Author archive for Derek

  • Techniques

    Razor trimming

    I’m not sure if double-edged safety razor are still available in the West, but here in Jingdezhen they are an essential trimming tool.  These razors are thin, sharp, and most importantly flexible.  Great for wheel-trimming details on small forms, or for scraping hand-built objects.  The most used brand is Flying Eagle.  I get the more expensive stainless steel ones.  At 5RMB for a 5-pack, each blade is about 15¢ USD.

    Two brands of safety razors available in China

    Using a Dremel or similar tool, edges of both thin and thick razors can be ground for specific uses, like scraping glaze off these plate feet.

    A Dremel tool was used to create a notch in this blade for use in scraping glaze off this unique foot.

  • Glazes

    Glaze Transparency Test

    Recently I’ve been wondering if there’s a reliable way to test glazes for transparency.  A method that would allow one to compare results from different firings and glaze types.

    Paint manufacturers have a system for testing paint opacity that uses a black and white card from which a contrast ratio can be calculated. The primary manufacturer is Leneta.

    I couldn’t find any parallels in the ceramics industry.

    I wanted to try a similar method using porcelain (white) and stain/colored porcelain (black), adjusting the results to account for the fact that our whites and blacks are not pure.

    Paint Opacity Chart from Leneta

    Using my whitest porcelain, I created a colored slip adding 8% of a local black stain.  (Ideally one would use a standard mason stain.)  Adding Darvan, I made a thin slipcast slab that I then cut into small squares.

    Cutting square slabs of stained porcelain

    Using the same casting porcelain I made a thicker slipcast slab which was then cut into square test tiles.  The black stained squares were then applied to each test tile and rubbed flat.  Finally, the tiles were bisque fired in the hopes of minimizing contamination of the glaze when dipping.

    Test tiles after adding black-stained squares.

    Two 100 gram batches of glaze were prepared:  Pinnell Clear and Pinnell Clear with added 10% Zircopax.  Using volumetric blending I created tests in 2% increments.  The tiles were dipped in the test glazes.  Ideally, steps would be taken to ensure even thicknesses of glaze.

    Test tiles after firing in reduction to Orton cone 10.

    The fired tests display a nice opacity gradation as zircopax is added to the glaze.

    Unsure of the best way to measure transparency (or opacity) using these test tiles, I tried the simplest approach I could think of.  Adjusting the image to greyscale, I averaged the colors of the white test tiles as well as each black-stained square.  Below are the Brightness levels measured in Photoshop using the HSB scale.  If these tests were going to be made consistent across firings, I suppose one could normalize the photos based on the color of the unfired white porcelain body.

    For the opacifying power of Zircopax relative to this specific test, I created an opacity scale in Photoshop using the 0% glaze as a baseline and then matched the tests to this scale.  According to the scale, a 4% addition of Zircopax opacifies the glaze by 30%, while a 10% addition of Zircopax opacifies the glaze by 70%.  I’m probably vastly over-simplifying things.  For instance, I didn’t take into account the fact that the entire test whitens as Zircopax is added.  Also, there will probably be few times in ceramics where there is a neat linear relationship, for instance adding 14% Zircopax to the glaze won’t necessarily get me to 100% opacity.

    Below is a closeup of the black squares.  If I had made these tiles more consistently, with a crisp, straight border between the black and white porcelain, it might also be possible to compare diffusion.

    Close-up of colored squares.

  • Antiques

    Wanli Pheasant

    Blue & White pheasant head on a Wanli dish.

    Single photo from iPhone with Eyeskey lens.  More details here.

  • Glazes

    Jun

    A Jun glaze on stoneware from the last kiln

  • Uncategorized

    Sashi-ire hana no futami 挿入花の二見

    Images of Japanese flower arrangement from the woodblock-printed book Sashi-ire hana no futami (挿入花の二見) made in 1798 by the amazing Katsushika Hokusai.

