Blueing small rust spot repairs: Stubborn spots will not blue.

[42ndDR]

I am trying to repair a couple of small rust spots on the receiver of a Marlin 1894 44 Mag rifle circa 1979. The lever and barrel end reacted perfectly with the Birchwood Perma Blue however the spots on the receiver refused to react and covert to blue. I used alcohol to clean, fine steel wool, Birchwood rust and blue remover, and then the Perma Blue 4 times and it still looks like bare metal. I am thinking to try the Super Blue next but want to understand why it is so resistant to blueing.

Any ideas what it is happening and any other suggestions on how to treat the spots?

TIA

 

[Trapper]

I’ve had mixed results with cold blue. I use Brownells Oxphoblue, normally polish the area with XF bronze wool, clean the area with a cleaner / degreaser, warm the steel with a heat gun or hair dryer, then apply blueing with a q tip, allow it to dry for a couple minutes, then clean with a patch soaked with a little water. Apply more cold blue and repeat the process as needed. Once the desired color is achieved, clean and oil the area.