Technical data
Table 5-2. Allowable Coating Thickness for Production Level Finishing (Depot, Original Manufacture, Field)
Coating Specification Number of Coats
Dry Film
Thickness Range (inches)
(1)
Minimum
(2)
Maximum
(2)
MIL-PRF-23377 and MIL-PRF-85582
Epoxy Primers
One coat 0.0006 0.0009
To Be Reactivated
(3)
0.0004 0.0013
Mist, “Light Dust Coat” Activation 0.0002 0.0005
After Reactivation, Total 0.0006 0.0009
Two coats 0.0008 0.0020
TT-P-2760 Elastomeric Polyurethane
Primer
One coat 0.0010 0.0015
Two coats 0.0012 0.0025
MIL-PRF-85285 High Solids Polyure-
thane Coating
One coat (without cross coat) 0.0017 0.0023
One or two coats (with cross coat) 0.0016 0.0050
Three to four coats
(4)
0.0048 0.0070
MIL-PRF-22750 Topcoat One coat 0.0008 0.0020
Two coats 0.0016 0.0040
MIL-C-27725/SAE AMS-C-27725 Fuel
Tank Coating
Two coats 0.0008 0.0012
(1)
In most cases the desired coating thickness should be the low to nominal for the range specified unless there is a
requirement for thicker coatings. The higher end of the range is not intended to be the mean or average of thickness
measurements (unless it is required) but to allow for overlaps, etc., that occur in localized areas or sections of a part
or surface. Measurements should not be taken around edges or holes and considerations must be allowed where
overlap occurs such as in angles and on irregular surfaces.
(2)
Lower end of thickness range is expected when painting detail parts and small assemblies. Mid to high end of thickness
range is often needed when finishing large areas such as the exterior of aircraft.
(3)
A single coat which is to be reactivated with a ″light dust coat″ before topcoat application after scuff sanding.
(4)
This coating thickness is intended for use only in specific areas where wear or abrasion are a factor, such as leading
edges. These unique requirements should be specified in finish documents.
5.6.6 Inspection Control. Inspection shall enforce the
requirements of this technical manual.
a. Proper and adequate equipment shall be used at all
times.
b. Materials shall be thoroughly mixed with thinners and
catalysts properly proportioned.
c. Ensure that thorough cleaning and proper preparations
are taken prior to application of each coat, proper drying
times are observed before recoating, and coatings are
applied at the proper thickness.
d. Ensure the general appearance, texture, color, and gloss
are acceptable. No sand paper finish to exceed approxi-
mately 320 grit coarseness, wrinkling, crazing, blister-
ing, fisheye, lifting, or pitting/cupping as defined in this
technical order is permissible. To exceed limits of
Paragraph 5.6.6.2.6.
5.6.6.1 Certain physical tests shall be made before, during,
or after coating operations:
5.6.6.1.1 Water Break Test (refer to Paragraph 3.1.9).
5.6.6.1.2 Spray Test Panel (refer to Paragraph 5.5.4).
5.6.6.1.3 Coating Thickness Measurement (refer to Para-
graph 5.6.2).
5.6.6.1.4 Adhesion (Wet) Tape Test. This method covers a
procedure suitable for establishing acceptability of intercoat
and total surface adhesion of an organic coating system.
5.6.6.1.4.1 Adhesion tests shall be made on the completed
exterior finish system after drying for a period of at least 48
hours in a sufficient number of selected areas to ensure a
satisfactory level of adhesion for the overall finish system.
5.6.6.1.4.2 To perform this test, wet a piece of cloth/gauze
pad with either tap or distilled water and cover with plastic
TO 1-1-8
Change 3 5-11