3. Preparation of Coatings
A. Mixing of Materials
(1) Mix base component with catalyst as follows:
NOTE: Use clean containers for mixing. Do not use containers lined with organic coatings.
(a)
Use 1 part of X-310A with 2 parts 683-3-2 by volume, adding catalyst to base while stirring base component.
(b)
Mix thoroughly to ensure uniform distribution.
(2) Immediately after mixing affix a label to the container, stating date and hour of mixing, and date and hour of pot life expiration. See paragraph 3.B.
B. Handling and Storage
(1) Catalyzed coating material has a shop (usable) pot life of 4 hours at 70°F. Scrap any catalyzed coating material whose shop life has expired. Use of coating, which has exceeded its shop pot life, will seriously affect its performance in service, although this is not readily apparent at the time it is applied. Store uncatalyzed coating at a temperature of between 40°F and 90°F. Shelf life of uncatalyzed coating is 12 months from date of manufacture.
4. Application of Coating
A. Clean all surfaces in accordance with paragraph 2, prior to coating application.
B. Apply coatings in a well-ventilated area maintained at a temperature above 65°F and with a relative humidity of less than 85%. Brush or spray apply to a thickness of 1 to 2 mils (0.001 to
0.002 inches).
C. Apply coating on surface to be coated and overlap a minimum of 1/4 inch to ensure a fluid-tight barrier. For edge sealing decals apply coating to cover 1/4 inch of both decal and adjacent surface.
5. Cure of Coatings
A. Cure for four hours at 65°F (minimum) prior to outdoor exposure.
B. Complete cure requires 14 days at 65°F (minimum).
6. Rework and Repair
A. Damaged coatings shall be cleaned and coated per paragraphs 2., 3., 4., and 5.
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51-21-61 Page 702 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Feb 15/73
CONDUCTIVE COATING SYSTEM FOR EXTERIOR REINFORCED PLASTIC SURFACES -CLEANING/PAINTING
1. Equipment and Materials
A. Conductive Coating - BMS 10-21
B. Abrasive paper - 240 grit or finer
C. Cheesecloth
D. Tape - Masking, aluminum foil adhesive and polyethylene film
E. Probe - Film resistance measuring F70328-1 (for fasteners)
F. Probe - Surface resistively measuring ST895A-3
G. Multimeter - Simpson P/N 269-2
H. Solvent - Aliphatic naphtha
I. DC meter (500,000 ohms maximum)
J. Aluminum foil strips (at least two)
2. Apply Conductive Coating
WARNING: SOLVENTS AND PAINT MATERIALS CONTAIN TOXIC AND/OR FLAMMABLE INGREDIENTS. CONSULT INDUSTRIAL HYGIENE, FIRE, AND/OR SAFETY ORGANIZATIONS ON FACILITIES, EQUIPMENT, VENTILATION, AND OTHER REQUIREMENTS FOR SAFE SOLVENT CLEANING OPERATIONS.
A. Clean and prepare surface (Ref 51-21-21).
B. Agitate each conductive coating component thoroughly prior to mixing to ensure homogeneity.
NOTE: Conductive coating is supplied in two-component kits consisting of base and catalyst.
C. Mix conductive coating per manufacturer's instructions.
NOTE: Stamp containers with time and date. Mixed material has a usable pot life from time of mixing of 4 ± 0.5 hours at 75 ± 5°F. Do not use material whose pot life has expired.
D. Allow mixed material to stand undisturbed for at least 1/2 hour.
E. Mask all areas not to be coated with conductive coating.
WARNING: DO NOT USE PAINT SYSTEM OR PAINT CONTAINING METALLIC PARTICLES ON ANTENNA FAIRINGS. ANTENNA PERFORMANCE WILL BE IMPAIRED.
F. Apply conductive coating by spray or brush to dry film thickness of 0.6 ± 0.2 mil.
G. Cure conductive coating.
(1)
Allow coating applied to countersunk areas to dry at least 20 minutes before installation of fasteners.
(2)
Allow coating to dry per Fig. 701 before taking resistance measurements.
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Feb 01/95 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 51-21-71 Page 701
H. Measure the conductive coating resistance.
(1)
Examine the mating surfaces of the structure and the fairing panel.
(a) Make sure all mating surfaces are clean and free of any contamination or painting.
(2)
Apply the corrosion preventative compound to all of the mating surfaces of the airplane structure that touch the wing-to-body fairing panels.
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