Technical data

on MIL-C-81706/MIL-DTL-81706 solution immedi-
ately after rinsing the MIL-C-38334/SAE AMS-1640
compound from aircraft surfaces which are to be painted
and while these surfaces are still wet. Allow the gross
amount of rinse water to run off the aircraft, but do not
wait for completed drying before applying MIL-C-
81706/MIL-DTL-81706 solution. The oxide film just
removed by MIL-C-38334/SAE AMS-1640 compound
will reform during this time period and prevent a proper
formation of the MIL-DTL-5541 conversion coating
from the MIL-C-81706/MIL-DTL-81706 solution.
b. Wet or flood the surface to be treated and keep the
surface completely wet with the solution until coating is
formed. This will take from 1 to 5 minutes depending on
the surface condition, the particular manufacturer’s
product being used, and the temperature. Begin appli-
cation at the lowest surface then apply sideways and
upward to prevent streaking.
c. On areas where difficulty is experienced in getting the
coating to take (coating formation), light abrading with
a very fine or fine aluminum oxide nylon abrasive mat,
specification A-A-58054, Type I, Grade B, soaked with
the solution will help overcome the difficulty. If the
surface is dirty, remove the dirt with the nylon mat or
sponge. The mat or sponge used to remove the dirt
should be rinsed in clean water and squeezed almost dry
before wetting with stock coating solution for reappli-
cation.
d. It will be noted during the initial coating application that
there will be a tendency for dark (brown) spots to form
on some areas. The formation of these spots can be
prevented to some extent by lightly rubbing with the
fingers (gloves on). If the spots are allowed to form, the
applicable areas shall be abraded with the nylon mat to
remove the stain, and a fresh coating shall be reapplied.
e. After controlling the stain formation, discontinue agita-
tion, apply additional solution to keep all surfaces wet
and observe the aluminum surface for a color change.
The aluminum will turn a brassy, yellow or iridescent
greenish tint, which is easily detected through the
overlying solution.
f. Do not let the coating over-develop, or surface powder-
ing will be experienced. Disturb such areas by rubbing
with fingers (gloves on) or nonabrasive nylon mat as
necessary.
g. When coating formation shows on all areas, stop the
reaction by rinsing or flooding the area with fresh clean
water. The reaction of the solution is stopped by diluting
the acid component. Be careful not to flush the solution
into areas where it cannot be removed or further diluted
by water. Accidental spills in confined areas can be
neutralized using baking soda followed by rinsing with
clean water.
h. Allow the surface to drain or pick-up the excess water
by absorbing in a sponge by blotting action; do not rub.
Excess rubbing will remove the coating since it is soft.
i. Areas not properly coated (including those that are
powdery) shall be recoated by reapplying fresh coating
solution, abrading lightly with a nylon mat (nonabrasive
or fine abrasive), allowing normal time for coating to
develop, rinsing, and drying.
j. The coating should be allowed to air dry for 2 hours
minimum or, if required, speed dried by blowing dry
with warm clean air (140° F maximum) for 1 hour prior
to using a part or painting.
NOTE
• Check with Bioenvironmental Engineer and
Environmental management for proper dis-
posal of excessive solution.
• The final protective paint system or primer
shall be applied only on a completely dry
surface and shall be applied within 48 hours
after application of MIL-DTL-5541/MIL-C-
81706/MIL-DTL-81706 conversion coating.
The reapplication of MIL-C-38334/SAE
AMS-1640 corrosion removal compound and
MIL-C-81706/MIL-DTL-81706 chromate
conversion coating is mandatory if more than
48 hrs has elapsed since the previous
application.
TO 1-1-8
3-12 Change 3