|
PROBLEMS
WITH PAINT BEFORE USE OR IN PREPARATION FOR USE |
| CAUSES |
CURE |
|
SETTLING OR
PRECIPITATION (RESIN KICK-OUT) |
| Wrong thinner used |
If precipitation is slight,
add proper solvent with constant agitation, or use stronger solvent. |
| Paint too cold |
Warm paint to 70-77F |
| Over reduction |
Add fresh paint to bring back |
| Reducer or catalyst added too quickly or without
sufficient stirring |
Add slowly, and stir constantly |
| Pigment or flattening agent settled |
Check bottom of can with spatula or stick before
using, and stir thoroughly |
| VISCOSITY
OR HEAVY BODIED |
| Solvent in paint will evaporate at normal
temperature and "body up" |
Use same solvent that manufacturer used to make
paint. Check viscosity with cup |
| Used improper solvent |
Use recommended solvent for thinning |
| Catalyzed material beyond paint
life
|
See directions-some products can be recovered by
adding additional paint and catalyst |
| SKINNING
OR GELLING IN CONTAINER |
| Air drying material that is exposed to air is
partially full |
Float thinner on surface of pail and seal it,
make sure container is sealed or put in new can |
| Gelled material |
Usually cannot be recovered and must be
discarded. |
| Stored at high temperature, outside, or beyond
product's shelf life |
Store inside at room temperature and use before
6 months if polyester, polyurethane, or pre-catalyzed lacquer. |
| DISCOLORATION
OR FLOATING PARTICLES |
| Presence of vapors or fumes in spray area |
Investigate fumes like ammonia or amines from
adhesives or other sources |
| Water born or acid cure react with steel parts
or oxidize aluminum spray equipment |
Use stainless steel or solvent resistant plastic
parts and liners for spray pots |
| Improper drum or pail lining comes off |
Strain paint through fine filter or cheese cloth |
| Old nitrocellulose products |
Become amber on age in can or react with steel.
Use fresh material |
| Chemical reaction to surface treatments |
Check pH of surface since acid cures can react
with alkali materials |
| FOAMING
( WATER BASED) |
| Mixing too rapid |
Mix slowly; do not shake with mechanical shaker |
| Foam trapped in container |
Use defoamer recommended |
| DEFECTS
OBSERVED DURING APPLICATION |
| CAUSES |
CURE |
| DIRT
OR SEEDINESS |
| Unclean conditions such as dust in spray room or
drying area, dirt in air or paint line, sanding operation near air in-take
of both |
Check air supply for oil and dirt by spraying
air only from spray gun at white cloth or tissue and look for staining or
dirt. |
| Resin kick out from improper thinner |
Use correct thinner |
| Paint is very cold and created seeds |
Warm material to room temperature |
| Dirt in paint |
Strain paint before use |
| Particles appear after spraying but not while
spraying the wet film |
Make sure with magnifier that it is not air
bubbles. Dip or pour paint on glass and let dry in enclosed dust free
area. Examine film when held up to light for defects. |
| DRY
SPRAY |
| Wrong solvent used |
Choose slower evaporating solvent |
| Spray
gun problems |
| Atomized air pressure to high |
Lower air pressure |
| Gun too far from surface
Spray past surface-bounce back of spray |
Hold 6-10 inches and at right angles to
surface, release trigger when gun passes target; check that spray
booth is sucking out overspray. Increase fluid pressure and check by
cutting off air to gun and adjust stream of paint to fall approx. 3
ft. from gun if gun at shoulder height. |
| Fluid pressure too low |
|
| Wrong air cap or fluid tip |
Use correct combination based on manufacturer's
guide |
| ORANGE
PEEL |
| Paint not thinned properly |
Use correct amount of thinner and slower
evaporating solvent |
| Spray
gun problems |
| Stroke to rapid or at angle |
Slow stroke and at right angle to work |
| Air pressure too low |
Increase air pressure |
| Fluid pressure too high |
Decrease fluid pressure |
| Spray gun too close or too far from surface |
Distance should be 6-10 inches from surface |
| Air temperature too hot |
Use retarder solvent |
| Overspray striking wet surface |
Avoid creating over spray or spray so that it
does not strike previously spray surface |
| SAGGING |
| Over-reduction of solvent is too slow |
Use proper amount of thinner and faster solvent |
| Paint applied too heavy |
Apply thinner coats and more passes to get film
build. |
| Cold weather or no air circulation |
Use faster thinner or raise room temperature |
| Gun too close to surface |
Hold gun 6-10 inches from surface |
| Fat edge |
Spray edges first with thin coat, then spray
piece. |
| FLOW
OR LEVELING |
| Paint too heavy |
Reduce to correct viscosity and check with Zahn
#2 Viscosity cup. |
| Solvents evaporate too fast |
Use slower solvent if higher air temperatures |
| Improper air atomization |
Adjust spray gun |
