Paint coatings continued forms

A feature of rust, particularly of magnetite (which is an electronic conductor) is its ability to reduce oxygen to a far greater extent than does the metal (Evans and Taylor, 1972). Thus, once some rust has formed, corrosion may be accelerated. This is also one reason why, if all rust is not removed from a metal surface before application of a protective paint coating, corrosion continues under the film. Similarly, akaganeite residues on meteorites promote corrosion under the conditions of ambient humidity and this leads to disintegration of such meteorites in museums (Buchwald and Clarke, 1989). 

The latices that result from the emulsion polymerization find immediate application as adhesives, paints, coatings, or in the processing of leather. For this, control over the distribution of the latex particles is desired. If emulsifier and water are added at the beginning of the polymerization and monomer and initiator are added continually during the course of the polymerization, then only those latex particles initially formed will continue to grow. The latex particles are relatively small and show a narrow distribution of size. If, on the other hand, just one part of the initial sample is polymerized and the rest is added as an emulsion during polymerization, then new latex particles will be produced. Since the particles formed first are very large and those formed last remain relatively small, the distribution of sizes becomes very wide. 

A continuous intact film of water-resistant paint forms an effective electrical resistance to the flow of a corrosion current (a resistance of over lO flcm through the film is easily achieved). Underfilm corrosion can then only occur if a channel of electrolyte connecting anode and cathode can be established by local adhesion failure between the coating and the metal substrate. 

Extrusion coating is ideal for rods, tube and wire. The article is passed through a paint reservoir and then out via a die, which leaves only the correct thickness of paint in place. There are further techniques suitable for flat articles in sheet or web form. Knife coating is ideal for very thin coats, especially on continuous paper or plastic webs. The knife is either a metal doctor blade or a curtain of high velocity air (an air knife) directed onto the surface and it removes surplus material applied previously. 

The first paints were based upon linseed oil (obtained from flax). This is an unsaturated long-chain triglyceride, which, with metal activators, crosslinks via radical pathways to form a continuous film on the substrate. Modern paints use synthetic polymers together with either a solvent or suspending medium (e.g., water), which evaporates leaving the deposited film. Exceptions are powder coatings, which require heat for completion. 

Because of their ability to form relatively thin continuous films in conjection with their hydro-phobic nature, waxes are used extensively as a protective coating, primarily as water/moisture barriers. Most common example of this is in the use of household wax paper . This material is usually used to wrap sandwichs so that the bread and filling do not dry out. Here it is desired to keep the moisture in. Waxes are also applied in the emulified form to the exterior painted surface of our automobiles. They are utilized to prevent both water/moisture and air from contacting the painted surface. Such barriers prevent oxidation and prolong the life of the painted surface... 

VIKON FGT forms a clear, continuous film of high resistance to abrasion on fabrics and can be used for coating colored yarn fabrics for slip-covers, etc. It is also an excellent latex for making water based paints for painting awnings, tarpaulins, etc. The coating formed has high resistance to submersion under water. 

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