Wheeler Engineering Gun Blue?

[Plink]

Has anyone used this? Did you have problems getting it to darken? I'm trying to cold blue an old Savage model 24. I've only been patch testing it so far, but I can't get it to darken on the barrel hinge or the hinge pin either, even after multiple applications.

These pieces may have been color case hardened originally, but between the rust that was on the gun, and my sanding and polishing, I'm way past any case hardening. I've never had problems cold bluing case hardened parts once I got past the case coloring. Could these parts be made of iron perhaps?

I've written to Wheeler and they suggested going to a 400 grit finish. I was using 600. I'll try that. Anyone have any other ideas? Thanks in advance.

 

[dfariswheel]

Around hinges and pins, the probable problem is lube oozing out of the joint and contaminating the area.

It's extremely difficult to remove lubes from these areas, and more lube creeps out and spreads over the area. The amount of lube is so small that it's impossible to see it, but that's enough to prevent cold blue from working.

My only suggestion is to use more aggressive cleaners, and warm the metal up between applications to help evaporate any lube.
Heat WARM, NOT HOT. Use a hair dryer to prevent overheating.

For solvents, I suggest an aggressive cleaner like Simply Green, followed by multiple applications of Acetone.

Use a synthetic Scotchbrite pad with the cleaner to liberally scrub the area, then switch to Acetone and a clean toothbrush.
After scrubbing with Acetone, force dry and heat with the hairdryer, then use more Acetone.
After the final cleaning, warm the metal warm with the hairdryer, then apply the cold blue with a large cotton swab.
If the blue beads up and rolls off the area, it's still contaminated with something.
Try applying the blue with a piece of 0000 steel wool.

Take a piece of steel wool and soak it with alcohol to remove the oil it's treated with to prevent rust.
Shake it off, then dry with the hairdryer.
Then use the steel wool to rub on the cold blue.

If you're using 600 grit, using a different grit will do no good, since as I said, the problem is probably contamination.
Hinges and hinge pins are not made of iron, and iron blues very nicely anyway.

 

[Plink]

It was cleaned with Simple Green and degreased in Brownells Dicroclean 909. I don't have acetone handy, but I do have TCE, which is a very good degreaser. I'll try scrubbing it more and using the TCE to see if it helps.

I've blued a lot of guns using a number of different cold, hot caustic, hot water, and rust blues, but I've never ran into this problem before.