Coating Faults:

The following terminologies have been extracted from BS2015 – Glossary of Paint


The description applied to a paint or varnish containing bits of skin, gel, flocculated

material or foreign particles, which project above the surface when the paint or varnish is applied in a manner appropriate to its type and purpose.

The term PEPPERY is sometimes used when bits are small and uniformly distributed.

The term SEEDY specifically denotes bits which have developed in a paint or varnish during storage.


The process of diffusion of a soluble substance from, into, and through a paint or varnish coating from beneath, thus producing an undesirable staining or discoloration.

Examples of soluble materials that may give rise to this defect are, certain types of the following classes of materials: bituminous paints, wood preservatives, pigment dyestuffs and stains.


The formation of dome – shaped or blisters in paints or varnish films by local loss of adhesion and lifting of the film from the underlying surface. Such blisters may contain liquid, vapor, gas or crystals.


A deposit like the bloom on a grape which sometimes forms on a glossy enamel, paint or varnish films, causing loss of gloss and dulling of colour. Sometimes bloom may be removed by wiping with a damp cloth.


The formation of a friable, powdery coating on the surface of a paint film caused by disintegration of the binding medium due to disruptive factors during weathering (ultraviolet light and / or moisture). The chalking of a paint film can be considerable affected by the choice and concentration of the pigment.


A defect in which a wet paint or varnish film recedes from small areas of the surface leaving ether no coating or an attenuated one.

 CRACKING: e.g. crazing, crocodiling, mud-cracking:

Generally, the splitting of a dry paint or varnish film, usually as a result of ageing. The following terms are used to denote the nature and extent of this defect.

Hair cracking: Fine cracks which do not penetrate the top coat. They occur erratically and at random.

Checking: Fine cracks which do not penetrate the top coat are distributed over the surface giving the semblance of a small pattern.

Cracking: Specifically, a breakdown in which the cracks penetrate at least one coat and which may be expected to result ultimately in complete failure.

Crazing: Resembles checking but the cracks are deeper and broader.


A drastic type of crazing producing a pattern resembling the hide of a crocodile.


The formation of a small bowl shaped depressions in a paint or varnish film.


A downward movement of paint film between the times of application and setting, resulting in an uneven coating having a thick lower edge. The resulting sag is usually restricted to a local area of a vertical surface and may have the characteristic appearance of a draped curtain, hence the synonymous term curtaining.


Not a paint defect. It is the development of a crystalline deposit on the surface of a brick, cement etc., due to water containing soluble salts, coming to the surface, and evaporating so that the salts are deposited. In some cases the deposit may be formed on the top of any paint film present, but usually the paint film is pushed up and broken by the efflorescence under the coat.


Lifting of the paint from the underlying surface in the form of flakes or scales.


The development of loosely coherent solid aggregates in pigment-vehicle dispersion.


The showing through of the underlying surface, due to the inadequate opacity of a paint film that has been applied to it.


Skipped or missed areas, left uncoated with paint.


Failure caused by the swelling of a dry film of paint or varnish when another coat is applied over it and usually manifested by a wrinkled appearance.


The pock-marked appearance, in particular of a sprayed film, resembling the skin of an orange due to the failure of the film to flow out to a level surface.


The formation of minute holes in a film during application and drying. Sometimes due to air or gas bubbles in a wet film which burst, forming small craters that fail to flow out before the film has set.


A finish in which the brush marks have not flowed out, this being the normal appearance of a paint or varnish having poor leveling properties. A similar appearance may also be produced in paint, which normally has good leveling properties, by continuing to brush the paint after the film has begin to set.


In general, the formation of a soap by the reaction between a fatty acid ester and an alkali.

In painting practice, saponification refers to the decomposition of the medium of a paint or varnish film by alkali and moisture in a substrate, e.g. new concrete or rendering based on cement, sand and lime. Saponified paint or varnish films may become sticky and discoloured. In very severe cases the film may be completely liquefied by saponification.


The development of wrinkles in a film during drying, usually due to the initial formation of a surface skin.