You are so right fire scale is a pain, in you know where,
I had some that would not even sand off.
But the easyest way to take off scale ,and the fastest
it
Muriatic Acid the type for swiming pools.
1/2 cup acid 1 gal warm water, and about a 2min bath.
(you mite want to brush it a little.)
then rinse with water, add baking soda to rinse water,
and your done.
now acid has its bad side so TAKE CARE handle it properly.
Now the scale is gone the metal will look gary in color
At this point it is so clean that your finger print
will rust.
The pores of the metal are open ,this is a good time
paint or prime.
DON'T LET IS SET AROUND ,IT WILL RUST!
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