|
Mauritania
|
180
|
South Africa
|
160
|
Bahrain
|
200
|
Guyana
|
120
|
Mexico
|
160
|
Span
|
140
|
Belgium
|
80
|
Haiti
|
160
|
Mozambique
|
160
|
Sudan
|
220
|
Burma
|
120
|
Honduras
|
140
|
Nepal
|
160
|
Suriname
|
120
|
Bolivia
|
140
|
Hungary
|
80
|
Netherlands
|
80
|
Sweden
|
70
|
Brazil
|
120
|
India
|
180
|
Nicaragua
|
140
|
Switzerland
|
80
|
Bulgaria
|
100
|
Indonesia
|
140
|
Niger
|
200
|
Taiwan
|
140
|
Canada
|
100
|
Iraq
|
180
|
Norway
|
70
|
Thailand
|
140
|
Chad
|
200
|
Iran
|
180
|
New Zealand
|
120
|
Tunisia
|
160
|
Chile
|
140
|
Israel
|
180
|
Omen
|
160
|
Turkey
|
140
|
China
|
140
|
Italy
|
120
|
Pakistan
|
180
|
Uruguay
|
160
|
Columbia
|
100
|
Jamaica
|
160
|
Panama
|
40
|
US North
|
100
|
Costa Rica
|
140
|
Japan
|
100
|
Paraguay
|
160
|
US Arizona
|
180
|
Cuba
|
140
|
Jordan
|
180
|
Peru
|
140
|
US Florida
|
140
|
Cyprus
|
140
|
Kenya
|
140
|
Philippines
|
140
|
Uganda
|
140
|
Denmark
|
70
|
Kuwait
|
180
|
Poland
|
80
|
Vietnam
|
140
|
Egypt
|
200
|
Korea
|
120
|
Portugal
|
40
|
Venezuela
|
160
|
Ecuador
|
120
|
Lebanon
|
180
|
Romania
|
100
|
Zambia
|
180
|