If you are looking to actively weather your project, then we have developed an accelerator agent called XL-08.
XL-08 can be applied to bare Corten steel, or any metal you intend to rust, using a brush to ensure the solution gets in to the surface of the metal.  Once applied, ensure you monitor the effects of the accelerator until you reach the desired effect.  you may wish to add water to ensure the surface does not dry up.  You can also add more XL-08 if needed.
Once the surface has been weathered to the desired effect, rinse off the XL-08 with fresh, clean water and allow the metal to air dry.  If you are short on time, then you can flash dry the surface with isopropyl alcohol.
Before applying our coatings, ensure the surface has been neutralised.  We recommend using our Prep505 cleaning and preparation fluid for this.