    Images generously made available by the British Museum.  I have cropped and adjusted levels of the original scans.  These are full-sized images, right-click to save.

    Two beautiful books of modern Japanese flower arrangement by Kawase Toshiro:

    The Records of Flowers in Four Seasons

    One Day One Flower

  • Uncategorized

    Kawase Hasui

    A wonderfully romantic view of a Japanese pottery.  Link here.  Ukiyo-e.org is an amazing collection of Japanese woodblock prints.

    Kawase Hasui

  • Craft

    Brother Thomas Bezanson

    Brother Thomas Bezanson

    From Creations in Clay, a book of essays and photographs of Brother Thomas Bezanson’s work:

    For many years of my work as a potter I was concerned with learning the skills and technologies proper to the potter’s art.  I was focused on looking back to accomplishments of the past; I was open to those men and women who shaped the tradition of ceramic art.  They were my teachers, by necessity of my ignorance.

    Then at some point in a time out of time they left me standing, so to speak, in a dark forest where their ability to guide me came to an end; there was no longer a path of the past to follow.  There were no paths at all, except the one I was called to make for myself if I did not want to be just another derivative, condemned to repeat the past, or bootleg from the present.

    At this juncture I gradually became aware that my new teacher and best guide was my own work itself.  It led me into myself, into my own inner experience.

    Porcelain vase with copper red glaze

    Wintermoon (Vase)

    Vase

    Hexagonal platter

    Jar with cover

    Tea bowl

  • Photos

    Scanning Test Tiles

    Having purchased a scanner for digitizing my family’s old photos, I had the brilliant idea to also scan glaze test tiles.  I thought I was a genius until Matthew Katz mentioned that he had been scanning tiles for the past ten years.

    Matthew noted that CCD scanners have a greater depth of field, which is great for three-dimensional objects like test tiles.  Because of his recommendation I purchased the Canon 9000F Mark II.

    I’m not a scanner expert and have never calibrated a scanner before.  I already have an X-Rite ColorChecker Classic for photography, and this color card can be used with X-Rite’s i1Profiler (i1Publish) software to create a scanner profile.  Unfortunately, the software license seems to be very expensive.

    I tried Argyll CMS (http://www.argyllcms.com/) but results using the generated ICC profile were worse than the default output.

    Here’s a scan of some test tiles.  I had to adjust the Exposure in Photoshop by about +1 stop.  Notice the reflections on some test tiles that were not flat.

     

    2400dpi scan, 1.3GB TIFF

    Enable large image scans on Canon 9000F Mark II

    The Canon software is really frustrating- by default it wouldn’t let me scan a file greater than a set limit (10208 x 14032 pixels, or larger than 100MB).  I finally found a solution hidden away in the software settings.

    By default, ScanGear won't let you scan images greater than a seemingly arbitrarily set limit.

    1. Open IJ Scan Utility and click Settings

    2. Select ScanGear and check Enable large image scans

    3. ScanGear will now scan files over 100MB. However, you must manually enter dpi greater than 1200, such as 2400, 4800, 9600.

    Comparison with DSLR

    I have a relatively old and cheap Canon EOS Rebel T2i with a 18MP sensor.  In comparison with the Canon 9000F scans, the photos from my camera are smaller.  However, they seem to contain just as much if not more detail and better colors.  If needed I can adjust lighting conditions and camera settings to reduce reflections and adjust exposure.  On the other hand, the scan had some reflections that I could not eliminate.

    It also takes less time for me to take photos than scan at 2400dpi.

    Below are comparisons of the scan and the photos.  In particular, the dark glazes came out very poorly on the scanner.

    Tianmu glaze tile. Canon 9000f Mark II 2400dpi, adjust exposure +1.

    Tianmu glaze tile. Natural light, 18MP EOS Rebel T2i photo

    Ash glaze tile. Canon 9000f Mark II 2400dpi, adjust exposure +1.

