BLACK COLORING AGENT
- ALBLAC # 619
Description
This is to color steel and low alloy, and you can have beautifuly colored metal simply by dipping. The following chemical can be used for this method.
ALBLAC # 619 lump, flake or powder.
This method meets with the following specification.
U.S. Army Specification
MIL - C - 13924 A (1956) CLASS2
MIL - P - 12011 (1952) FINISH NO. WW 04
GRADE 2 AND - 10398
APPLICATION
The surface to be treated must be clean.
Sand or shot blasted surface will be rough and acid wash primed surface will be dull black. The surface must fully polished after sand blasting or acid wash. Cold treated surface (pressed or pulled) may affect the color to be lighter. Good coloring depends on surface preparation.
Coloring Black by Oxidization. (Fe3O4)
1. Preparation of treating tank
Fill a half of the tank with water and add ALBLAC#619 to the water slowly. Start heating the tank when added ALBLAC is over half the required quantity, and keep adding small quantity of #619 and water. When ALBLAC#619 is dissolved fully and temperature goes up to boil at 141+2oC, you can start coloring by dipping. When the boiling temperature is higher than 141oC, adjust the temperature by adding some
water and when the boiling temperature is lower than 141+2oC, adjust it by adding more colorant or vaporizing water.
Treating Tank: ALBLAC#619 1000g
WATER 700g
The temperature of processed liquid will be 137oC. Dip the objective after heating it in a mild alkaline liquid (1-2 minutes). It will take about 20 minutes to finish coloring but it may take 30 minutes in some cases. Coloring time depends on the kinds of material, and grades of surface preparation, It is good to keep the tank temperature between 137oC and 145oC. If the temperature is over 150oC, redish brown sediment may stick to the objective or rate of oxidization can be reduced rapidly. After dipping, take the objective from the tank, wash with hot water and remove alkali by rinsing with clean water. (0 minute washing is proper and long time washing may corrode the objective of high carbon steel), And then wash the objective with mild chromium acid and dry it.
2. Mild chromium acid wash
This is to neutralize the little alkali left on the objective and to improve the anti-corrosion of the film.
Composition of chromium acid : anhydrous chromium acid 2.5g
water 1,000ml
To keep the concentrated degree at PH2-3, add proper quantity of anhydrous chromium acid. Treating temperature is to be between 65oC and 88oC, and dipping time is 30 to 40 seconds. After this treatment, dry the objective with compressed air, hot air or drying oven. Drying time should be within 5 minutes.
3. Finishing Treatment
To keep the film from corrosion and aesthetic purpose, you may use rust preventive oil, varnish or a clear lacquer.
4. Procedure
Degrease - wash with water - wash with acid - wash with (Sand or shot blasted)
water - coloring - wash with water - wash with chromium
acid - oiling or coating