Here you can read about my work and experiments with as different things as prehistoric iron smelting, computer physics simulations, and building a 21,5 meter (70.5 feet) replica of a viking ship.
Today I dried the smelter with fire. No serious cracks appeard in spite of the clay mixture not containing any horse manure. It seems letting the smelter dry in the sun for a few weeks does the trick just as good. I’ll take some pictures of it in the morning with my new olympus tough camera.
Today will be spent in bed, trying to get some work done under the hood of this blog.
Home after 5 intense days of viking ship construction. Sleeping outside in an igloo-tent turned out to be less of a good idea. Instead of spending today outside in the beautiful weather building the smelting furnace, I’m stuck in bed with a terrible man-cold. The best I can do is spend some time on updating this blog. I’m hoping to be able to build the furnace tomorrow. Saturday I’ll return to the ship, cold or not.
Here’s a link to our ship guild’s blog. Currently I’m mostly involved in getting the production of wooden nails up ‘n’ running. As you can see on the photos they’re beeing made on an old school 1930′s metalworking lathe. That’s what happens when you ask a smith to do woodwork.
I’ve done a number of tests on different clay to sand ratios and have refined the mix a little. Yesterday I made a number of small clay balls with different mix ratios, which were dried and heated at full blast for about 10 minutes in the smithing hearth. The temperature was 1200 – 1400 degrees celsius, which is the same as in a running smelting furnace. The ball made of pure brick clay swelled up like a marshmallow and turned into a foamy, black glass. So that’s a no-go I suppose. The other balls had a sand content of 50% or higher (by volume). Despite of the intense heat they never really baked together but stayed crumbly and porose. On the positive side, they didn’t swell up but kept their original size. After testing a few ratios in between these extremes, I found a decent mixture that bakes together nicely without swelling up. The final mixture I’ll be building the furnace of is 7-8 clay bricks to one bucket of white sand (ratios are esimated, exact ratios by weight are coming up later).
Last night I roasted the first batch of bog iron ore. Nice quiet evening at the fireplace, watching the constellation of Venus, Jupiter and the new moon. The ore comes mostly in 5 – 10 cm flakes that are ideal for roasting without putting out the fire.
During the weekend I’ve made a large (1 m in diameter) fireplace encircled with stones next to the furnace building site. I have spread a 5 cm layer of ore on the ground inside the fireplace to prevent the roasted ore from beeing mixed with dirt when it is dug out. I also got a really cheap second-hand 650 Watt Makita drilling machine with a mixer. It does a decent job turning wet bricks and sand into soft furnace clay mixture. The ratio is 5 or 6 bricks (about 4.4 kg each, including water) to one bucket of fine, white sand. I’ve decided to leave out the horse manure, partly because there’s no evidence of any kind of fibre in prehistoric furnace findings, partly out of plane curiosity. As opposed to most of my earlier experiments I now have the time to let the furnace dry out in a natural, slow pace. The dry, sunny spring weather is perfect for the job. This should minimize the amount of cracks, making the addition of fibre obsolete.
(Also, I’m still having a little trouble with my photo album plugin, so I might have to delete everything and start over…)
Today I trucked the last load of clay home. I had to pick the freshly molded bricks one by one out of the drying rack at the local brickyard – interesting place with lots of conveyor belts, turning wheels, steaming pipes and of course an old smithy. Glad I got to see it. Later I dug out the last dirt from my back yard pit, revealing a thick layer of fine, yellowish white sand, untouched since the last ice age. Really good for a refractory furnace clay mixture. After sunset I got a trailer full of mixed size rocks from a small neigbouring town. They are for the ore roasting fireplace and for the furnace foundation. Now all materials are home, I’m ready to build.
Okay, winter’s gone and I’m running out of excuses for not building that smelting furnace I’ve been talking about for the last year or so. Yesterday I got 400 kg. of really nice clay from the local brickyard, and tomorrow I’ll get the next load. Hoping to get the furnace finished over the weekend. Horse manure, tools, sand, charcoal, adjustable air pump, firewood, duct tape… it’s all ready. And enough premium bog ore to sink a ship. This is going to be good.
At last I found the time to ditch the old static webpage and install WordPress. The next few days I’ll be experimenting with themes and setup, and hopefully find the time to upload some material.
