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Stopping copper selenium blackening (gunbluing) from oxidizing

We are fabricating a large steel staircase (three floors) out of C channel that has been taken to a 220 finish. There are wood treads, so contact is made with the staircase only on small parts of the landings. The customer wants the gun blue look. In our sample pieces we have tried blackening with copper selenium. We have also used a stained glass patina that patinas the lead after soldering. After the application, we have tried neutralizing with water, methyl hydrate, and baking soda / water mix but it is difficult to say when we will get rust and when we won't. We have then tried lacquer, wax and rust inhibiting oils as a finish. We had the best success with a gun oil, but are not sure how often the oils need to be re applied. Also, the staircase is installed but not finished and is starting to rust. The rust is fairly easy to remove (except for some tricky places). We need to make sure whatever we apply as a finish will not rust later down the road. Also, the customer wants a low maintenance finish.
I am wondering if anyone has experience blackening such a large piece, and how they stop rusting (how to neutralize), and what is the best finish to use after neutralizing. What would be the best wax? Is there a low maintenance wax? And, what is the best way to gun blue large areas to maintain a consistent look without oxidization...

John Ross
fabrications - Vancouver, BC Canada
2006

Better try to use special colours by Alsa, you can blue your staircase but bluing is not corrosion protective finish. Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
2006