(h)
If the layer is rough, use the sand paper lightly on the primer coat with 180 grit or finer abrasive paper before you put on the coating again.
(i)
Clean the surface with Toluene or Xylene to remove the dirt.
S 377-005
(4) Mix and Apply the Erosion Coating
NOTE: The erosion coating is supplied in Astrocoat kit 7100.
____
(a) Shake the base material fully.
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(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
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747-400 MAINTENANCE MANUAL
Add the catalyst to the base at the maximum ratio of 40 ml (1.3 fluid ounce) catalyst for one quart of base.
NOTE: Carefully not to have more than this ratio.
____
Mix the base.Put the label on the container immediately after you mix, with the information on the date and time when you mix and the expired time of the pot life
NOTE: The pot life at 75 |5°F is 4 hours from the time you
____ mix. Discard the material of the pot life which is expired.
If you use spray gun to apply the coating, mix with the thinner as it is necessary to get a viscosity of 27 to 29 seconds measured with a No. 2 Zahn cup.
NOTE: The maximum ratio of the thinner is one part by volume
____ of thinner to three parts by volume of base.
If you use a brush to apply the coating, it is not necessary to have the thinner.The coating mixture does not need to dry before you can apply the coating.Apply one coating by brush or spray gun to get a wet layer thickness of 0.8 to 1.5 mils (0.5 to 1.0 mil dry).Let the coating dry sufficiently, for when you touch the coating, there will not be the coating on the fingers and the fingerprint will not be on the coating. The coating must be lightly tacky.
NOTE: The dry time between the coating procedure is
____ approximately 1.5 hours at 40 to 50% relative humidity and 70 to 75°F.
Apply more coatings as it is necessary to get a dry film thickness of 10 to 14 mils.
NOTE: You must complete the coating procedure and try not to
____ have intermittent time if it is possible. If the intermittent time between coats is more than 4 hours, the last coat before the intermittent time must not be catalyzed. You can start the coating procedure again after 8 to 18 hours at 40 to 50% relative humidity and 70 to 75°F; but the coating before the intermitten time must stay lightly tacky. If the coating is not tacky, start the coating again with solvent, Series 94 (AMM 20-30-94/201).
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747-400 MAINTENANCE MANUAL
(k) If you stop the coating procedure, and the coating before is not tacky, start the coating procedure again with solvent, Series 94 (SOPM 20-30-94), refer to "Prepare the Surface" task.
NOTE: You can have bubbles during cure if the coat is too
____ heavy, or if the dry time is not sufficient between the coats.
(l)
If small bubbles occur in the coating, let the cure time be longer between the coating and decrease the coating thickness.
(m)
If you continue to have bubbles in the next two coating procedures, remove the coating refer to "In Process Correction of Damaged Rain Erosion Coating - Major Damage" task.
(n)
Start the coating procedure again.
(o)
If big bubbles occur in the coating, remove the coating refer to "In Process Correction of Damaged Rain Erosion Coating -Major Damage" task.
(p)
Start the coating procedure again.
S 377-006
(5) To cure the erosion coating, do the steps that follow:
(a) Cure a minimum of 8 hours at the usual cure conditions (70 to 75°F and 40 to 50% relative humidity) after you apply the final coating.
NOTE: If the temperature is less than 70°F or the humidity is
____ less than 40%, you will need a longer time to cure the coating.
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