TASK 70-18-01-330-801
1 . General.
CAUTION:
DO NOT USE SOLVENTS CONTAINING HALOGENS WITH TITANIUM OR TITANIUM ALLOY PARTS.
A.Masking method with chemical maskant can be used for protection of parts against the corrosive action of solutions containing acid, alkalines or cyanide.
B.The maskant protection for the parts can withstand temperatures of 210°F (100°C).
2 . Equipment.
Subtask 70-18-01-330-001
C.The following equipment is required for the application of this process:
(1)Efficient ventilation system for extracting and neutralizing vapors.
(2)Oven capable of maintaining the maskant manufacturer's recommended curing temperature.
3 . Materials.
Subtask 70-18-01-330-002
 
Consumable Product
No.
 
A. Solvent
 
(1) Acetone
C04-003  
 
(2) Methyl-Ethyl-Ketone
C04-001  
 
B. Maskant
 
(1) Turco 522
C01-152  
 
(2) Turcoform Mask 537-42
C10-014  
 
(3) Turcoform Mask 537
C10-014  
 
(4) Turcoform Mask 540-R
C10-014  
 
C. Tape, Masking
 
(1) Scotch No. 470, tape
C10-067  
4 . Procedure.
Subtask 70-18-01-330-003
D.For optimum uniformity in adhesion and performance, the parts to be masked must be free of oil, grease, dirt or corrosion. Clean parts thoroughly per TASK 70-21-03-160-001, Cleaning Method No. 3 - Steam Cleaning or TASK 70-21-22-110-801, Cleaning Method No. 22 Light Duty Aqueous Cleaning. Special care must be taken to clean the threads. Parts must be fully dry and at approximately room temperature before masking.
E.Apply the masking tape listed in Subtask 70-18-01-330-002 or equivalent as follows:
(1)Mask the areas that will be exposed to stripping and cleaning solutions.
NOTE:
Chemical maskant will be peeled off from these areas with the help of masking tape.
(2)Mask all openings for sealing purposes.
(3)Mask the thermal sprayed areas that will not be exposed to stripping and cleaning solutions.
NOTE:
Applying masking tape underneath the chemical maskant prevents the penetration of chemical maskant into the thermal spray.
F.Mix and adjust the viscosity of the chemical maskant by following manufacturer instruction sheet for the maskant listed in Subtask 70-18-01-330-002, Materials.
G.Alternative Procedure Available. Slowly immerse the part into one of the maskants listed in Subtask 70-18-01-330-002, Materials. Do not dip a part rapidly into the maskant, as this introduces air and creates bubbles in the film. Slowly remove the part from the maskant and drain the remaining maskant from the part for at least three minutes.
NOTE:
The viscosity of the chemical maskant will increase if the container is kept as open to the air. Pour out of a sufficient quantity of chemical maskant into a clean smaller container. This prevents a change in viscosity of the remaining material in the original container.
G.A.Alternative Procedure. Apply one of the chemical maskants listed in Subtask 70-18-01-330-002, Materials, by brushing slowly. Use a natural bristle paint brush.
H.Allow part to dry until the film is tack free.
I.Repeat Subtask 70-18-01-330-003, paragraph 4.D. and paragraph 4.E. until a minimum of three coats have been applied.
J.Air-dry to cure maskant for a minimum of four hours or air-dry for two hours minimum and oven cure for 30 minutes minimum, at 195-210°F (90-100°C).
CAUTION:
DO NOT REMOVE TAPE FROM OPENINGS ON PART.
NOTE:
Use a scribing knife (cold or hot) with conductive blade tip and feedback circuit to detect and notify the operator of either substrate contact or proximity. This can prevent the risk of scratching the part.
K.Trim the maskant by cutting along the edge of the masking tape and around areas to be processed. Expose only the area to be processed by peeling away tape and maskant but do not remove the tape or maskant from the openings.
WARNING:
CLEANING SOLVENTS ARE FLAMMABLE, VOLATILE, AND TOXIC. THEY SHOULD BE USED WITH ABUNDANT VENTILATION. AVOID PROLONGED BREATHING OF VAPORS AND REPEATED OR PROLONGED CONTACT WITH THE SKIN OR CLOTHING.
L.Use one of the solvents listed in Subtask 70-18-01-330-002, Materials, to remove any maskant or tape that does not readily peel away.
5 . Quality Assurance.
Subtask 70-18-01-330-004
M.Check that the masked area is evenly covered and free from voids or pinholes.