    Ash glaze tile. Natural light, 18MP EOS Rebel T2i photo

    Detail of Canon 9000F Mark II scan

    Detail of 18MP EOS Rebel T2i photo

    Conclusion

    In conclusion, while the Canon 9000F is great for scanning old photos and documents, I still haven’t found a way to scan glaze tiles that beats results from my old DSLR.

  • Photos

    Smartphone Microscopy

    Last year I purchased a USB microscope (see article).  It’s pretty fun, but ultimately I was really disappointed by the quality of the images.  The 5MP sensor seems pretty cheap and images have a lot of artifacts.  Furthermore I was never satisfied with the color.

    The best choice would probably be a “real” microscope with a camera adapter.  However, this little hobby of mine doesn’t justify spending a lot of cash.

    There are a few tutorials online for creating your own phone microscope using the lens of a laser pointer.  (I tried this and it worked pretty well, but I never found a way to conveniently attach the lens to the camera.)  Wired’s article Turn Your Cellphone Into a High-Powered Scientific Microscope has a good tutorial as well as background on the scientists who are using cellphones as biomedical devices.

    Fortunately there are now multiple products for sale that make it easier to attach a lens to the phone.

    There’s a former Kickstarter project that looks promising and is shipping, the 15x Micro Phone Lens and 150x Micro Phone Lens. (See my November 2016 update, below.)  In China there are a number of cheap alternatives.

     

    Supereyes Smartphone Microscope (Not recommended)

    I purchased the Supereyes Smartphone Microscope for about $7USD.  The images below were taken with this lens.  Unfortunately the top of the plastic lens is not protected and I scratched it after playing with it for less than an hour.

    The images from the iPhone with attached lens look much better than my USB microscope.  The photos below were taken in natural light.

    The lens attached to the iPhone. On top is a plastic cover which is easily scratched. I removed it with a Dremel.

    View of ruler through attached iPhone lens

    After zooming in with fingers (digital zoom)

    Qing Dynasty Guan glaze

    Qing Dynasty Guan glaze

    A Wanli dish shard

    Blue & White birds in the Wanli shard

    Teadust Glaze

    Iron Red (Kaki) Glaze

    A celadon glaze I'm working on

    Eyeskey 12x Micro Lens

    It was only after using the Supereyes lens that I realized it’s horrible design (does not fit on camera lens, slides off the camera lens, plastic cover easily scratched, etc.) that I bought another cheap microscope lens, the Eyeskey 12x Micro Lens (also about $7USD).

    The Eyeskey model is designed much better.  An adapter slides perfectly over the phone and the lens is screwed into the adapter.  The plastic tube that is visible using the Supereyes lens is not a problem here.  The magnification is also greater than the Supereyes lens.

    (Unfortunately I could not find this model for sale in the West.  However, I think the 15x Micro Phone Lens might be even better.)

    The Eyeskey lens with phone adapter. Much better design than the Supereyes.

    Viewed using the Eyeskey lens. Notice that there is no circular tube visible.

    Zooming in with fingers (digital zoom). Magnification is higher than the Supereyes model.

    Another Iron Red glaze

    Strange rivulets and eyes in a Tenmoku glaze containing Rice Straw Ash

    A Jun celadon glaze on black stoneware

    Porcelain stone and wood ash with carbon trapping and iron spots

    Coleman Kaki on porcelain, cone 9

    Comparison of Supereyes and Eyeskey Lenses

    Supereyes lens

    Eyeskey lens

    Supereyes lens digital zoom

    Eyeskey lens digital zoom

    Microphonelens 8x Macro & 15x Micro Lens

    On a recent trip to the US I ordered the Microphonelens 8x Macro lens and 15x Micro lens.  These lenses are different than others- they simply stick to the phone’s camera lens and have no outer support column.

    In use, I found it more difficult than the other lenses because I could not directly rest the lens at the correct distance against the viewed object, resulting in more blurry photos due to camera shake.  Also, while the micro lens is designed to stick on the phone lens it falls off if touched and gets dirty in the process of handling.

