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Metal finishing Q&As since 1989
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Chemical cleaning a dark deposit from surface of aluminium engine block casting
We have a number of engine blocks that need to be cleaned to remove a dark grey deposit from the cast surface.
We have tried 20% Nitric acid, 10% phosphoric acid, petroleum spirit, and toluol with limited success. The deposit could be a burnt on die lubricant as it feels a little greasy.
I need to organise the treatment of over 100 engine blocks to remove this stain but am at a loss as to what will work without attacking the cast iron cylinder sleeves.
Can you help
Automotive - Melbourne Victoria Australia
2005
Hello Mr Graham;
Use your nitric acid cocktail after swaying your blocks around in a solution of 50 - 100 gms per litre of Sodium Hydroxide for 20-60 seconds first and rinsing afterwards. This won't affect your steel Liners but will effectively etch the aluminium first.
![Khozem Vahaanwala](../portraits/khozem_vahaanwala2.jpg)
Khozem Vahaanwala
Saify Ind
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Bengaluru, Karnataka, India
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2005
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