Sorry, meant to add to neutralise an acid such as Oxalic, dilute the comncentrated solution you've used to treat the frame, then add as much water as you possibly can to make it as dilute as possible.
Then add "Soda Ash" (Sodium Carbonate or Soda Crystals) to the bath. Best to dilute these in water first too.
Basically, always use as much of the dilute chemicals to each other, as slowly as possible. Acid + Alkali = mucho heat if they are concentrated