Using the Raku Process to Show Oxidation-Reduction

A little while ago, I went looking for a video to explain the oxidation/reduction aspects of raku so I could assign it for my students to watch while I was out of the classroom for a day.

Sadly I didn't find one, but I did come across this video from the inaugural ASM teacher camp in Butte, Montana. It doesn't explain the redox aspects of raku - though the title suggests that it might - but it does include your friendly, neighborhood blogger in his orange polo shirt (ASM-branded, natch), and jeans.

Because the video doesn't explain the science, I'll give a quick version...

• We use a clear glaze into which we mix oxidized metals (cobalt oxide, iron oxide, copper carbonate, nickel oxide, etc). Each glaze gets just one of those oxidized metals.
• The pottery is taken out of the kiln while it's hot - somewhere around 1050 ^oC. At that point the glaze is molten, allowing oxygen to leave the glaze.
• The hot pottery is placed into a metal can with something flammable. In this situation we're using torn up newspaper.
• The torn up newspaper catches fire and starts to consume the oxygen in the now-sealed can.
• The carbon and hydrogen from the paper continues to 'search' for more oxygen, so it reduces the metal in the glaze and takes the oxygen from the oxidized metals. (This only works if the pot is hot enough for the glaze to stay molten in the reduction environment.)
• The glaze cools, sealing in the now-reduced metal within it, leaving - hopefully, if everything works right - reduced, shiny metal in the glaze.
• The pottery is quenched in water to lock in the final version of the metal within the glaze - either reduced or oxidized metal.

You can see lots of versions of raku pottery on other blog posts.

Grow Copper Crystals with Electricity

As always, be careful out there, folks. This experiment does involve running electricity through a solution.

This process does seem to result in some really pretty crystals.

And I'll admit that I kind of enjoy the simple, non-mugging style that the Backyard Scientist has gotten away from over time.

Making and Casting (Principles of Metallurgy)

This is a very information dense video explaining...

• where iron ore comes from and what it contains
• how blast furnaces purify iron from ore
• forming the iron from the furnace into steel
• arc furnaces melting and purifying already formed steel
• further steel refining
• casting of the steel into shape via...
• sand casting
• continuous casting
• ingot casting

This would be a great summary of the steel processing processes in class.

There's not much exciting to watch. I'm keeping the tone of my writing this week in line with the tone of the video so you know what to expect.

Thank you for reading.

Ceramicist Uses Science To Create Sculptures Inspired By Nature

I stumbled upon the above video in searching for totally different ceramic stuff on YouTube, but I was immediately taken by the magnetic stalactites that the artist is creating in the video still.

He mentions in the video that he creates them by using a magnetic clay of his own devising between two super-strong magnets. 

Then the video goes through him using his ceramic as an electrode - which inherently doesn't make sense to me since ceramics are naturally non-conductive - in what appears to be a copper (II) sulfate solution and using a current to grow copper crystals on the ceramics.

Then the gold, pocked inner surface of other ceramic bowls showed up, and I was blown away with the beauty.

So I went searching the guy out to see just how much one of his pieces would cost me - assuming fully that I wasn't going to be able to afford it.

My first hit was for a reporter on NPR's MarketPlace with the same name, who clearly couldn't be the same guy. Then my second Google hint was the same guy's Twitter feed where he describes himself as "MarketPlace reporter, ceramicist". I then found his ceramics-focused Instagram account and knew I had the right guy.

Apparently this dude has a few disparate interests.

Titanium - The Metal That Made The SR-71 Possible

 Hey there, Brian. Good to hear you again.

I recognize those material selection diagrams at 1:35. I've posted about similar diagrams before.

This video does a great job exploring the tradeoffs among strength, weight, cost, and properties in choosing a material. In this case, it's mostly about the tradeoffs guiding when we do - and don't - use titanium.

It also covers some of the concepts of chemical and electrolytic reduction around 5:00 - and states that we don't use either of the traditional processes to purify titanium. It's amazing that anybody ever figured out some of the more complicated metals processing...um...processes. They're so remarkably complicated.

We also get an application of accidental galvanic corrosion at 8:30 where the cadmium-plated tools were leaving trace amount of cadmium on the titanium.

Titanium really sounds like a pain in the tuchus to work with.