B

Barrier coat
Coating used to isolate a coating system from the surface to which it is applied or from a previous coating. Permits to increase adhesion or to insure compatibility.

Benard Cells (extended definition)
Coating defect caused by evaporation: polygonal cell patterns, micro-separation in the film due to surface tension gradients. This defect occurs in paints with low viscosity, fast solvent and high film thickness.

Binder
Non-volatile portion of the vehicle of a coating which holds together the pigment particles.

Biocide
Material or additive added to greatly delay or stop the growth of bacteria. Protects liquid paints, dry coatings and production sites from biodegradation.
See Preservative

Biodegradation
Changes caused by micro-organisms (bacteria, algae, fungi): viscosity loss, odor spoilage, delamination, discoloration...

Bituminous Coating
Coal tar or asphalt based coating material usually used in thick films.

Bleaching
Coating defect: fading of a color induced by exposure to chemicals or ultraviolet light exposure.

Bleeding
Coating defect: diffusion of pigment from a lower coat of paint into an upper coat. This diffusion causes a color change.

Blistering (extended definition)
Coating defect: formation of blisters in coating by the local loss of adhesion and lifting of the film from the underlying substrate.

Blocking agent
Additive which can block polymerization catalysts.

Blooming
Coating defect: haziness of coating surfaces caused by the exudation of a component of the coating such as oil plasticizer, or noncrosslinked coating constituent when the coated part is exposed to a cycle of heat, humidity, and cooling.

Blushing
Coating defect: whitening (milky appearance) of the surface of a coating caused by rapid solvent evaporation or the presence of excessive moisture during the curing process.

Bodying agent
Additive which controls wet film thickness and allows thick layer applications.
See Thixotropic agent

Bonding
Attachment between a coating film and the surface to which it is applied.

Boxing
Mixing of coatings by pouring from one container to another.

Bridging
Formation of a coating film over a depression.

Brittleness
Lack of resistance to cracking or breaking of a coating when bent or flexed.

Brush marks (extended definition)
Coating defect: strikes left after application of the paint by a brush. Due to poor flow, levelling or substrate wetting. Frequent defect of latex paints or highly pigmented solvent-based paints.

Brushability
Capability of a paint to be easily applied by brush (without brush-marks). Brushability is influenced by paint rheology and open time.

Bubbling
Coating defect: bubbles of air or solvent vapor in the applied film. This defect can be temporary or permanent.

Build
Wet or dry film thickness of a coating.

Buffer
Additive which maintains a required range of pH in aqueous compositions.
Syn. pH-stabilizer

Bumps
Coating defect: high and low spots in a coating surface caused by unwanted flowing that occurs during curing. Caused by surface tension gradients that arise during curing.