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Hi Scott, Don't expect too much from 5717S. It is a phosphoric acid based metal cleaner/conditioner that works well for light surface rust ONLY. It really is not a rust "treatment" and is supposed to be followed by a conversion coating step with 5718S, if you follow DuPont's specific instructions. Unfortunately, this fact is usually not spelled out on the 5717S label. It is, however, in the 5717S technical data sheet. The product can be used alone but use with the companion product, 5718S is preferable. Both products together can easily handle micoscopic and light rust and are used to "etch" the metal prior to priming. They both are rather messy to use. You are unlikely to be left with any shiny metal though. After rinsing following 5717S, you will probably notice a streaked, "rusty looking" non-uniform patchwork, for lack of a better description. That should change to a whitish or greyish, looking patchwork after the 5718S is applied and a second rinse is used as stated. It may even be somewhat dusty in the whitish areas and you should wipe it down after drying and prior to priming. Priming should be done soon afterwards. IMO there really is no good substitute for sandblasting if any significant rust is present. The next best thing is sanding or wire brushing of "relatively loose" rust and the use of a rust "treatment" for any remaining, tightly adherent rust. I have used "Extend" rust treatment by Permatex (available at NAPA stores) for places that had tightly adherent rust and that were inappropriate for sandblasting ( a tender gas tank :o) for instance). It is a product that basically encapsulates any rust from moisture and oxygen with a hard, black coating and can be topcoated with paint. I have had good success with this product over the last two years, at least.  Rod
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