A power washer with a psi of 3500 or more shoud take most of the loose stuff off. From there, good old fasion elbow grease is, to my knowlege, where you go from there.
There are strippers that can be used if you care for the expence. Even in that route, your going to be using a washer.
If you've never used a washer before, be warned, they can be dangerous mashines. Be very careful using one.
Hope that helps
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