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Letter 4069
How to clean hot rolled steel for
preparation of a rust finish?
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What can be used to clean hot rolled sheet steel to remove the
factory coating? The reason I ask is because I make lamp shades and
finish them with a rust finish. Someone had suggested I use muriatic
acid? Is there a less toxic chemical available to clean this rolled
sheet metal with?
Philip Burch
custom furniture - Phoenix, Arizona
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Dear Philip
You don't obligate to use Muriatic Acid , as a matter of fact
every acid will do the job including Citric Acid . You have to remove
the natural oxide layer which existing on the metal surface and then
you will get rusted again.
TIP - You can increase the rate of rusting by using Salt Spray
cabinet . Just put the part in it and you will get every level of
rust you want
Yehuda Blau
- Haifa, Israel
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I assume that you need to remove the scale from the steel.
Inhibited phosphoric acid at 50-70 deg C preferably containing
degreasing additives (commercial products readily available)will do
the job in a stainless steel tank. Water wash and use a final hot
rinse containing rust inhibitor. If you require higher paint
performance you may need to consider further pretreatment stages.
Roger Bridger
- Croydon, Surrey, UK
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To remove any deposits of white rust I suggest an ambient
temperature immersion in inhibited phosphoric acid with HF based
activator. Immersion time 5 - 10 minutes then rinse in cold water and
dry.
Alex Jennings
- Hawarden, North Wales
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