Removing mill scale

[Vietti]

Does anyone know of a good way to remove the mill scale from hot roll sheet/stock.?? Tried a flap disc and it works but tends to remove good metal and the disc wears quickly. Thanks, John

 

[Jasonb]

1/2hour in brick cleaning acid which is hydrochloric acid, the scale will flake off and leave a matt grey surface. rinse, dry and apply WD40 as the surfac ewill quickly rust if you don't

 

[Vietti]

Thanks, I have some acid and will try it.

 

[Vietti]

Worked like a charm, thanks.

 

[OrangeAlpine]

a coarse wire wheel works good.

 

[awake]

I think some people may use a weaker acid, e.g., vinegar - takes longer but equal results. Emphasis on "I think" - this is my impression from some YouTube videos, and I don't know that I have actually heard the details. Perhaps someone can verify or refute?

 

[ddmckee54]

I think we've probably been watching some of the same videos, but they both work. The HCL works faster usually within hours, while the vinegar will take at least overnight, maybe days to work. The vinegar will leave the scale as a grayish-black film that will need some scotch-brite and elbow grease to remove. With either the hydrochloric acid or the vinegar, rinse the part, dry, and apply either oil or WD40 to prevent rust.

 

[peterl95124]

I prefer Naval Jelly rust remover (although its not as effective on black iron oxide as on red iron oxide so you might want to start with hydrochloric/muriatic), it leaves a grayish iron phosphate surface finish which is fairly rust preventative and a good paint primer, BUT, if you want a smooth shiny surface don't bother with HR, my experience has been that you'll end up with wavey marks left over from rolling that take for ever to sand out and just not worth the effort.