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Joss Research: Ceramics: Glazes: Copper Red

Ancient Nanotechnology:

(2004 March 13)

The Chinese have been making wonderful red glazes with copper in them since at least the mid-1400s. There have been various versions at different times, and the history is quite interesting. (There is a fine chapter on copper colorants in Chinese Glazes, by Nigel Wood.) It turns out that the red color is an early example of nanotechnology: it is caused by a colloidal suspension of copper nanocrystals, some tens of nanometers on a side. (I think they range from ~20 to ~200 nm across, but don’t quote me.) Richard Zsigmondy got a Nobel prize in 1925 for achieving a systematic understanding of colloids; he invented the ultramicroscope in the process of his research.

Copper Red glazes are notoriously difficult and fickle. It’s debatable whether this is inherent, but there’s no question that it’s The Usual State of Affairs. I started trying to make a decent, noncrazing Copper Red in 1996 or 1997, and have made Copper Gray, Copper Grayish-Pink, a color that is probably the one the ancient Chinese called “Mule’s Liver”, and various other wretched failures. I’ve even made one that wasn’t too bad — it came out a rich purplish red. (Darker

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Joss Research: Vacuum: Gross Leak Detection Techniques

A Joss Research Institute Informal Report:

Using an iPhone to Detect Gross Vacuum Leaks
and Making an Ultrasonic Sniffer for Smaller Leaks


(30 January, 2000)

I am debugging a largish nitrogen laser head that I have just built, and I wanted a good way to find the vacuum leaks that seem to be inevitable with any device of this sort. It is often possible to use a stethoscope with a small-diameter tube as its probe, but I have sometimes find it difficult to get good results that way, and last night it occurred to me that I should be able to use my iPhone with a hands-free device. (The opening for the microphone is no more than a millimeter across, and it is on a very small pod that sits on one of the earbud wires.) Rather than try to listen to the sound, however, I thought I would use an appropriate application to visualize the sound. (There are several of these; I chose one called Spectrogram.)

Sure enough, this technique is positionally sensitive, and at least for moderately large leaks it is quite good. As I continue working on this head I will have to deal with

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Joss Research: Vacuum: A New Manifold for the Roughing Pump

A Joss Research Institute Informal Report:

Construction of a New Roughing Manifold


(09 January, 2010, ff)

I am debugging a hollow-cathode laser head that I recently built, and having some trouble getting it to pump down to a suitable level. A good part of this appears to be an outgassing issue; silicone rubber caulk may not be particularly suitable for vacuum use, even at the minimal vacuum levels involved here. I have constructed a new active section for the laser, with epoxy joints; but in the meanwhile I also wanted to improve the performance of our little vacuum system in a general sense, and to change the manifold from a tangle of polyethylene tubes to something more recognizable. The poly tubing, on its own, pumped down to about 60 mTorr, which is not much of a vacuum even with just a forepump. (I have seen this pump reach 2 mTorr on the bench, running straight into a thermocouple gauge.)

Here are two photos, showing the initial version, before I added a connection to the laser:

           

(The Baratron tube [grayish blue cylinder with narrow red and silver band] is resting on a gray box that is not part of the » Read the rest

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Joss Research: Vacuum: Diffusion Pumps

A Joss Research Institute
Informal Report:

Three Diffusion Pumps
and a Small Surprise


(13 September, 2008)

The Balzers Diff 650

This is the oldest of the three diffusion pumps that we seem to have here; it was recently given to us.

                       

As you can see, it is designed to pull 700 Watts at 110 V; I have no idea how much fluid it takes, or even what the proper fluid is.


The Big Varian in the Vacuum-UV Spectrometer

This pump actually seems to have a gatevalve on it, but I don’t think there’s a roughing pump in the box with it. It appears to have about a 6″ throat.

           


The Leak Detector

We seem to have a partly-disassembled leak detector. Here are some views of the guts:

           
           

The label is scratched up, and a bit difficult to read; the pump is a [rather old] Edwards SpeediVac 403A. It is water-cooled, has a 4″ throat, takes 100 cc of fluid, and pulls 500 W at 240 V. (I can make 240 V with a step-up transformer, and the heater shouldn’t care about the frequency.) I have checked the heater; it has reasonable resistance, and is not shorted to the case. So

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Joss Research Institute Web Report #20: The Hunt for Red Tenmoku

TJIIRRS: Number 20

Red Temmoku: A Difficult Glaze

(2010.0712)

When I first started making my own glazes, I read Robert Tichane’s book about Ash Glazes. In his discussion of Jian teaware he mentions having been given a chip of glaze, and (assuming I remember this correctly) he says that in transmission it was a brownish yellow color. Jian teaware, however, looks almost black. This is because the bowls are made of a dark stoneware-type clay, and a brownish yellow glaze looks really dark on them; I am using porcelain, and a glaze of that sort is not anywhere near as interesting, at least to me.

The Metropolitan Museum of Art, in NYC, has a photo of a particularly lovely “Hare’s Fur” piece on its Website. As you can see, aside from the crystalline formations that give it the appearance of fur, the glaze appears quite dark.

