corey
It has to be clean & oil free to blue. I usually scrub parts to be blued in warm soapy water, then rinse well and throw then in a pot of water & boil them for a few minutes. Don't pick the part up from the pot! If there's an oil scum on top of the water you'll get it on the part again. Instead, slowly pour the water out of the pot so the oil goes with the water. Then the part will be clean & warm and should take the bluing.