Acetone - risk or benefit?

[WNYBill]

Acetone and Alphabet org, 50-50 is the best penetrating oil. And much cheaper than PB Blaster! I use it on rifle bores too.

 

[rodm1]

Acetone is used a lot to clean before welding.

 

[Firewalker]

I use acetone based paint thinner to clean steel and aluminum before welding but not acetone alone, it flashes off to fast leaving condensate on the surface.