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REVISION CARDS - OIL BLACKING AND CHEMICAL BLACKING OF STEEL
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TRADITIONAL OIL BLACKING OF STEEL

With steel, corrosion to the surface will always be a problem, especially if the product / component is in contact with moisture, as carried in the atmosphere. One of the most cost effective ways of preventing tarnishing / corrosion to the surface of steel, is to ‘Oil Black’. This can be achieved on a small scale in schools, although strict safety precautions must be taken.

1. Clean and degrease the steel. 2. Heat to ‘red’ heat on a brazing hearth. 3. Use tongs to drop the steel into a container of old engine oil. 4. Allow to cool and remove the steel (now with a blacked finish).

 

BLACKING OF STEEL WITH A
CHEMICAL BLACKING SOLUTION


This is a process called ‘Cold Chemical Blacking and does not require the steel to be heated on a brazing hearth.


1. Clean and degrease the surface of the steel being ‘blacked’. 2. Use tongs to drop the steel into a solution of ‘Chemical Blacking’. Leave for no more than five minutes. 3. Remove from the blacking solution, wash with water, dry and drop in a ‘Dewatering’ solution. Leave for ten minutes. 4. Remove and wash in clean water, revealing a ‘blacked’ finish.

 
 
 
OIL BLACKED AND CHEMICALLY BLACKED COMPONENTS



 

 
 
 
QUESTIONS
 
1. Why is the ‘blacking’ of steel components sometimes needed? 3 marks
 
 
 
 
 
 
 
2. Describe the process of oil blacking OR chemical blacking of steel? 4 marks
 
 
 
 
 
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