Paint coatings continued spraying

PROTECTIVE COATING. A film or thin layer of metal glass of paint applied to a substrate primarily to inhibit corrosion, and secondarily for decorative purposes, Metals such as nickel, chromium, copper, and tin are electrodeposited on the base metal paints may be sprayed or brushed on. Vitreous enamel coatings are also used these require baking. Zinc coating are applied by continuous bath process in which a strip of ferrous metal is passed through molten zinc. 

Two coats of these paints were applied 5 h apart over a heavily chalked latex paint on a white pine board. Because significant differences have been seen between individual chalky test substrates, common control paints containing unmodified HASE, (hydroxyethyl)cellulose (HEC), and HEUR thickeners were included in each test. Test paints were dried for 18 h at 25 BC and 50% relative humidity and then placed in a fog box for 5 h. (The fog box is a Plexiglas (poly(methyl methacrylate)) box with six spray nozzles on the inside top that continuously spray a fine mist of water over the painted panels placed about 15B off the vertical in racks about 10 in. (1 in. z 2.54 cm) below the nozzles.) We used two different fog boxes one sprayed deionized water and one sprayed tap water. 

CAS 21645-51-2 EINECS/ELINCS 244-492-7 Uses Filler, flame retardant, smoke suppressant for thermoplastics, thermosets, FRP spray-up/hand lay-up, FRP continuous panel, adhesives, sealants, mastics, paints, coatings, paper, elastomers, and rubber prods. Features High loading med. grind high in superfines Properties Ground particulate 11 p median particle diam. 98% thru 325 mesh sp.gr. 2.42 bulk dens. 0.7 g/cc (loose) surf, area 3-4 mVg oil absorp. 27-28 brightness (TAPPI) 88 ref. index 1.57 hardness (Mohs) 2.5-3.5... 

Even small traces of certain corrosion stimulants, notably soluble chlorides and sulphates, can maintain a continuing corrosion process under a paint film because the salts accelerate the initial dissolution of ferrous iron (and other metal ions) but are not immobilised in the hydrated oxide corrosion products. Filiform corrosion is the most spectacular example of this phenomenon, but progressive spread, preceded by blistering, is also observed from scratches or other breaks in a coating, for example during salt spray tests. 

Safety No year goes by without some widely used chemical being declared suspect on toxicity grounds. The paint industry has responded rapidly to eliminate toxic chemicals from coatings or to show how they can be used safely in an industrial environment. Examples are the elimination of specific ether-alcohol solvents and the introduction of air-fed hoods for spraying isocyanates. Of particular interest in corrosion prevention is the current pressure to eliminate chromate pigments. Currently there are no equally effective alternatives and the emphasis has had to be on safe usage. The search for replacements continues. 

When the solubility of the thermoplastic is poor at room temperature it may be possible to produce a dispersion in a mixture of diluents and latent solvents. This dispersion may be applied by conventional paint spray equipment. The coated item is placed in an oven where the diluents evaporate off. The latent solvents then dissolve the thermoplastic and evaporate from this solution at a controlled rate, thus producing a continuous him. P.V.F., and p.v.d.f. and p.t.f.c.e. coatings are produced from dispersions of this type. 

Specification for electroplated coatings of 65/35 tin/nickel alloy Method for the evaluation of results of accelerated corrosion tests on metallic coatings Methods of test for paints Cross-cut test Pull-off test for adhesion Resistance to artificial weathering (enclosed carbon arc) and Addendum No. 1 Resistance to continuous salt spray Notes for guidance on the conduct of natural weathering test... 

The salt water immersion test (SWI) and the standard salt spray (fog) test (SS) were conducted for both ISPCs and control baking enamels applied on bare CRS, iron phosphated B-1000, and BD+P60 panels. The painted coupons of about 1.0 mil dry film thickness cured at 163 C for 15 minutes were X-cut through the film to the substrate and then either immersed in a 3% NaCI solution (SWI test) or subjected to a continuous salt-solution spray in a test chamber (SS test). After a specified duration of testing, the specimens were removed from the salt solution, and the coated surface was immediately dried. A DUCK brand tape (Manco, Inc., Westlake, OH) was applied over the X-cut and then removed, and the protective performance was... 

Coat n. Paint, varnish or lacxjuer applied to a surface in a single application (one layer) to form a properly distributed film when dry. A coating system sexually consists of a number of coats separately apphed in a predetermined order at suitable intervals to allow for drying or curing. It is possible with certain types of material to build up coating systems of adequate thickness and opacity by a more or less continuous process of application, e.g., wet-on-wet spraying. In this case, no part o the system can be defined as a separate coat in the above sense. 

---