Heat Treating with alcohol/ethanol

Hi all,
I recently watched the video below and was wondering if anyone can give me a whole lot more information on the process and its effectiveness, how to do it, etc.?

Dan Gelbart Workshop Tour HD - YouTube
23:35 minutes in...

This was the first time I have heard of the ability for ethanol to form a gaseous atmosphere which can protect the contents of a kiln from oxidising/de-carbonising. It seems an extremely cheap method of protecting parts for heat treating.
I recently bought a kiln but I will have to fill in the air gaps if I am going to try this process as there is a very poor seal around the door.
I imagine that you only need a tube that enters at the top of the oven and that gravity just drip feeds the alcohol in (probably as a gas by the time that it enters such a hot environment)?

Anyway, I would love to hear thoughts and opinions on the matter.

Cheers!

My little kiln has a top entry port for gas and I’ve been wondering the same thing since seeing the same video. Seems like the entry tube would be very hot but maybe that’s okay as long as it’s isolated from air exposure?

Oh, one correction is that the liquid is methanol, not ethanol.

I do this often. The alcohol creates a reducing atmosphere. Natural gas or propane also works. Too much can leave carbon on the surface. Way too much poses a fire risk.

The long-term risk is degrading the heating elements. They are protected by an oxide film that is reduced by the hydrocarbon atmosphere.

The picture shows a 304 stainless canister sitting on a gas distributor plate. The plate is actually two plates welded together with a small inner space. The top of the plate and bottom of the canister have corresponding holes that allow gas to filter over the parts in the canister. The stainless canisters are just cheap kitchen ware. The outside of the cans oxidizes quickly. The inside remains in good condition. I use a can for about ten heats then scrap it for a new one. The distributor plates are heavier stainless. They are oxidized but have lasted for many cycles.

Steel parts come through with heat marks but do not have scale on them. I mostly use natural gas or nitrogen. Run the gas fast for a few minutes then turn the flow down very low. Some activated charcoal in the can together with the parts also works. Do not use regular lump charcoal because it leaves a tar-like film behind.

Make certain the parts are perfectly clean. Any oil will turn into a hard black deposit. I often wash the parts just before heating, rinse them in methanol to displace the water, shake the excess off and put them in the can wet with alcohol. Then straight into the oven. This prevents flash rusting.


You can also make an active flux with some kaolin, boric acid and iron oxide. It bakes on the part and protects it at temperature in open air. I do not like this method because it is very difficult to remove from tight corners or threads.