| Application too thin |
Apply material to surface by using more passes,
wet on wet. |
| Too much air movement |
Reduce draft |
| DEFECTS
OBSERVED DURING OR AFTER CURING |
| CAUSES |
CURE |
| POOR
ADHESION (TO SUBSTRATE) |
| Unclean surface or oily wood or stain |
Clean with VM&P solvent and avoid oil base
stain |
| Primer or sealer lifts from surface |
Make sure recommended sealer and top coat are
used |
| Wood sanded too smooth especially close grain
hardwoods |
Use 120 grit sandpaper on close grain and
120-180 grit on open grain or soft woods. |
| Stain comes off with sealer |
Apply thinner coat and wipe stain off |
| Stain applied too heavy or not wiped and did not
dry |
Be sure stain is dry before applying sealer |
| Higher solids coating used as sealer |
High solids need a better profile to anchor.
Avoid polishing wood when sanding and use 120 grit. |
| POOR
ADHESION ( INTERCOAT) |
| Primer or sealer contaminated |
Clean surface |
| Sealer or primer sanded too smooth |
Sand 220 to 280 grit maximum |
| Catalyzed finish dried too long between sanding
and recoat |
Check recoat window of paint and sand within 8
hours of top coat application |
| Sealer and top coat not recommended |
Use only recommended system, avoid using
supplier's sealer and another's top coat. |
| BLEEDING |
| Organic reds, yellows, oranges used in stains
have not been sealed properly |
Avoid bleeding colors; Use vinyl sealer to seal
to stop lacquer top coat from causing bleeding. Check Japan colors do not
contain bleeding pigments or dyes. |
| Certain woods contain tanins that bleed |
Seal with barrier coat. |
| BLOOMING |
| Oil from wood or stain floats to surface |
Use barrier coat to seal in oil. |
| BLUSHING
(WHITE HAZE IN FILM ) |
| Humid weather above 60% humidity |
Add up to 16 fl. oz. retarder solvent in place
of thinner |
| Paint sprayed cold |
Bring to room temperature |
| Moisture in spray equipment |
Check air line for moisture; compressor should
have air cooler to prevent water condensation. |
| BLOCKING
(OR PRINTING) |
| Insufficient drying time before packing |
Allow longer drying time or use heat |
| Too heavy film causing solvent entrapment |
Apply lighter coats or multiple passes |
| Poor drying conditions |
Change conditions by using heat or forced air |
| Improper catalyzed material |
Check measurement of catalyst |
| Catalyzed material beyond pot life |
Follow recommended time to use after catalyzed |
| BRITTLENESS |
| Paint over catalyzed |
Check measurement of catalyst. A good indicator
may be a shorten pot life |
| Paint baked at high temperature |
Check recommendation of manufacturer |
| Paint not formulated for wood |
Paint for metal are harder but do not have
elasticity of coatings formulated for wood. |
| CRACKING |
| CAUSES |
CURE |
| Excessive dry film thickness especially with
acid catalyzed materials |
Use wet film gage during application. Do not
have a dry film thickness of more than 4-5 mils with acid-catalyzed
materials or pre-catalyzed lacquers. |
| Grain or veneer cracking |
Cracking following grain shows wood is cracking
and not caused by the paint |
| Cold cracking by repeated cycles of freezing and
return to room temperature |
Paints are normally formulated to resist 10
cycles. Put painted wood in freezer for one hour and return to room
temperature for an hour and repeat 10 times to see if fresh paint will
crack. |
| CRATERING |
| Film pulls away from areas of substrate
Cratering caused by contamination from silicone, wax or oil
If no cause can be found |
Find source of contamination in sanding aids on
belts that may contain silicone or lubricants or oils or greases for
machines or spray equipment, hand creams, or polishes as possible sources
and eliminate their use by finding substitutes. You can use anti-cratering
additive but silicone will continue to cause equipment contamination and
higher amounts of additive will be needed. |
| DRYING
TIME |
| Humid weather |
Use heat or reduce humidity |
| Cold weather |
Drying area should be at room temperature |
| Oily or unclean wood |
Clean wood by solvent wipe or use barrier coat
for oily wood. |
| Oil stain prolongs drying |
Use non-oil base stains |
| No air movement |
Use proper ventilation |
| Trying to fill open grain wood with heavy coat
of sealer which traps solvent in pore |
Use filler or high solids sealer like polyester
or polyurethane to fill pore. |
| GLOSS
CHANGES OF FLAT SPOTS |
| Absorbent putty or filler that has not been
sealed causing top coat to "strike in". |
Seal wood filler or putty. |
| Not enough sealer used or sanded through
allowing top coat to "strike through". |
Carefully sand especially around the edges and
corners. |
| Material from same container changes gloss or
after a few hours of spraying changes |
Stir material at start to be sure it is uniform.
Stir after several hours if highly pigmented or high amount of flattening
agent was used which is causing settling in can to occur quickly. |
| Gloss increases with successive coats. |
The smoother the finish after sanding, the
glossier it looks with more coats. |
| HAZING |
| Incorrect thinner |
Use thinner recommended |
| Over catalyzed with acid |
Resand and recoat but test inter-coat adhesion. |
| Blushing |
See remedies for blushing |
| Water mixing with paint because of air |
Clean air line separator and bleed the line once
per shift. |
| HIDING |
| Over reduction |
Add more paint |
| Pigment has settled to bottom of can |
Stir before using and check for settling. Low
film build. Apply more paint with more passes |
| Edges show through |
Edges are too sharp so round edges by sanding |
| Color does not match standard-base color is
showing through top coat |
Apply more paint to achieve full hiding; Color
base coat same as top coat for extra hiding; organic pigments have poor
hiding and require thicker film. |
| MARRING |
| Film not completely dry |
Allow more days for drying before put in use |
| Emulsion base does not coalesce below 55F and
will not cure |
Apply at proper temperature |
| Acid and polyester coatings will not cure at low
temperatures. |
Must cross link at manufacturer's recommended
temperature range. They usually take 7 days to reach final hardness. |
| Pot life has expired |
Must use within pot life or may be able to
reactivate with fresh material and catalyst. |
| Soft film |
Mar resistant additive may help but use proper
system for intended use. Don't use nitrocellulose lacquer if you want a
hard scratch resistant film. |
| PIN
HOLING (BUBBLING) |
| Water in air atomized |
Clean air separator and drain water from line |
| Air trapped in open pore of wood |
Use a thin wash coat to penetrate pore |
| Fine bubbles after force drying |
Use adequate flash off time before using heat |
| Polyurethane bubbles carbon dioxide causing pin
pricks to appear after drying |
Urethane reacting with moisture: use retarder
and successive thinner coats. |
| Viscosity too heavy trapping air |
Thin paint
|
| Film too heavy |
Use thinner coats |
| SHRINKAGE
(WRINKLING) |
| Surface dries quicker while underlying paint
remains wet causing wrinkling |
Avoid excessive heavy coats. Force drying may
cause wrinkling. Polyester primers shrink if sanded to soon even if dry.
Allow overnight cure before sanding |
| Incompatible coating systems-solvent in top coat
attacks and softens primer. |
Use compatible systems and follow manufacturers
recommendations |
| YELLOWING |
| Exposure to UV in sunlight |
Use UV inhibitor in coating or correct paint |
| Yellow on aging |
All coatings yellow, some more than others,
aliphatic polyurethane's and acrylics yellow least; nitrocellulose
lacquers, aromatic urethanes, oil drying alkyds conversion varnishes
yellow more. |
| Exposure to strong amines |
Some coatings yellow more when exposed to
ammonia or other amine cleaning agents. |
| Yellow blotches or brown spots. |
Yellow spots can be caused by bleeding dyes or
such as hansa yellow coming to surface or oils causing staining. |
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