So, I've been playing with some hot caustic bluing, the basic formula is 5lb of sodium hydroxide and 2lb of sodium nitrate per gallon of water. Bath is operating at 290 degreed F.
After bluing is done i used to just leave parts in oil overnight to let them soak up the oil. Recently i tried and very much like a new method. The new oiling method consists of placing parts in the oil container and the oil container into a vacuum chamber. Then i pump the air out down to about 5000 micron and let the oil outgas. This pulls moisture as well as air out of black oxide finish. So far i only experimented with used vacuum pump oil not a true water displacing oil or oil with corrosion inhibitors added to it. My worry with "proper" black oxide oils is that they may be a mixture of oils and solvents, which would separate under vacuum. I see the black oxide oils advertised as "dry to touch" which tells me that they have solvents in them, which evaporate at STP. Can anyone recommend a "proper" black oxide oil which can survive vacuum? My worry with continuing using use vacuum pump oil is that the vacuum pump oil is hydrophilic, so it will absorb moisture from the atmosphere and bring it into black oxide finish, ultimately doing the opposite to what it is intended purpose is in the oxide finish.
After bluing is done i used to just leave parts in oil overnight to let them soak up the oil. Recently i tried and very much like a new method. The new oiling method consists of placing parts in the oil container and the oil container into a vacuum chamber. Then i pump the air out down to about 5000 micron and let the oil outgas. This pulls moisture as well as air out of black oxide finish. So far i only experimented with used vacuum pump oil not a true water displacing oil or oil with corrosion inhibitors added to it. My worry with "proper" black oxide oils is that they may be a mixture of oils and solvents, which would separate under vacuum. I see the black oxide oils advertised as "dry to touch" which tells me that they have solvents in them, which evaporate at STP. Can anyone recommend a "proper" black oxide oil which can survive vacuum? My worry with continuing using use vacuum pump oil is that the vacuum pump oil is hydrophilic, so it will absorb moisture from the atmosphere and bring it into black oxide finish, ultimately doing the opposite to what it is intended purpose is in the oxide finish.