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Joss Research Institute Web Report #19: A Voss Electrostatic Generator

TJIIRRS: Number 19

A Voss Machine

(04 July, 2007)

There are lots of interesting designs for electrostatic generators. The most common and familiar type of “influence machine”, these days, is the Wimshurst machine, but that has counterrotating disks, and is slightly complex. This is not to say that Wimshurst machines are really all that difficult to construct (see this page by Jarrod Kinsey for an example); but I decided to go with something simpler for now. This page records my construction of a Voss machine, with photos and with my comments and occasional suggestions about the various issues I encountered.

I have also provided a link (near the bottom of the page) to a site where you can find a lot of information about many kinds of electrostatic generators.

In its simplest form, the Voss or Töpler-Holtz machine has only a single rotating disk, and when correctly designed and constructed it provides more than adequate performance. In fact, multiple Voss machines (another example) were sometimes used at the turn of the 20th century to power X-ray machines.

(Unless they have corrected it, btw, there is an error in the description of the first photo on the Kenyon page. It

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Joss Research Institute Web Report #18: Handy Techniques for Fountain/Calligraphy Pens

TJIIRRS: Number 18

Fountain / Calligraphy Pen Techniques:

Refilling Disposables
and
Shaping Nibs

(28 February, 2008)

Last year, I was given two Pilot “Varsity” fountain pens by the redoubtable Kludge. Here’s one of them:

These pens have stainless steel nibs, which should, in principle, last for a number of years; but after you use them for a while you discover that there is no obvious way to refill them — when they run out of ink, you are supposed to throw them away. While I admit that there are good arguments in favor of a few (very few!) disposable items, for the most part I hate disposables, and I find this extremely offensive.

I took a quick look at the structure of the pen, but I did not find any obvious point of entry. (Gareth Branwyn, who was kind enough to note this page on the Make Magazine blog, however, tells me that it is possible to remove the point.) Then, while cruising on Simon Quellen Field’s excellent Science Toys Website, I came across something that seemed like a great idea: Simon uses a common canning jar as the chamber of a simple vacuum system. As soon as » Read the rest

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Joss Research Institute Web Report #17: More Explorations in Translucency

TJIIRRS: Number 17

Further Explorations in
Translucent Porcelain

(25 December, 2007, ff)

This page describes my ongoing attempt to make porcelain that is more translucent than bone china. This, no surprise, is a nontrivial endeavor. Before I came to Joss Research, I had already developed a porcelain that is about as good as decent English bone china, and is easier to work with. It looks about like this:

That isn’t bad; in fact, it is slightly more translucent than Southern Ice at the same thickness, and as you can see, it is plastic enough to throw on a wheel. (I have to do things to it to achieve the required degree of plasticity, but we can get into that later.)

I have continued to think about the issues involved in translucency, and have reached some conclusions. A few things appear inescapable; for example, it is quite clear that bubbles and voids are not going to be good for translucency. The refractive index of aluminosilicate glass (the majority constituent of porcelain) is in the vicinity of 1.515, whereas the index of air is close enough to 1.000 as to make no difference to us as potters. Any bubble or void

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Joss Research Institute Web Report #16A: Preliminary Attempt to Build a Stainless-Steel Hollow-Cathode Helium-Argon Laser

TJIIRRS: Number 16A

An Initial Attempt at Building a Hollow-Cathode He-Ar Laser


1. Design Considerations

(~22 October, 2010, ff)

This page describes the process of constructing a small hollow-cathode laser that has argon ions as its active medium, and uses helium as a buffer gas. My objective is to make the laser relatively easy to construct and operate, and to avoid parts that are expensive, difficult to obtain, or require much machining.

I also hope to use this platform to test a helium-iodine mixture, so I will be using stainless steel end fittings, as iodine reacts with brass. If you decide to build one of these and you do not intend to put iodine into it, you can use brass fittings.

This laser should operate at 476.5 nm, close to the usual blue argon wavelength (488.0). The gain is likely to be relatively low, perhaps 6% per meter, but He-Ar hollow-cathode lasers with active regions as short as 10 cm have been successfully operated, and the active length of this prototype will be 30.5 cm, so there is a decent chance that it will be feasible. I expect to use ordinary argon-laser mirrors, which should provide adequate feedback if

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Joss Research Institute Web Report #16: DIY Hollow-Cathode Lasers

TJIIRRS: Number 16

A Hollow-Cathode Laser Design for the Do-It-Yourselfer

(16 February, 2010, ff)

Introduction/Abstract

(22 October, 2010, ff)

This pageset deals with two sorts of hollow-cathode lasers: metal vapor (excluding iodine for the moment), and argon or iodine. The designs are nearly identical, except that the metal vapor lasers must provide metal for the discharge, and in a hollow-cathode laser of this sort the metal is sputtered from the electrodes; argon and iodine are introduced with the buffer gas, which is helium. (Iodine has been classed as a metal vapor laser, and in fact I believe it was the first laser of the helium-metal type to be described in the literature.)

My hope is to generate designs that DIYers can reasonably hope to build and operate. The first one will probably operate with a mixture of helium and argon. If I can get that to work well, I will probably try it with helium and iodine. After that, I hope to move to helium and zinc, perhaps with a small amount of argon to help sputter the zinc into the discharge, and finally helium and copper, also possibly with a small amount of argon.

[Note,

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