I have a commission to paint an image on a large saw blade. As I've only used charcoal and pastel on paper and oils and acrylic on canvas, I don't know how to prepare the metal surface. Also, what would be better to survive the metal contractions and expansions due to heat, oil or acrylic? Would welcome all input.

Poat this good question in the Discussion Forums at www.amien.org and we will gladly answer it.

Mark Gottsegen

I should have said "post..."

You know, I had the very same question this past summer when I was asked to paint a large saw blade! Well,what I discovered was: 1). The metal MUST be clean. 2). When metal is clean and dry, get a can of Krylon (or your choice) metal primer spray paint. That's right. Spray paint primer. I used the rusty color.Oil or acrylic will work. I used oil as I prefer oil.
After the paint was allowed to dry thoroughly, I sprayed a fixitive to prevent spoilage.The saw blade was to be kept inside so, weather was no problem.
Since then, I discovered other painters had done the ve4y same thing.
So, go for it and good luck!

It's a good idea to abrade the metal surface before priming it: an electric orbital sander will work, with a wet-dry sand paper. Wipe with a rag dampened in denatured alcohol and let dry.

The spray primers from automotive supply houses are usually colored gray. If you're painting in oils, which get transparent as they age, then the gray primer will affect all the colors and their relationships. These primers are also designed for automotive applications, and so are not expected to last more than, say, ten years. Then what?

Maybe a better idea: sand and degrease as above, and then apply a primer of a white absorbent acrylic dispersion ground (aka "gesso" although they are not true gessoes).