Painting

Kaehr's capabilities are limited to wet (solvent based) and dry (powder) processes. There is a tremendous number materials that can be applied, depending on the characteristics that the customer wants from the finish. The most important step insuring good adhesion of these finishes is surface preparation. Mechanical (for instance sand blasting) and or chemical pretreatment (chromate or phosphates) is used to insure that the coating meets or exceeds all specification requirements. Included in our painting capabilities are solid film lubricants, low outgassing materials for vacuum or space projects and silicone based materials for high temperature applications.

Wet Paint

Since the advent of powder coating, sometimes referred to as dry paint, solvent based paints are sometimes called wet paint. Standard solvents are water and petroleum based. Some materials cure as the result of the evaporation of the solvent from the paint base. Current environmental standards concerning air quality have favored those paints which use a minimum of solvent, a low VOC solvent, or water as the solvent. Multi-component paints such as polyurethane and certain epoxies require a base, a catalyst and occasionally a solvent. These paints do not 'dry' in the conventional sense, but rely on a chemical reaction between the components to harden. Baking enamels do not develop a full cure until the paint has been baked. These exhibit the appearance and feel of porcelain. The variety of paint types used today is tremendous, each formulated for a specific application or work environment. It is important to consult with a paint manufacturer or applicator, such as Kaehr, to see that the material applied to the product is of the proper type.

Wet paint can be applied by brushing, dipping, or spraying. Spray guns used today have been modified to minimize 'overspray'. HVLP (High Volume Low Pressure) spray guns deliver paint at lower pressures than the older conventional spray equipment, thus minimizing the atomizing effect of the spray gun. Pressure pots and high pressure applicators atomize the paint at the spray nozzle without the addition of pressurized air. Electrostatic spray guns use paint that has had the conductivity increased and then gives it a static charge. The paint is then attracted to the surface being painted and less paint is wasted as overspray.

Powder Coating

As air quality concerns grew in the late 1960's, dry paint, or powder coating grew in popularity. Since no solvents are used, the paint must be cured by a baking operation which essentially fuses the paint particles into a homogeneous film. The dry paint is applied using a special electrostatic gun. Textures and special effects can be obtained by mixing powders that have slightly different melting temperatures or flow characteristics. One of the largest construction jobs in history, the building of the Alaska pipeline, highlighted the versatility of this type of coating when it was used to coat the large pipe. The bake temperatures required, pose some limitations on certain materials but this is still a very economical means of finishing.

Solid (Dry) Film Lubricants

Solid film lubricants were originally developed to replace traditional petroleum based lubricants (oil, greases) in applications where these could cause contamination. They are used widely today as a break-in lubricant for items such as pistons or gears, sometimes in the addition to other lubricants. Some are used in high vacuum atmospheres (such as satellite hardware) because of their low out-gassing characteristics, or in high temperature applications where petroleum based lubricants could not function. Many fasteners today are coated with solid film lubricants for making assembly easier and to act as an anti-siezing compound. They are usually applied by dipping, brushing and spraying. Some require a bake cycle to develop the full potential of the lubricant. By far the most common ones contain graphite, molybdenum disulphide and fluorocarbon, either individually or in combination.

Special Coatings

This classification we use to describe those types of coatings that are used for very specialized purposes. An example would be silicone/RTV used as an ablatable coating to protect spacecraft from burning up when re-entering the earths atmosphere. Other materilas are used to provide an electrical insulationg material on conductive surfaces, while some types of electrically conductive coatings are used to provide EMI shielding on electrical instruments.