Conventional building use (2/1 structure: front double coating, back single coating, the most mainstream in the market)
-Front total coating (primer+topcoat): ≥ 20 μ m (minimum requirement of national standard), market standard polyester PE: 20-25 μ m
-Primer: about 5 μ m
-Topcoat: 15-20 μ m
-Back coating (back paint): 5-8 μ m (single coating, mainly rust proof, not weather resistant)
Common film thickness for different paint systems
- Ordinary polyester PE: front 20-25 μ m, universal for roof and wall surfaces
- High weather resistant polyester HDP/silicon modified polyester SMP: front 25-30 μ m, better outdoor weather resistance
- Fluorocarbon PVDF (three coatings and two baking): front side 30-40 μ m, highly corrosive coastal/chemical environment, long warranty period
- Thickened special version: 40-60 μ m, customized for heavy-duty anti-corrosion
Classification of back coating
-2/1: Back paint 5 μ m (economical type)
-2/1M: Back paint 8 μ m (back is moisture resistant, commonly used for sandwich panels)
-2/2: Double coated on both sides, 12-20 μ m on the back, with exposed components on both sides
Key points of national standard
The average total thickness of the front coating is ≥ 20 μ m; A single measuring point cannot be lower than 90% of the nominal minimum value; Less than 20 μ m requires mutual agreement and confirmation between the ordering parties.
