Rusty Pipes

As far as your problem, there are several things you can do. I would start by painting all of the pipes a dark gray, so that they would resemble real pipes. I would say if using rustolium, then smoke gray would work well for this. To add the "rust" I agree with cdolsen. Sponge application is a very good idea. I would go with a dark redish brown coating. Make it heavier in some spots, and mkae it random where you concentrate the color. Then go over that with a orangey-brown color that is lighter than the red-brown. Sponge it over the red-brown in the same random manner.
After this is all done, stand back and look at your pipes. If they dont look rusty enough, repeat the process.

Another thing you could do, with the same paints, is:
After you paint the pipes gray, dip a large paintbrush in the red-brown paint. Then run the brush harsely and quickly over a piece of screen. This will create a spattered/speckled texture. Do this several times. Then when dry, go over it with the orange-brown using the ponge method.

Important - Do not use the Spray variety of paint directly. If you spray the pipes directly, you will get runs in the paint if you do not do it perfectly. If you have to use spray paint, then do it from a distance, so that the pipes only recieve a fine mist, or dusting of paint. If the paint gets thick enough to collect together and form drops or pools, then it will run, and ruin the effect.

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"May the Force be with you."

or mix them into a paint and spacle it onto the pipes play around with scrap to see how it works, also try different "flake materials" to see what works best

later
Tom

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What everyone seems to forget is that once we look past race, religion, gender, and all that, everyone on this planet is first and foremost...

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