Weathering Corrugated Metal Sheet - Model Railroader Magazine

Do not forget the 'nail heads'.

I use a blunt pin or a pounce wheel with a straight edge to make the 'nail heads'/dimples. I make the dimples on the backside (walls) or underside (roofs) in the valleys of the metal sheeting before weathing.

When viewed from the outside, these dimples will look like 'nail heads' on the ridges. You can make rust streaks flowing down from these dimples. Look at photos or go measure a building and you will get the spacing of the 'nails'.

It depends on my mood what weathering technique I use.

I have used the Radio Shack PCB etchant (FERRIC CHLORIDE). I have one 16oz. bottle left yet.

From the Big Box Hobby store, The MODERN MASTERS metal effects rust is a three part process, brush on 'primer', brush on 'iron' and last, the spray on 'rust activator'. $21.99. pricey. 

I have used no less then 5 different manufactures of powders, plus chalks, oil paints and natural rust. In my old days I scraped artist chalks and pastels. I do not remember buying ready made powders in a container until the last maybe three years. But now everybody has something in a powder/pigment.

I have used an Air brush and hand dry brushed with bottle paint.