    These drawbacks are forgivable, though, as the quality of the images seems superior to either of the other lenses I tested.  Also, the lens cleans up easily with just a bit of pure or soapy water.  The soft material also scratches less easily than hard plastic lenses.

    For viewing glazes, both the 8x and 15x lenses are useful.  I would recommend the 15x (although of course it has a narrower depth of field).

    The microphonelens case with lenses

    The 15x microphonelens lens on an iPhone

    8x microphonelens macro lens

    8x microphonelens macro lens

    15x microphonelens micro lens

    15x microphonelens micro lens

    Blurred image, lens just needs cleaning in a bit of water.

    Stitching photos

    I tried the iPhone’s panorama feature but it did not work.  The iPhone panorama gets confused.  However, you can take multiple photos (moving the camera slightly each shot) and then stitch the photos together using software.  Adobe Lightroom (Photo Merge->Panorama) and Photoshop (Automate->Photomerge) have this feature , however it takes a lot of time and seems limited to 100 or so photos.  I tried a free program called AutoStitch that worked pretty well.

     

    AutoStitch image stitch of Iron Red (Kaki) glaze. Autostitch options: Multiband->Blending Bands = 2 (default). You can see a lot of ghosting where images weren't aligned properly. Photos from Supereyes lens.

    AutoStitch image stitch of Iron Red (Kaki) glaze. Autostitch options: Multiband->Blending Bands = 10 (needed over an hour to process 78 photos). Photos from Eyeskey lens.

    AutoStitch image stitch of crazy Tenmoku iron glaze by Kimura Moriyasu. Photos from Eyeskey lens.

    Photoshop photo merge of Song dynasty saggar with natural wood ashes. Photos from Eyeskey lens. Photoshop seems to do a better job than AutoStitch (in default mode).

  • Family

    Yangchow Internment Camp

    These are some of my great-aunt’s photos of Yangchow camp.

    She notes the duration of internment as starting on 13 March 1943 and lasting until 6 October 1945.  She was housed in Yangchow Camp “C”.

    An interesting history of the camp can be found on Frank Waller’s website at http://www.haikufrank.co.uk/memories_of_yangchow.html

    Some of these photos and more can be found on the Australian War Memorial website.

    If you have information regarding these photos or would like high-resolution versions, please contact me.

    As captioned by Frank Waller, House no. 2 (Government house) and house no. 3

    Hospital, House #1, Camp C

    House #2, Camp C

    Possibly House #3, Camp C

    As captioned by Frank Waller, House #4, reserved for families.

    Internees at Yangchow Internment Camp

    The Belgian Group

    The Hospital

    The Wash House

    The Bakery

    The Goatery

    The Hospital & Kitchen

    Captioned End of War in my great-aunt's photo album. Relief supplies parachuted into Yangchow camp at the end of World War II. In the background is Yangchow's city wall. Frank Waller's article suggests these drops began around mid-September of 1945.

    Main Gate of the Yangchow Camp. Possibly after VJ Day.

    Sometime after VJ Day, the raising of the Allied flags over Yangchow Camp.

    A gathering of the internees, possibly after VJ Day.

  • Glazes

    Spraying Glaze

    Spraying glaze is a fairly complicated process.  There are craftspeople in Jingdezhen whose only job is going from workshop to workshop spraying glaze.  There are so many factors involved with spraying (the type of work, thickness of work, type of glaze, glaze consistency, air pressure, spray head type, even weather) that it requires years of experience to be able to master the art.

    I hope to slowly add to this article in the future.  For now I will just lay out the basics of how I spray glaze.

    The Spraying Booth

    My spray booth is made locally in Jingdezhen.  It’s a simple stainless steel frame with glass.  A large fan is attached to the back, sucking out particles.  Water is pumped from a bucket through a hose that leads to the top of the booth interior.  The water is channelled along the top of the glass and then exits through small holes, forcing the water to run down the glass, washing away glaze.  The water finally exits through a hole in the bottom of the spray booth, pouring back into the water bucket.

