Temporary coating

Uses Acrylic for clear or pigmented peelable coatings, extremely low VOC coatings, spray booth coatings, temporary product proteclanls, and paint masks... 

Uses Dispersant anti-resoil agent for carpet shampoo and carpet mfg. surfactant in floor polish, powd. coatings, temporary coatings ink additive... 

For construction," OSHA has ventilation regulations for tunnels and shafts, compressed air, preservative coatings, temporary heating devices, and welding and cutting. 

The original Polacolot negative had water-coated intedayers of gelatin (60). The SX-70 and Polacolot 2 negatives use as intedayers a combination of a polymeric latex with a water-soluble polymer. A key development was the constmction of lattices that function as temporary batnets, reducing interimage problems. The water-soluble polymer functions as a permeator, so that the harder properties ate tunable (61). 

Typical of the temporary or manufacturing aid coating systems is the RISTON dry film photoresist for printed circuit (PC) board fabrication. This was the first of these systems developed. The RISTON product stmcture and the basic steps in its use are shown in Figure 2. It consists of a photopolymer sheet laminated between a Mylar cover sheet and a polyolefin separation sheet. It is manufactured as a continuous web (see Coating PROCESSES, survey), and is suppHed in roUs of varying width and photopolymer composition. 

In addition, all of the process raw materials must be clean and not iatroduce contaminants. The raw materials and temporary coatings must also be defect-free, and these have to be manufactured under similar conditions so that no contaminants are iatroduced. The solvents used to clean the substrate and develop the resists must be filtered and pure. Care must also be taken to ensure that no trace compounds or elements are present that may affect the electronic properties. The specific type of coating aid, the type of functional coating, and the process used to apply the functional coating are all widely varied ia actual practice. 

Resists. Resists are temporary, thin coatings appHed to the surface of the copper-clad laminate. After patterning, these films act as masks that are chemically resistant to the cleaning, plating, and etching solutions used to define the circuit traces of the PWB. Both nonphotosensitive and photosensitive types are used. 

There are obviously situations which demand considerable over-design of a cathodic protection system, in particular where regular and efficient maintenance of anodes is not practical, or where temporary failure of the system could cause costly damage to plant or product. Furthermore, contamination of potable waters by chromium-containing or lead-based alloy anodes must lead to the choice of the more expensive, but more inert, precious metal-coated anodes. The choice of material is then not unusual in being one of economics coupled with practicability. 

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