Hi
I'm not a fan of the cold blue stuff - yes, it does the job....just, but leaves a bad smell & as you know it wears off quickly
I found a new product a couple of years back on a well known internet auction site in the USA.
Look for WARM BLUE - it's a pack with 3 chemicals: a cleaner, a bluing agent and a fixer.
Works really well - you can touch up worn spots without any bother...and if you look at the area you have done in different light & are not happy, you can go back & add more of the bluing on top.
When done it was VERY difficult to spot where we had been adding the blue solution & no bad smells, etc.
Not sure who made it - but it was about $35 or $40 for the kit.
If you cannot find it get back to me & I'll e-mail my mate for the name, etc.