    A typical Jingdezhen spray booth

    A gap between glass and stainless steel reservoir evenly distributes water down the glass.

    The fan at the back of the spray booth blows out particles.

    Detail of the fan label

    The pump sucks water from a bucket and up through the spray booth.

    Detail of the water pump

    Inside the booth I place a large plastic basin for collecting glaze. Inside the basin is a turntable.

    On top of the turntable I place a plaster disk. The added weight results in more even turning, while the plaster absorbs glaze. A notch in the plaster helps with counting revolutions. After spraying, glaze can be scraped off and collected.

    The Air Compressor

    I have an old, noisy air-tank compressor that I rarely use.  I much prefer the Jingdezhen method- a cheap magnetic air compressor used in fish tanks.  I’ve used my current compressor for six years and it still runs great, with no need to worry about adding oil or filtering the outgoing air.

    I’ve found that a 520W compressor is ideal.  In the past I had a smaller compressor that didn’t spray as well.

    The sprayer does a great job of mimicking traditional Jingdezhen glaze spraying using just the breath.  A normal air compressor using a paint sprayer head will give you a finely atomized cloud of glaze resulting in a powdery glaze application.  But a traditional mouth sprayer connected to the fish tank compressor will give you relatively large glaze droplets that soak into the clay, leaving a more compact glaze application.

    The fish tank compressor method also sprays less glaze into the air.  I often just run the water pump and leave the booth fan off (but of course I wear a good respirator).

    Note that this type of spraying results in more water being absorbed into the ware.  Especially for thin pieces, care needs to be taken not to overload the ware with water.  I usually spray the outsides one day and the insides the next, giving the ware sufficient drying time in-between sprays.

    If while spraying you notice the glaze stays wet and shiny on the surface it means you are either spraying too close or have already reached saturation.  This is bad.  There’s a good chance that the entire glaze layer will separate from the ware.

    My air compressor is actually just a cheap fish tank pump. It's much quieter than normal air-tank compressors.

    Detail of the 520W fish tank magnetic air pump, rated at 0.04MPa (approx 6PSI)

    The spray canister is attached via rubber hose. A shut-off valve to controls air flow.

    Mouth sprayers

    The glaze sprayers widely used in Jingdezhen were originally meant to be sprayed using only one’s mouth.  Since then, the mouth stem has been modified from conical (larger end towards mouth) to tapered at both ends for a tight fit into an air compressor hose.

    Making these sprayers is a specialized craft.  The sprayers come in dozens of different configurations.  The sizes of the container, nozzle, and mouth stem as well as the distances between these parts, all determine the characteristics of the spray pattern.  In general, larger containers are used for larger work (e.g. sculpture), while the smallest containers are used for spraying underglazes and details.

    The parts that make up a glaze canister.

    Some of my locally made glaze spraying canisters

    Comparing spray patterns. On the left, Paasche L Sprayer #4 attached to air-tank compressor, approximately 30-40 psi. On the right, Jingdezhen glaze canister with fish-tank magnetic air compressor.

    The Paasche L Sprayer #4

    The Paasche L Sprayer #4

    Like Jingdezhen glaze canisters, the Paasche allows you to make fine adjustments in distance between the nozzle and container tube.  Along with adjusting air pressure and glaze thickness, a number of different spray patterns can be achieved.

    Spraying

    It’s difficult to write about actually spraying glaze, because each session is different.  The basic process is:

    • Spray outsides.  Do not rest ware directly on turntable or plaster disc, but rather elevate it with a stable item such as a smaller plaster column.  If the inside is already glazed, on top of the support you can add a sponge disk.
    • After spraying the bottom, you can scrape glaze off of the feet.
    • Ideally, wait one day while the bottoms dry completely.  If in a rush, blow air over the ware with a fan.
    • Spray insides.  Take care that feet are not resting on a surface that will become wet during glazing.  The dry plaster turntable disk helps with this issue.
    • Clean glaze off the feet by trimming or with a sponge.

