Sagging
The downward flow of a paint or powder that is applied too heavy or onto a hot surface.
Salt Spray Test
Corrosion test using salt laden moist air in an enclosed chamber, the air can be acidic. This test is used as a common method for expressing corrosion resistance of a coating system.
Sand Blast
Blast cleaning using sand or an abrasive to remove corrosion by impact. Sand blasting is a dangerous process banned in many countries. Other blast abrasives such as iron, steel or aluminium are recommended.
Saponification
* Alkaline hydrolysis of fats to make soaps.
* Test for coating resistance to an alkaline environment.
* Hydrolysis of an ester by an alkali.
Scale
Rust occurring in layers, commonly found on hot rolled steel
Screen Mesh
The filter used to seperate large powder particles and contaminants from usable powder. A screen mesh is used in powder production after grinding and in powder reclaim systems application equipment.
.
Screen Mesh Size
The mesh number of a screen designates the openings per square inch or the wire.
Soils
Foreign matter on a part of the substrate to be cleaned in a pre-treatment system.
Solids
Non-volatile portion of the coating material.
Solution
Mixture formed when one material is dissolved into a liquid.
Solvent
Liquid or blend of liquids used to dissolve or disperse paint. A true solvent is a liquid that can dissolve the paint resin.
Solvent Wash
Cleaning using a degreasing solvent or mixture of solvents (often referred to as "gun wash")
Specific Gravity
Sg. An expression of density of a material relative to the density of water (always classed as 1) A typical powder coating has a sg of 1.5 - 1.8. Mileage of a powder coating is affected by sg. high sg = low mileage.
Specular Gloss
Mirror like reflectance, gloss measured at a specific angle.
Spray Chamber
An enclosure that surrounds the pre-treatment process and contains the spray cloud.
Spray Pattern
Configuration of the spray leaving the powder gun.
Storage Stability
The ability of the coating to maintain uniform physical and chemical properties subject to the manufacture'rs specification (time and temperature).
Striping
An area of light or heavily applied powder seen on the component as a stripe. An indication that the automatic application equipment needs to be adjusted or that a gun is blocked and not spraying enough powder.
Stripper
Chemical or mechanical method of removing the coating from the substrate.
Stroke
A single pass with a spray gun in one direction.
Substrate
The part being coated.
Surface Appearance
Generally refers to the smoothness and gloss of the final cured film, and/or the presence of defects or contamination.
Surface Defects
Flaws in the surface of the coated parts.
Surface Preparation
Operations necessary to prepare the surface or parts prior to the application of the coating.
Surface Tension
A property prossessed by liquid surfaces whereby they appear to be covered by a thin elastic membrane in a state of tension, the surface tension is measured by the force acting across the unit length of the surface. The phenomenon is due to unbalanced molecular cohesive forces near the surface.
Surfactant
A chemical used to adjust the surface tension between two mediums.
Surge
* A rise in pressure in an electrical circuit.
* A sudden burst of powder from a spray gun.
Suspension
Mixture of fine particles of any solid with a liquid or gas that does not settle out.