prepping metal

[GirlScout1]

I am in the process of fabbing some bumpers. The steel I got has a coating on it to keep it from rusting. What is the best method to getting all of this off? Just use a grinder or flap wheel?

-b

 

[Lawn Cher']

What kind of coating? Just some oil or is the stuff galvanized?

 

[Captain Ron]

...
or is the stuff galvanized?

Hot rolled scale.

--ron

 

[Lawn Cher']

Hot rolled scale.

--ron

Is that like a gator finish?

 

[GirlScout1]

basically just like an oil coating yet sticky. guess I would classify it as grease.

 

[Abugarcia]

Get a good wax and grease remover. If you try to grind it off you will work it into the metal and make life more difficult in the long run.

 

[5-90]

Any organic solvent should work - I've used Acetone, MEK, and Naptha in the past. Use Scotch-Brite on tough patches.

Part of that is scale from HRS, and the "greasy" part is from some variation of Cosmoline. If the Acetone, MEK, or Naptha doesn't work, leave it out in the sunlight and spray EZ-Off Oven Cleaner on it - works like a charm! (A little trick I learned from ordnancemen...)

5-90

 

[GirlScout1]

...leave it out in the sunlight and spray EZ-Off Oven Cleaner on it - works like a charm! (A little trick I learned from ordnancemen...)

5-90

SOunds like a great idea..oh, wait I live in WA. WTF is sunlight?

 

[bj-666]

just as a side note onec ya get the greasy stuff of you still want to hit it with a sander to get thru the scale then your good for paint.

 

[dan89XJ]

I think I would make the bumper first. The cutting and welding would burn some of the stuff off, and then leave another kind of mess. So.. might as well just build it first, then clean it up.

 

[katarn444]

I think I would make the bumper first. The cutting and welding would burn some of the stuff off, and then leave another kind of mess. So.. might as well just build it first, then clean it up.

Bad idea, all of that crap is going to burn and contaminate your welds and your lungs. It is best to weld on clean metal. If the stuff is thick enough you might even have problems stricking and arc.

K

 

[Abugarcia]

I agree that you should clean the mil scale off of the metal before you weld. Although your not going to have a problem striking an arc, the puddle will act differntly and your weld will be contaminaded. Its not more toxic to weld without removing the mil scale. Mil scale is simply impurities that rise to the surface of the steel when its heated and rolled into sheets.