    To spray:

    • Using a notch in the turntable disk as a guide, keep a mental note of how many revolutions you make and the resulting thickness of the glaze (checked by scraping).  The number of revolutions will vary each glaze session, and is influenced by the glaze canister, air pressure, glaze consistency, size of ware, etc.
    • Keep the glaze canister in constant, steady motion- up & down, side to side, or circular.  You may need to vary the motion to get consistent application.

    Using a toilet brush for mixing up the glaze each time I fill the canister

    It's difficult to see in this photo, but the center of this dish was trimmed thin, and the sprayed glaze has saturated the ware. The surface of the glaze is no longer powdery. Stop spraying.

    I've found no consistent way to check glaze depth other than scraping with a knife.

    After spraying the bottom, glaze can be scraped off with a box cutter blade or metal rib. Take care not to scratch the ware.

    After spraying the bottom, a board is placed on the foot, then flipped over and placed on a ware board.

    A large circular piece of foam is used to flip over glazed ware, protecting the insides.

    Ware is placed on a damp, firm foam pad and rotated using even pressure, resulting in a clean glaze line.

    Foam after cleaning a bottom. Foam firmness and hand pressure determines glaze line height.

    Another method for creating a clean glaze line- using a notched rib.

  • Techniques

    Mixing test glazes

    It’s important to wear a NIOSH certified mask whenever using dry glaze materials.

    I guess mixing up glazes isn’t that big of a deal, but I’m sharing my technique just in case there are some absolute beginners out there.

    I find it easier to use a digital scale, see my article here.

     

    Glazes “don’t travel well”, in other words materials, application, and firings vary from studio to studio.  Even for well-known glazes, it’s important to first make a small tests.  For these tests, I use 50g or 100g of material and apply the test glaze to a number of different clay bodies.

    I use the Glazy Batch Calculator on my phone which will show you the subtotals for arbitrary amounts of total glaze materials.

    Once I’m happy with a test, I mix up a larger batch of 1-2Kg.  1Kg is enough material to glaze small cups, 2Kg is a good amount for small bowls.  These larger tests should reveal any problems with glaze suspension (is bentonite required?), application (cracking, peeling, etc.), and fired glaze defects.  Once you have some nice results with 1Kg, you can finally move on to a big bucket of 5-10Kg.

    Mixing up a test

    I use cheap, reusable restaurant soup containers with lids. The size fits my small sieves perfectly, and they are easier to use than plastic cups. Glaze name & recipe is written on container with permanent marker.

    Carefully measure out each ingredient into the bowl, placing into separate piles so that any extra material can be easily removed.

    Dry mix the ingredients with a spoon until well dispersed.

    For 100 grams of material, add about 50ml of water (less if your glaze has little or no clay). I am paranoid and use water from my reverse osmosis filter, as my tap water is hard and sometimes of questionable quality.

    Wait a few minutes until the water has thoroughly soaked the materials, then stir. Glaze should be fairly thick, do not add too much water as you will be adding more as you go along.

    I use a stiff rib to scrape the glaze through the sieve. Do yourself a favor and get containers that perfectly fit your sieves.

    The first pass takes the most work as the clays are broken apart.

    Try not to lose any material, especially if preparing for volumetric blending. Use a water sprayer to clean the container, spoon, and sieve after each pass. But don't add too much water.

    I do two or three passes through the sieve. After the final pass, the glaze should be creamy without any large grains or lumps.

    Now you can slowly mix in a bit of water. I keep the glaze thicker than normal. Flat test tiles require the least amount of glaze.

    Flat test tiles require the least amount of glaze for application.  Here’s my article about how I make test tiles.

    Sieve Mesh Size

    For “natural” glazes containing large-grained materials or ashes, or in cases where homogeneity is not a concern, it’s fine to use a larger screen of 60-80 mesh.  But in all other cases I use 120 mesh or smaller.  Small mesh size is very important for glazes that contain small amounts of very important materials such as coloring oxides (e.g. cobalt and iron).  But it’s also important to ensure that materials are adequately broken up and mixed (such as clays).

    Below you can see two tests of the same batch of glaze fired in the same kiln.  The glaze on the left was applied after passing the materials three times through an 80 mesh screen.  The glaze on the right is the result of passing that same glaze once more through a 120 mesh screen.

    A test celadon glaze. 100g of material passed through an 80 mesh screen 3 times. Note the iron spots.

    Passing the exact same batch of glaze one more time through a 120 mesh screen adequately disperses the glaze materials.

    Poorly dispersed colorants like iron are easy to see in fired glazes.  But keep in mind that other “invisible” glaze ingredients like clays, feldspar, etc. also need to be well-dispersed and mixed in order to ensure the glaze melts properly.  If you use a 60-mesh screen for tests and then a 120-mesh screen for large glaze batches, there will be differences between the fired results.

  • Glazes

    Seeing the cones

    I’ve seen a few techniques for seeing into the kiln at high temperature.  An old friend of mine still prefers blowing into the peephole, unfortunately on more than one occasion it has resulted in the particles resting in the peephole to be blown in as well, settling on the ware.  The Jingdezhen firing masters I’ve met just put on an old pair of sunglasses and squint (on the rare occasions they actually need to look at a cone).

    I’m currently using #5 welding goggles, the only pair I could find for sale here but they work really well.  If you have a choice, go for IR rated lenses which protect from harmful infrared light.  Here’s a really good article about eyeware for potters.

    Combined with the goggles, a strong flashlight will give you a really good view inside the kiln.  This year, my old LED flashlight finally gave out, and at around 400 lumens it was still a little difficult to see in the kiln.  The LED flashlight I purchased as a replacement was on sale for about $40USD, a little expensive but to be honest I just wanted to know what 2000 lumens would look like.  It’s blinding!  But using this flashlight I can see all the way to the back of the kiln even in reduction at 1300° C (my kiln is only 1 meter long).  You can even see glazes start to glisten in the light of the flashlight as they begin to melt..

    So if you’re getting a new flashlight for the kiln, I think you should go for at least 1000 lumens.

    Welding goggles and the flashlight

  • Glazes

    Qing Dynasty Test Tiles

    Spotted in a friend's book. Unfortunately I forgot to record the title.

  • Glazes

    Glazy open source ceramics recipe library

    I invite all of you to join Glazy, a ceramics recipe library that allows anyone to browse and add pottery recipes for free.

    Glazy was built using the latest open source tools, including Laravel and Bootstrap.  The database of ceramic recipes was originally seeded with data from Linda Arbuckle’s GlazeChem database and John Sankey’s glaze database. John Britt, Alisa Liskin Clausen, Terry Rorison and Tara Hagen have also included their glaze tests with images.

    Since it’s release, many new features have been added to Glazy, including improved charts and color search.  More information can be found on the Glazy help page.

    If you have ceramics recipes that you would like to add, or if you would like to help organize the recipes already in the database, please contact us.

    Glazy is constantly improving and evolving.  I hope you will join us!

  • Glazes

    Glazy: Glaze recipes most used materials

    With the data stored in Glazy it is possible to visualize recipes using graphs and charts.

    In the future, these visualizations and more will be added to Glazy at http://glazy.org/graphs

    Below are simple pie charts showing the most commonly used glaze materials for both Mid-Fire and High-Fire glazes.

    For those who are just starting out with glazes, these charts could be a useful guide when stocking glaze materials.

    The charts on the left are for “base” materials, the materials that form the actual glaze.  On the right are charted the “additional” materials- typically colorants and opacifiers- that are added to the base glaze materials.

    There are still some strange and untrustworthy recipes in the Glazy database that may have skewed the results somewhat.

    Below are the charts for High-Fire glazes.

  • Glazes

    Orton Cone 10 Reduction Glaze Line Blends

    Leach 4321 is a simple, reliable glaze that we can use to compare coloring oxides.

    All of the following glaze variations can be found on Glazy:  http://glazy.org/search?search_words=leach&category=36&cone=high

  • Jingdezhen

    Yaoli Village and Raonan Outdoor Ceramics Museum

    Yaoli Ancient Village (瑶里古镇) is a fairly well-known tourist destination located about 1 1/2 hours by car from Jingdezhen.

    During the past few years I have visited the village a handful of times, and each time I’m even more disappointed by the continuous development, poor management, and flocks of tourists.

    But the countryside around Yaoli is beautiful.  If you continue driving past the ancient village you will find numerous small villages with restaurants offering local cuisine.  Drive up the mountain and you should come across wonderful views of the valleys as well as waterfalls.

    A village near Yaoli

    An ancient bridge in the countryside

    One of the waterfalls to be found in the mountains

     

    Yaoli is also the home of a type of porcelain stone known as “glaze stone”.  This stone is a major component of traditional Jingdezhen glazes.

    There is a very nice outdoor museum in Yaoli called Raonan (绕南陶瓷主题园区) which runs along a small river.  The river powers hammer mills that continuously crush Yaoli porcelain stone.  There are also ancient dragon kilns and even pottery wheels where you can try throwing Jingdezhen porcelain.

    The river running through the ceramics museum

    A water wheel powers large hammer mills

    The hammer mills crush porcelain stone

    The crushed stone powder is washed, mixed, and dried in large pits.

    The porcelain paste is formed into bricks and air-dried.

    One of the remaining dragon kiln ruins. Chambers can be seen at the bottom of the kiln.

    Another dragon kiln at the Yaoli site.

    Large piles of waste saggars and shards surround the kiln sites.

  • Glazes

    Digital Scales for Weighing Glazes

    After years of using simple balance scales to measure out glazes, I finally decided to invest in a better setup. I couldn’t find any triple-beam scales for sale in Jingdezhen, so instead I purchased a cheap 200-gram digital scale from a local shop.  I was delighted at how much simpler and faster it was to mix up tests with the digital scale.  It was only a few months later when I compared the digital scale to my old balance scales and discovered that the digital scale was consistently inaccurate, even just after calibration.

    After having wasted 600RMB, I decided to just buy the best reasonably priced scales I could find.  The only imported brand in my price range and available in China was the Ohaus Scout Pro line.  I purchased two- one for tests and measuring colorants (model SP202, up to 200 grams with 0.01 gram readability) and one for mixing up bigger batches of glaze (model SP4001, up to 4000 grams with 0.1 gram readability).

    The SP202 is very accurate, great for when you are making very small test batches.  The scale can also be used to measure colorants for big batches of glaze.

    I use the SP4001 to directly measure out 1-3kg batches of glaze, or for measuring out each ingredient in larger glaze batches.

    After a couple years, the Ohaus scales are still performing very well, especially considering that they are stored on the glazing patio and subjected to the weather.  The scales cost me much more than I wanted to spend, but they are well worth the money.

    In conclusion:

    • If you’re looking to purchase scales for small glaze batches but don’t have a lot of money to spend, go for a triple-beam scale.  A good triple-beam will be much more trustworthy than a cheap digital scale.
    • If you only have enough money to buy one digital scale, get a 200-gram scale, preferably with .01 readability.  This will allow you to make accurate test glazes, as well as accurate colorant additions to larger batches of glazes.
    • If you do buy a digital scale, don’t forget you will need to calibrate it from time to time.  (I do so each glaze-making session.)  You will need accurate calibration weights in order to so, adding to the final cost.