Mid-coats in the industrial coating is mainly barrier coats applied over the primer, most commonly known as undercoats, body coats or Intermediate coats.
A mid-coat or undercoat is a coat of paint that is applied before the final or topcoat of a paint system.
Similar to a primer, mid coats also provide a protective film to the base.
It is used to fill any minor imperfections to create a smooth, even-coloured surface ready for the application of the topcoat
The mid-coat must adhere to primers to build up the paint system. Coatings that build up a high thickness of the paint per coat are often termed “High Build coatings”.
Mid-coats are specially designed to enhance the overall protection and, when highly pigmented, decrease permeability to oxygen and water.
The undercoat is applied over the primers to further prevent the water from passing into the film and leaching out the inhibitive pigmentation, as without it there would be no passivation
In any paint system, the colours should be contrasting hence the colour should be lighter than the final topcoat to allow good hiding by the topcoat.
Mid coat – Industrial Coating
Mid coats are often coloured white or grey. Hence, applying it over the surface provides an even base and neutral colour to paint over with your selected shade.
Another reason for using a mid-coat is the improved pore filling. Mid-coats should have high mechanical strength and good covering power hence, a good base for the topcoats.
Mid-coats or Undercoats must remain compatible with finishing coats when there are unavoidable delays in applying them.
An undercoat is a layer of paint that is used to prepare a surface before the topcoat is applied
The Principal Purpose of Mid coat – Industrial Coating is as follows:
- Mid-coats are mainly barrier coats
- Have strong chemical resistance.
- Provides strong cohesion.
- Ideal for good adhesion of the topcoat.
- Resistance to moisture vapour transfer.
- Increase electrical resistance for the coating system.
- Strong bonding to primer and topcoat.
- Mid-coat gives a good body for sanding and provides a key for the topcoat.
- It’s anti-chemical and corrosion.