Term
| chalking failure appearance |
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Definition
*surface soft and powdery
*easily removed by wiping surface |
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Term
| erosion failure appearance |
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Definition
*surface removed on high spots and brush marks to base coating or primer.
*similar to chalking |
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Term
| checking failure appearance |
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Definition
*surface phenomenon
*uneven, small, noncontinuous fissures in coating which do not penetrate to the substrate. |
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Term
| alligatoring failure appearance |
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Definition
*very large macrochecking
*cross-hatched pattern |
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Term
| cracking failure appearance |
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Definition
*small breaks in coating to substrate
*may be linear, cross-hatched, or curved
*cracks may or not be continuous |
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Term
| mud cracking failure appearance |
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Definition
*large macrocracking
*coating may curl at cracks and lose adhesion |
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Term
| wrinkling failure appearance |
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Definition
*furrows and ridges in coating surface
*may be linear or random pattern
*wrinkle may be fine or quite large |
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Term
| biological failure failure appearance |
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Definition
*softening or slime reaction of coating
*blotchy brown or black spots on coating surface causing poor, dirty appearance |
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Term
| discoloration failure appearance |
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Definition
| *yellowing, greying, or darkening of coating |
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Term
| inorganic checking failure appearance |
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Definition
*usually fine visible or microscopic checks
*don't penetrate to the substrate |
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Term
| inorganic mud cracking failure appearance |
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Definition
| *fine to fairly large segments (1/4 in.) flaking from surface |
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Term
| inorganic pinpoint rusting |
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Definition
*pinpoint spots of corrosion progressing from a few per square feet to almost continuous.
*early failure can be catastrophic |
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Term
| Cause of failure Chalking |
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Definition
*surface disintegration by actinic rays of sun on the organic resin binder
*improper pigmentation |
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Term
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Definition
| *chalking mechanism w/ coating surface removed by weathering |
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Term
| Cause of failure checking |
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Definition
*surface stress
*caused by shrinkage due to weathering and continued surface polymerization and oxidation |
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Term
| Cause of failure alligatoring |
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Definition
*internal stress where surface shrinks more rapidly than body of coating.
*hard topcoat applied over soft undercoat. |
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Term
| Cause of failure cracking |
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Definition
*stress
*due to continued polymerization and oxidation
*improper pigmentation |
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Term
| Cause of failure mud cracking |
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Definition
| *rapid drying of highly filled coatings |
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Term
| Cause of failure wrinkling |
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Definition
*surface reaction
*surface of coating expands more rapidly during drying than does the body of the film |
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Term
| Cause of failure biological failure |
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Definition
*biodegradation of the coating by bacteria or fungi
*coating used as source of nourishment |
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Term
| Cause of failure discoloration |
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Definition
| *resin or pigment color change due to weather or chemical action |
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Term
| Cause of failure inorganic checking |
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Definition
*zinc pigment to binder ratio is high
*rapid drying conditions cause surface checking |
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Term
| Cause of failure inorganic mud cracking |
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Definition
*application of coating too heavy
*rapid drying conditions |
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Term
| Cause of failure inorganic pinpoint rusting |
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Definition
*zinc pigment mask by other pigmentation
*improper zinc/binder ration
*uneven coating thickness |
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Term
| Select coating formulated w/ radiation-resistant resins (acrylics) & noncatalytic, nonchalking pigments |
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Definition
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Term
| Select chalk-resistant coating w/ good flow out to a smooth film |
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Definition
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Term
| Select coating formulated w/ weather-resistant resins & inert reinforcing pigments in addition to noncatalytic colored pigments. |
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Definition
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Term
*apply thin coats & thoroughly dry before adding additional coats.
*never apply hard topcoats (epoxy) over soft undercoats (asphalt) |
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Definition
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Term
| Select coating formulated from nonreactive weather-resistant resins, reinforcing pigments, and nonreactive colored pigments |
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Definition
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Term
*use coatings w/ strong adhesion
*apply coatings under proper drying conditions and prevent sags, puddles, or areas of excess thickness |
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Definition
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Term
*choose coatings w/ even, thorough drying characteristics
*apply evenly; avoid excessive thickness |
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Definition
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Term
*select oil-base coating which contains permanent fungicides or bacteriacides
*nonoil coatings should use nonbiodegradable modifiers |
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Definition
| biological failure remedy |
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Term
| select coating formulated w/ both color stable resins and pigments |
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Definition
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Term
*formulation should include reinforcing pigments
*apply coating as thin as recommended
*second coat, if necessary
*apply under favorable drying conditions |
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Definition
| inorganic checking remedy |
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Term
*apply coating at no more than recommended thickness
*apply under favorable drying conditions |
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Definition
| inorganic mud cracking remedy |
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Term
*usual remedy:remove coating and reapply more satisfactory zinc coating
*apply maintenance coat at first sign of pinpoint failure |
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Definition
| inorganic pinpoint rusting remedy |
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Term
*are used to measure dry film thickness.
*A coating thickness gage provides vital information as to the expected life of the substrate, the product's fitness for purpose, its appearance and ensures compliance with a host of International Standards.
*post cure |
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Definition
| tooke/ elcometer thickness gauge |
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Term
*measure coating viscosity
*Application |
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| surface profile micrometer |
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