Big Smelter project. Smelting Furnace Lining, Drying,Testing Part 3 of 3

This is the last part of Big Smelter project. I’ll finish this metal melting furnace by making refractory lining, drying, firing and finally testing. I can say that it’s my longest DIY project. It took me little more than 5 weeks to finish this big smelting furnace. I tested it by melting aluminum, brass and copper. The furnace passed all tests and got just minor damages.
1. The final refractory mixture formula is 50% of grog, 43% of fire clay and 7% of graphite dust. We should mix all the components and add some water. A lot of people during making refractories recommend to use less water. I don’t agree with that. In my opinion, it’s important to use a lot of water. I tried to use a small amount of water during lining the lid and it worked very bad.
2. The next stage is drying. I’ve decided to use a bulb as a source of heat. The temperature outside was from -5 °C to +8 °C (from 23 °F to 46 °F), and rain, snow from time to time. Therefore, it wasn’t easy and quickly to dry 50 kg (110lbs) of refractory material.
3. When furnace lost most moisture it was a time to start firing. I made it very slowly. In the beginning I even didn’t blow the air inside. And after some time I could start blowing the air.
4. During the final test the furnace was working during an hour. That’s usually enough time to melt copper.
I’m satisfied with the result. Now my home foundry allows me to melt and cast metals when I need it and I don’t need to fix the furnace after every melting.

If you haven’t watched part one and part two of Big Smelter project, please check this videos using the links below:

Part 1. Smelting Furnace. Project "Big Smelter". Making Outer Skin:
Part 2. Big Smelter project. Making the Lid:

In addition, you can check my other DIY (How to make) videos:
Metal melting furnace from a scrap - building guide:
How to make a crucible:
New blowpipe - metal melting furnace upgrade: