Prime Coats

Prime Coats

 

materials that form the undercoats of paint and varnish coverings. The principal purpose of the prime coats is to provide durable adhesion between the outer (covering) layers and the surface being painted. In addition, they may perform other functions, including the protection of metal from corrosion, the enhancing of wood grains, and the covering of pores and other defects of the surface being painted. Prime coats are made from natural or synthetic, liquid or solid film-forming substances—drying oils and al-kyd. urea-formaldehyde, and epoxy resins. The hard film-forming materials are used in the form of concentrated solutions and dispersions in organic solvents or water. Many prime coats contain pigments (iron oxide, red lead, or zinc chromate) and sometimes fillers (talc, mica, or chalk).

Prime coats are applied with a putty knife or by spraying. The thickness of prime coats is 10–100 microns (0.01-0. 1 mm). Dried prime-coated surface is covered by paint or lacquer.

REFERENCES

Beliaeva. K. P., T. V. Todorova, and N. G. Shtan’ko. Lakokra-sochnye materialy dlia otdelki izdelii iz dereva. Moscow, 1971.
Spravochnik po lakokrasochnym pokrytiiam, 2nd ed. Edited by M. M. Goldberg. Moscow. 1974.
References in periodicals archive ?
Top Coat Technology--This includes prime coats for offset, flexo, inkjet, Indigo, and color laser printing, as well as barrier coats, tie coats, and weather resistant coatings.
Prime coats are not considered structural applications.
OCAPE reported that some paving personnel believe that prime coats limit the amount of mix sliding during compaction of HMA over aggregate base but that mix crawl was more related to mix formulation and that prime alone would not eliminate the phenomenon [10].
According to ASTM-D8-02 standard terminology relating to materials for road and pavements, a prime coat is "an application of a low-viscosity bituminous material to an absorptive surface, designed to penetrate, bond, and stabilise the existing surface and to promote adhesion between it and the construction course that follows"
1) The Asphalt Institute describes a prime coat as "a spray application of a medium curing cutback asphalt or emulsified asphalt applied to an untreated base course".
After the drying process, each mold should be checked for damaged parts, such as broken gates of joints of buckled of spalled prime coats, and further investigated to what causes damage.
To achieve optimal mold cavities for casting, the wax assembly should not allow wax to be trapped when the mold is dewaxed There should be no sharp edges, undercuts, bubbles, negatives or rough surfaces that could form sharp or weak features in the prime coat.
For each dip applied, the slurry application should be uniform, and each prime coat should be examined for each mold and all subsequent coats.
It was shown that multiple prime coats increase the extent of this hot deflection.
The primary cause of scabbing is delamination of the prime coats and the backup dips.
Prime coat buckling defects usually occur on flat surfaces as an island of surplus metal, and normally have hairline fins associated with them, usually at a casting's edges.
Environmental Conditions - Temperature and humidity fluctuations in the dip and drying area, after prime coat application, cause expansion differentials between the wax and the slurry dip.