Your method for degreasing?

[Olle]

Originally Posted by lugerholsterrepair

Boiling water?

I used to work in the lab at a refinery many years ago, and hot water was actually the best way to clean the thick, gooey pitch oil out of bottles and test tubes. I use it sometimes when I have to deal with more massive amounts of gunk, just like Ed says it will soften the hardened deposits and make them easier to scrub off. Solvents (for example acetone) seem to have the opposite effect sometimes, it can dry out old goo and turn it into a hard crust that sticks even worse.

I had a discussion with a guy who works with metal plating (which requires a 101% clean surface) and he used steaming hot water with a squirt of cheap dish detergent for the final cleaning. Then he rinsed in hot tap water immediately to get the residue off. The parts were so clean that he had to carry them in a pail of water to keep them from flash rusting during the short trip from the sink to the pickle bath. He had to wear mittens inside rubber gloves, but he said that it works great. I'm sure it does, but it's probably overkill for bluing purposes.

In this case it seems to be a matter of just a very thin film of something, so a good degreaser and a rinse in hot water should suffice. Now when I think about it, another cause of the problem could be the fire. Hardened steel is usually more difficult to blue than softer steel, and it's quite possible that the fire made the hardness uneven enough to show in the bluing.