Swab Etching Procedure and Cleaning [CFML]

TASK 70-27-00-910-811-A
Swab Etching Procedure and Cleaning

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	BOTTLE - SAMPLE, STERILE
No specific	1	PAPER - TISSUE

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CPNCL02069)	LINT-FREE COTTON CLOTH
No specific	ALUMINUM ALLOYS ETCHANT S1096
No specific	CARBON STEEL ETCHANT S1095
No specific	STAINLESS STEEL ETCHANT OR NICKEL AND COBALT SUPERALLOYS ETCHANT S1098
No specific	TITANIUM ALLOY ETCHANT S1093
No specific	cotton swab

3. Job Set-up
Subtask 70-27-00-860-053-A

A. General
(1) This task provides the instructions on how to do the swab etching cleaning.
(2) Chemical etching is used for preparation of metal surfaces and comes before the application of fluorescent-penetrant inspection. The etchants remove smeared metal from grinding, and light oxides generated by heat treatments, welding operations or service, which are likely to clog or prevent surface indication of defects such as cracks or microfractures.
(3) Etchants must be applied with care, especially when a part is made up of different metals or alloys requiring different etchants for the different metals.
(4) The procedure for applying local etchants is standard for all metals, but the etchant used is based upon the metal to be etched. The etchants are classified into four groups of metal as follows:

CLASS	MATERIALS (SOLUTION NO)	METAL TO BE ETCHED	SHELF LIFE OF STOCK SOLUTION
A.	TITANIUM ALLOY ETCHANT S1093	ALL TITANIUM ALLOYS	1 MONTH
B.	STAINLESS STEEL ETCHANT OR NICKEL AND COBALT SUPERALLOYS ETCHANT S1098	ALL LOW CHROMIUM ALLOYS NICKEL AND COBALT ALLOYS HIGH CHROMIUM ALLOYS	6 MONTHS
C.	DELETED
D.	CARBON STEEL ETCHANT S1095	CARBON AND LOW ALLOYS STEELS	6 MONTHS
E.	ALUMINUM ALLOYS ETCHANT S1096	ALL ALUMINIUM ALLOYS	1 YEAR
F.	DELETED
NOTE: Class C and F are cancelled. Class C and F are superseded by Class B.

Subtask 70-27-00-941-053-A

B. Equipment
(1) Protective equipment and safety installations such as eye cleaning facilities, emergency showers, gloves, goggles, protective clothes and facilities for neutralization of acid and alkaline splashing.
(2) Facilities for discarding of used solutions.
(3) Efficient system for ventilating gasses and vapors.
(4) Trays or containers for disposal of solution-soaked swabs and rags after use.
(5) High-density polyethylene or polypropylene containers carrying a label showing the nature of each etchant.
(6) Supply of distilled or deionized water for rinsing of titanium.
(7) Cotton swabs and tweezers.
(8) High-density polyethylene or polypropylene beaker and saucers for sampling and instant use of small quantities of solution.

4. Procedure
Subtask 70-27-00-110-071-A

A. Swab Etching
(1) Make sure that all surfaces to be etched do not have any oil, grease, scale, or other extraneous material.
(2) Make sure that the etchant solution is at room temperature.
(3) Pour a small quantity of stock solution into a clean BOTTLE - SAMPLE, STERILE. This quantity will be the working solution and is not to be returned to the stock bottle.
(4) Soak a cotton swab with the working solution and swab the surface to be etched (see the table at the end of the subtask for etching times). Keep the etching solution in the defined boundaries of the area to be etched. Masking may be necessary to do this.
(a) Keep fresh solution in contact with the metal surface at all times by dipping the swab into the working solution periodically.
(b) Rub the swab continuously over the surface of the metal being etched, to prevent the formation of an inert sludge.
(5) After etching, blot up etching solution from the metal surface with a clean PAPER - TISSUE or LINT-FREE COTTON CLOTH (Material No.CPNCL02069) .
(6) Gently wipe the etched area at least three times with a LINT-FREE COTTON CLOTH (Material No.CPNCL02069) or PAPER - TISSUE saturated with clean water. Blot dry with clean cloth or paper towel. Optional rinse procedure is to use flowing water and dry air.

NOTE: Deionized or distilled water must be used to rinse titanium.

(7) Discard used working solution, rinse and dry plastic container for future use.
Table of Guideline for Etching Time

MATERIAL	TIME	CLASS A	CLASS B	CLASS D	CLASS E
All titanium alloys	60 s - 90 s	X
Carbon and low steels	60 s - 90 s			X
All aluminium alloys	60 s - 90 s				X
Maraging steels ( Maraging 250, etc.)	60 s - 90 s		X
Low expansion alloys (Incoloy 903, 909, etc.)	2.5 min - 3 min		X
All stainless steels (PH, etc.)	4 min - 5 min		X
Iron superalloys (A286, etc.)	4 min - 5 min		X
Turbine airfoil nickel superalloys (Rene 77, 95, 125, etc.)	60 s - 90 s		X
Non turbine airfoil nickel superalloys (Inconel 600, 625, 718, Udimet 500, 700, etc.)	4 min - 5 min		X
Cobalt superalloys	4 min - 5 min		X
NOTE: When etching surfaces containing two different alloys with different etching time specified in the table above, use the shortest etching time specified.
NOTE: A clean and active surface (a surface containing no oxides and no scales) is required for effective etching of a cobalt and nickel superalloys. Light abrasion is recommended to activate the surface prior to etching.

Subtask 70-27-00-210-050-A

B. Quality Assurance
(1) Do a visual inspection immediately after drying.
(a) Visually check that local swab etching has macro etched the surface.

[Rev.10 from 2021] 2026.04.01 02:20:56 UTC