Glossary

A - Z list of keywords and terms from the coatings industry.

S

Salt Spray

Accelerated Weathering test to assess corrosion resistance by exposing item to a fine, salt solution mist.

Sand Blasting

Method of preparing steelwork by shooting aabrasives (sand / grit) at very high pressure onto the surface.

Sand Mill

A form of vertical bead mill, in which the coating, pre-dispersed on a high speed mixer, is pumped through a tube packed with beads rotated by a central agitator. The tuber is cooled by water to keep the temperature controlled.

Saponification

Formation of a soap-like substance caused by chemical attack of an alkyd caused by alkali and moisture in a substrate.

Screen Printing

A printing process in which the ink or varnish is forced by a squeegee through fine holes in a flat or cylindrical mesh to form the image to be printed.

Settling

Layer or residue of material at the bottom of a coating.

Shelf Life

Maximum period of time that a material may be stored and remain in a usable condition.

Sieving

The process of removing sold and semi-sold impurities from a liquid coating by use of a sieve.

Single Roll Mill

A form of dispersing equipment, little used now, in which the coating was fed around a rotating steel roller and into a tight 'nip' formed by a steel bar held against the roller.

Sinkage

Loss of gloss level due to the coating being absorbed into the underlying coating or material.

Skinning

A potential fault for air drying paints and inks if their top surface dries in the can or when exposed during normal use. Anti-skinning additives are used to control this, and Litho ink manufacturers may float an anti-skinning solution on the surface of the filled ink pot, or evacuate the air in the space above the ink prior to lidding.

Sleepiness

A loss or lack of gloss as a coating dries.

Solar Reflecting

Coating used to reduce the absorption of heat onto a surface.

Solvent

Although water is sometimes a solvent for certain resins, usually refers to an organic liquid in which resins may be dissolved and which evaporates readily to the atmosphere leaving behind a film or coating.

Solvent Based

A coating system in which the resins are dissolved in non-aqueous solvents.

Solventless

Coating that is free of all solvents.

Soya Oil

The oil extracted from the soya bean, it is less yellow than linseed and forms an important constituent of alkyd resins.

Spot Colour

The litho process often uses a 'process set' of four inks, for which most colours can be mixed on the paper by using the amounts of ink determined by the colour separation made for each of the four plates involved. Whilst this works very well for pictorial work, designs which use solid colours are better reproduced using a special plate and ink - a spot colour - for that colour.

Spraying

The process of coating a surface by breaking up a coating into small particles (in the case of a liquid coating, by forcing it through a fine nozzle) which are then directed, possibly with the help of a current of air or an electrostatic charge, onto the surface.

Squeegee

The flexible blade used to force the ink through a screen in screen printing.

Stay Fresh Ink

Ink formulated so that it will not cross-link if left open for a few hours (overnight, for example) on a litho press.

Stove

To use heat, particularly in hot air ovens, to cure coatings.

Substrate

The surface onto which a coating system is placed, and to which it adheres.

Surface Tension

Cohesive strength of a coating.

Syneresis

Oil / Resin visble on coating surface due to pigment settlement in container.

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