Removing Metallic Layers from Spirals (Helices) for Reuse
Most applied deposits can be readily removed to enable reuse of a plated spirals (helix) by immersing it in a 50% by volume concentrated nitric acid solution at room temperature, then water rinsing and drying for weighing and subjecting it to another plating stress test.
Stripping the deposit from a spiral (helix) takes 15 minutes to 2 hours at room temperature depending on the thickness of the coating. Make sure all the deposit is removed, then rinse and dry, then visually inspect the spiral (helix).
Silver metal deposits can be stripped with anodic current in a solution of 8 oz/gal caustic soda and 16 oz/gal sodium cyanide.
Gold deposits can be stripped by immersion in a solution of 16 oz/gal sodium cyanide and 3.2 fluid oz/gal hydrogen peroxide.
Copper deposits can be removed by immersion at room temperature in a solution of 32 oz/gal chromic acid and 2 fluid oz/gal sulfuric acid.
For most metal deposits in which the electro deposition chemistries do not attack stainless steel, the deposits can be stripped with anodic treatment in the plating solution that was used for the internal deposit stress evaluation.
When the exterior surface of a helix shows visible etching, the helix should be discarded.