Priming and painting hot rolled steel?

[tube_guy]

When priming and painting hot rolled steel, should the mill scale be removed down to bare metal or would it be better to apply the primer over the mill scale? The primer used is Sherman Williams 988 etching primer. Thank you for any help you can provide.

[fun4now]

if its a cosmetic pice i would take it down to bare metal for shore. if its nothing special, you could probly get away with leaving it on.
i generaly take mine to bare metal unless its just some thing unimportant you will never see like a shelf bracket or hinge type thing inside the shop.
for this tool holder i left the scale on, but its inside and will be getting a beating on a regular basses, so cosmetics is not important.

[tube_guy]

Thank you for the reply and the pictures. I'm just about finishing up a cart for my welder and I used some hot rolled sheet for the shelves. The mill scale is pretty difficult to sand off and it seemed to really protect the steel from rust. I was just wondering if the primer and paint would do as well at protecting the steel from rust as the mill scale. I do want the cart to look nice, so I'll take it down to bare metal. Thank you again for the help.

[fun4now]

you could just sand it down till you have a nice smooth serface, then prime and paint from there. i'm shore it would look just as nice in much less time. if its a shelf you will be repainting befor too long any way. i wouldnt worry too much about a clean steel first. a good primer and some 400grit sand papper and you should have a verry smooth finish to paint. and it will look great.

[Bert]

Friend of mine that built custom boat trailers for over 35 years said the mill scale will rust through much faster, causing the rest of the trailer to rust faster. He always used a 41/2 grinder to take off the mill scale, brushed on zrc then enamel paint.

[fun4now]

brushed on zrc ????? whats that???

[Bert]

Zinc Chromate. Good primer. oil base. buy it at gaspro or some good hardware store. I fotget if Home depot sells it. I don't think so. Used a throw away 2 inch bristle brush to apply. Note: on those cheap brushes, whack it for a couple of minutes to get those loose bristles out so they don't come out on your paint.