Brushing application

The viscosity of elastomeric adhesives determines their method of application. Typically, solvent-borne rubber compounds require low viscosities for application. Thus, viscosities lower than 0.6 Pas for spray, curtain or dip applications are required, whereas for brush application viscosities lower than 5 Pa s are generally used. Roll- coating technology requires viscosities between 5 and 15 Pa s. 

Because most latices have low viscosities by compounding, most of the waterborne rubber adhesives are sprayable. Thickeners such as fumed silicas can be added to increase viscosity and thixotropy. This means that even at relatively large viscosities (over 10 Pas) many water-based rubber adhesives can be sprayed. Dip and curtain applications require viscosities between 0.05 and 0.3 Pas, whereas brush application works with viscosities between 1 and 50 Pa s. 

In the industrial world of manufacturing plants, power stations and the like, more than 80% of painting is concerned with the maintenance of existing structures and plant. Although airless spraying can be more than 20 times faster than brush application and conventional spray some four times as fast, there are many occasions where access difficulties and safety considerations prevent their use. Rollers and brushes therefore continue to be widely used. 

Rollers are available up to 450 mm wide and are at their best on large unbroken surfaces, e.g. storage tanks, pipework etc. when application rates two to three times faster than brush application are achieved. Long-pile (up to 30 mm long) rollers are particularly useful on rough or pitted surfaces. 

Brush Application of paint by brushing is still a commonly used method for maintenance painting. Coverage of large areas is slow and the quality of finish achieved relies heavily on the skill and motivation of the painter. 

A characteristic of the group (a) of resins is that they air-dry solely by solvent evaporation and remain permanently solvent soluble. This fact, combined with the need to use strong solvents, makes brush application very difficult, but sprayed coats can be applied at intervals of one hour. A full vinyl system such as (o) possesses excellent chemical and water resistance. Many members of group (o) have very poor adhesion to metal, and have therefore been exploited as strip lacquers for temporary protection. Excellent adhesion is, however, obtained by initial application of an etching primer the best known of such primers comprises polyvinyl butyral, zinc tetroxy-chromate and phosphoric acid. 

Chlorinated rubber is soluble in aromatic solvents, and paints made from it dry by solvent evaporation alone. In contrast to the vinyls, there is less difficulty in formulating systems that are suitable for brush application. It has excellent resistance to a wide range of chemicals and to water, but as it is extremely brittle it needs to be plasticised. To preserve chemical resistance it is necessary to use inert plasticisers such as chlorinated paraffin wax. Due to the presence of ozone depleting solvents, chlorinated rubber coatings are being phased out and largely replaced by vinyl acrylic coatings which have very similar performance and can be formulated from lower aromatic or aliphatic solvents. 

Brush application is very desirable for inhibitive primers applied directly to steel and for toxic materials. Roller application is not recommended for structural steel surfaces. 

In the United States creosote specification AWPA PI /89 is intended for the treatment of timber for land and fresh-water use, and the heavier grade AWPA P13/89 for the preservation of marine piling and timber. In the United Kingdom a British Standard Specification, BS. 144/90, Part 1, specifies three grades of creosote two for pressure impregnation and one for brushing application. The standards of the West European Institute for Wood Preservation (WEI) are often used in Europe. 

Turco Product Division, Purex Corporation. When combined with vapor degreasing and alkaline cleaning, this process offers very high-strength bonds on titanium. Plasa Jell is also a proprietary chemical marketed by Semco Division, Products Research and Chemical Corp. This formulation is available either as a thixotropic paste suitable for brush application or as an immersion solution for tank treatment. 

Brush marks. Lines of unevenness that remain in the dried paint film after brush application. Brush marks and ropiness are associated with poor flow and sticky application. These defects are more often encoimtered in highly pigmented products and in certain latex paint formulations. Tbo rapid recovery of consistency in a thixotropic system will also cause these defects. The remedy may be the addition of a flow promoter, reduction in consistency, or modification of the rheological properties. 

Snaith HJ, Whiting GL, Sun B, Greenham NC, Huck WTS, Friend RH (2005) Self-organization of nanocrystals in polymer brushes application in heterojunction photovoltaic diodes. Nano Lett 5 1653... 

Another animal study reported that dermal contact with coal tar creosote-treated wood produced fetotoxic effects in pregnant sows (Schipper 1961). Four sows were confined to wooden farrowing crates for 2-10 days before delivery. The platforms of the crates were coated with three brush applications of a commercial wood preservative containing 98.5% coal tar creosote. Following contact with creosote,... 

Brush applicator Intramammary syringe Spray container... 

Many of the difficulties encountered by these early investigators were related to the insistence of the paint makers that hiding power be determined in "practical" paint systems—that is, that the amount of pigment present be based upon the amount required to produce brushing viscosity in a simple linseed oil vehicle. Since pigments varied in both density and oil absorption, pigment volume concentrations were seldom comparable. The same paint makers also insisted upon a "practical" brush application and preferred visual to instrumental comparisons. 

Brush application of bonding resin consisting of glutaraldehyde (5%), HEMA (33%), bis-GMA (2%), camphorquinone photoinitiator (0.1%), water (55%), and acetone (5%), followed by light curing. 

Use Level 0.1-0.3% (on fofal formulafion, spray applic.) 0.2-0.4% (on total formulation, brush applic.)... 

Features Provides superior resist, to bubble buildup and film cratering during roller and brush applic. 

Chem. Descrip. Long oil aikyd resin in Rule 66 min. spirits/xylene Uses Aikyd for brush-applied architectural coatings such as interior and exterior house paints brushing applic. modifier for latex paints, metal protective coatings... 

Long oil epoxy ester Decorative/maintenance paints for use in harsh environments e.g. oil refineries, chemical works LAWS Brush application... 

Choice of resin is determined by the performance requirements of the adhesive, in terms of adhesive power, resistance and stability. The required evaporation rates depend on the application technique, which can vary from the rapid evaporation needed on a laminating machine to the slow drying necessary for manual brush applications. The major solvents employed are aromatic and aliphatic hydrocarbons (such as toluene, xylene and special boiling point aliphatics) and oxygenated solvents such as ethyl acetate, MEK and acetone. In many cases mixed solvent systems are used. Chlorinated solvents are found in some applications but their use is declining due to concerns over toxicity and environmental impact. Few alcohols are used in adhesives because they rarely have the solvency required to dissolve the resins. 

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