Posted by gmharris [71.105.34.147] on Thursday, January 01, 2015 at 18:02:22 :
In Reply to: Re: Can't see any Rust? posted by Willy-N [72.171.192.62] on Thursday, January 01, 2015 at 14:37:27 :
How long flash rust takes to form depends on humidity. Here, in the desert, I can leave bare metal for months and it won't flash. In other places, flash rust will begin to form almost immediately.
People think Winter is one of the worst times for humidity and flash rust. Actually, Winter is a great time. As the temperature drops, the absolute humidity, the amount of water that the atmosphere can hold, drops. So, there is less water vapor to form rust.
So, metal kept in a cold, ventilated shop (absent other humidity sources) is less likely to rust. Where you have problems is bringing cold metal into a warm environment.
Get something on that bare metal before it does rust. Done correctly you only have to use phosphoric acid on those little spots you can't get a sander into. Then, only daub those spots with a rag dampened with phosphoric acid. That way, you won't have excess acid on the metal.
We're not talking about invisible rust. Phosporic acid is not going to form a protective primer with "invisible" rust. It needs something to react with.
That "pickle" stuff is something else. It may also have phosphoric acid or something similar, but it has other chemicals for long-term rust protection.
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