We have used heated "sweat boxes" for years to accelerate the rusting process, but has anyone ever added oxygen to a sealed sweatbox to hasten the process? Oxygen makes up 21% of the atmosphere, so if I quadruple that concentration in the sweatbox would I cut rusting time by 75%? I'm thinking of using one of those long, plastic storage containers with an airtight top, then adding a saturated sponge, treated gunmetal and finally a good blast of oxygen from my welding tank before sealing the lid. This container will then be placed outside in full sunlight to get free heat. If it works I should easily be able to get 6 passes a day and drastically cut blueing time.

I had never thought of that, but I have toyed with the ideas of adding hydrogen peroxide to the boiling bath, to increase the O- ion concentration, as well as lightly "pre-etching" the metal with naval jelly, to allow it to get a nice even iron oxide (red rust) coating prior to boiling. I was thinking that the latter would decrease the number of passes you would need to get a good rust blue, while the peroxide would give you a better final finish.

Todd

Bobster,

Increasing the oxygen in a box like that could very well start an extreme (though short) fire. Oxygen is something to be careful around.

I would say ozone, using one of those electrostatic machines found in health store to continuously transform oxygen into ozone. With ozone, there's no need to boost oxygen content in air, besides, ozone is a much stronger oxidizer than plain oxygen.

and nascant(sp) oxygen is even worse... for a reason... roger knows..

But, remember rust is oxidation, and, in effect, fire.. with enough o2, it will be a flame...

use the hot water method, me thinks
jeffe

DOH!

I do not know how I managed to goof like that, I didn't read far enough...plastic. Ok.

Bobster, May I respectfully suggest (after my way too soon comment) that you try a test. Prepare two pieces of steel exactly alike (barrel stubs or something) and test them, one with oxy and one without.

Bobster---

I tried it in 1981 at my shop which was at 8050 foot altitude in the Colorado rockies.....it DID work faster, but I had a terrible pitting problem and discarded the idea.

If you sit a sealed container in the sun with a wet sponge you'll almost immediately get WAY too much heat and the water will condense on the metal and the box. That'll ruin the job in a few minutes.

I use a pexiglass box with a 25 watt bulb mounted in one end. A wet paper towel supplies the moisture, the bulb the heat, but I usually have to prop one end of the lid up to keep away condensation.

The arsenals and the factories used a "steam box", but every account I've read says the steam was a one-shot thing only to add water and heat.

If you want 6 coats a day use Belgium Blue or Mark Lee Express Blue. They work very well.

The best rust blue is slow to act.....that's why most custom makers dilute the chemicals some to slow it down. It seems to give a finer finish.

Thanks Jack, you saved me a lot of grief. I'll order some of the Belgian Blue. The plexi sweatbox sounds like a good deal. I have a friend who constructs plexi displays for industry. Maybe he can build one for me with a slanted lid. I might add a vent at the top to release excess moisture as you suggested.