View Full Version : Reverberatory Furnace

02-26-2017, 07:20 PM
I have been researching the reverberatory furnace lately, and looking at various designs. My understanding of this type of furnace is that it produces a consistent heat on all sides of a boiling flask or retort body.

First, I'm curious if this is the correct definition.

Second, has anyone tried the "coffee can forge" as a reverberatory furnace? It's commonly used for metal-smithing, and I've seen some which are designed for refining gold and silver.


The image is what I have in mind for the basic design/structure, but I would make a few adjustments. Thicker walls, a lid for the flask neck, and maybe a second fuel source if the furnace heats unevenly.

02-26-2017, 07:55 PM
I've got a lot of experience with these improvised furnaces, they are the ones I use the most. I make them out of steel cans of several sizes (the biggest one was made out of one of those large steel garbage cans that are still used in many houses; the smallest one was out of a large can of split peas.) They are usually employed for experiments involving high temperatures with crucibles or cementing pots, but they certainly can be adapted to work with distillation flasks/bottles. Just be careful with the heat regulation or the glass will melt. It is better to do like the old-timers did and apply a generous coat of a refractory paste on the part of the glass vessels that are going to be exposed to the intense heat, that way if the glass actually melts, the refractory coating will hold it and prevent it from falling to the bottom of the furnace, thus making a mess of it, which will have to be repaired.

02-26-2017, 08:51 PM
In the reverbatory funace, the fire exhaust gases come in contact with the substance being calcined. This may play an important role for some operations.

02-26-2017, 09:07 PM
Interesting, Mr. theFool. I'll have to consider that for the calcinations. Maybe I can set it up to take multiple fuel sources -- propane and charcoal with a blower instead of a torch head... thanks

02-26-2017, 11:09 PM
Just be careful with the heat regulation or the glass will melt.

This is something I hadn't considered. Thanks.