"Mirror" finish for mild hot rolled steel

[Alann]

I'm a newcomer to welding - just started 9 mos ago.

In trying to do some sculpture work with mild steel (1/8 ") plate I've been able to develop some brightness by using my 41/2" grinder and working up to 120 grit sanding disks. However, this leaves swirls which I'd like to get rid of. I can't find any finer disks after a search of the internet and some interesting phone calls with some very knowledgable suppliers. I tried using a belt sander which helped, but I ended up with vertical marks instead of circular ones.

I'd apprecaite any help that's available. Many thanks in advance for your help.

Alann

[riley mcmillan]

I always had pretty good luck with an orbital sander with the wet or dry sandpaper and use oil with it. Keeps the paper from gumming up. Then after sanding with increasingly finer sandpaper, get yourself a fabric disc and rouge stick and work it over with that. Just be sure and wear eye, ear, and lung protection.

[prop-doctor]

mirror finish on mild steel? mild steel won t shine like stainless steel
a mirror finish on stainless is done by finish grit sanding, then buffing with rouge and a cotton buff wheel
on my props i use a large grinder/buffer i use a cotton buffing wheel with a sanding compound (PB-80) then switch to different buff wheel and use a green rouge then a white rouge
mild steel will rust quickly

[76GMC1500]

Mild steel will shine like stainless, it just corrodes if it ever gets humid. You should also start with cold rolled steel and you can skip the 4 1/2 inch grinder step and go straight for the wet dry.

[DDA52]

A Norton Bear-Tex wheel will leave a bright finish without too much in the way of marks. They are like a Scotchbrite wheel for grinders....not exaclty, but close.

[zapster]

if your doing plate and you need a mirror finish?
find a good machine shop with a "blanchard" grinder...

oh man!

you want mirror? you get mirror..

...zap!

[Alann]

Thank all of you for your advice. I've got a lot of things to try. I'll get back to you after I've had a chance to work on your suggestions. As I've read about it elsewhere, I was thinking of applying some kind of clear exterior finish if I succeed in getting some type of satisfactory high shine (mirror-like?) finish. What do you think? Thanks again, you guys, for your great suggestions.
Alann

[76GMC1500]

Once you sand with a 320 grit, you can get the mirror finish you want by finishing with a metal polish. White rouge and a muslin wheel work best for this. Simichrome works well and can be done by hand. Rouge is way cheap if you are going to be doing a lot of polishing.

[Rojodiablo]

Originally Posted by Alann

Thank all of you for your advice. I've got a lot of things to try. I'll get back to you after I've had a chance to work on your suggestions. As I've read about it elsewhere, I was thinking of applying some kind of clear exterior finish if I succeed in getting some type of satisfactory high shine (mirror-like?) finish. What do you think? Thanks again, you guys, for your great suggestions.
Alann

Epoxy gloss clear will do the job. Talk to body shops who do top-shelf jobs. They will know what material to use for your area. Don't be scared by the $250 a gallon price for the top coat. Be terrified!!!

[Bob Warner]

As someone that does mirror finished regularly I can tell you how I do it. I have the benefit of a belt grinder so I can do it quickly but the same method can be done by hand or with hand tools.

First get it clean from scale and such with your angle grinder. Anything that is flat needs to really be FLAT or it will be obvious. Hopefully flat is not a requirement.

Use whatever sanding machine you have to get to about the 400-800 grit stage.

Hand sand up to 2000 grit and then polish with Flitz or a rouge on a worn out piece of sand paper.

On my belt grinder I polish to 400 grit then go to a cork belt with rouge on it and mirror within minutes. Most people don't have the grinder I do so you have to do a LOT of hand work.

If you are using machines, slow them down if you can as the grit gets finer.

When you are all done, if your piece is small, use tru-oil on it to preserve it. If it is big, clear krylon works well.

You can get a mirror finish on anything pretty much. Stainless clouds up but you can get through it. Mild steel is pretty easy.

Here is a polished railroad spike, all done by hand (before I had my grinder).