TM55-1500-345-23
Triggering. Proper triggering of the gun is
ery of the discrepancy. Areas painted prior to the
c.
discovery of such discrepancies must be
difficult to learn and can only be developed by
practice. It is a matter of judgement and
inspected and remedial measures taken when
necessary. Brushing and roller coating on certain
sensitivity of touch and variations of triggering
surfaces must be used in confined areas. Reme-
technique may be called for in special situations.
In general. the painter should begin his stroke
dying incorrect applications, however. also calls
for training. The practice of allowing inadequately
before triggering the gun and release the trigger
trained personnel to apply MI L-C-46168 coatings,
before stopping the stroke. It is intended to
feather out the end of a stroke so that the end of a
particularly to aeronautical surfaces. is unauthor-
ized and dangerous. Unusual or unsuitable cli-
succeeding overlapping stroke will blend into it.
matic and atmospheric conditions are normally
Examine of correct techniques are shown in figure
not a problem since manual spray painting must
be accomplished in an approved facility which
NOTE
usually compensates for such conditions. Unsuit-
able or faulty equipment can only be remedied by
A reasonable amount of care will main.
obtaining proper equipment or repair. Table 3-1
tain spray guns and spray equipment in
shows common troubles of spray coating
top operating condition and prevent a
operations with suggested remedies or methods
majority of spraying difficulties. Thor.
of avoidance.
ough cleaning immediately after use
and appropriate lubrication of equip-
Faulty spray patterns and suggested
b.
ment are essential. Care should be
corrections are shown in Fig 3-5.
taken to not allow gelling to occur for
any particular mixed batch of plural
Blushing of coatings is the result of water
c.
component paint. The system should be
condensation from the atmosphere within, or on,
purged and flushed after use of each
an applied organic film. It occurs when the
mixed batch to avoid system stop.
temperature of the work surface falls below the
pages, and batch mixes.
prevailing dewpoint. (It shall always be looked for
Setting Spray Pattern. See Fig 3-4 for
in production coating whenever other than aver-
d.
recommended adjustments.
age atmospheric conditions prevail). It shows as a
lighter-than-normal or bleached discoloration or
3-11. P A I N T I N G DIFFICULTIES AND
increased opaqueness of the film. It may occur to
REMEDIES.
the extent that a surface powder develops which
can be removed by fingernail or by light rubbing.
a.
Coating troubles may be divided into six
(Rubbing will not cure the condition). It may be
groups: (1) Inadequate surface preparation (in-
almost imperceptible, and blushing inducing con-
cluding temperature), (2) incorrect methods or
ditions may escape notice on test panels sprayed
techniques of application, (3) unusual and unsuit-
prior to production coating due to the temperature
able climatic and atmospheric conditions, (4)
differences between test and production environ-
unsuitable and improperly adjusted equipment, (5)
ment. Though MI L-C-46168 painted items are not
faulty finishing material or improperly mixed or
susceptible to water or moisture damage immedi-
agitated components and (6) systems not purged
ately after proper application to items. Great care
of previously mixed materials. An experienced fin-
must be taken to avoid surface condensation prior
isher may be capable of adjusting to obtain proper
to coating or water induction, in any form, into
results with faulty materials, but this is an emer-
unmixed components or the mixture prior to or
gency measure only and must be with the cogniz-
during application. Water will not affect the cure
ante and authority of the quality control facility.
process after proper application. Water will affect
The practice is not advised. Incorrect methods of
paints other than plural component catalytic
application should be discontinued upon discov-
paints.
