I'm blown away, after wire-brushing and grinding of the welds, as to how the Ospho destroyed what little rust was left .
Caution: Don't get it on the concrete floors or painted areas!

Here's a close up of the treated metal before using the Metal Etching Primer.
Clean the area first then spray on the Ospho and wait maybe 20 min, then wash off with a very damp towel/rag and voila! I've read that Ospho is an Excellent primer too!