Archive for March, 2017

  • Antiques

    Nothing new under the sun..

    With 10,000 years of history, there’s really never anything new in ceramics, just reinterpretations of the past.  Bowl base fragmentEdo period, Takeo Karatsu type.  Freer & Sackler Galleries.

  • Traditional

    Traditional celadon

    Recent firing with traditional porcelain stone glaze.  In the past I’ve tried but failed to use modern materials like feldspar and kaolin to capture the beautiful, unctuous surface and depth of porcelain stone celadons.  In this glaze the coloration is completely due to iron occurring naturally in the material.

  • Techniques

    Blades

    I use X-acto blades all the time, some modified for specific tasks like carving porcelain or scraping glaze off of feet.

    I’m not sure if it’s all part of a vast X-acto conspiracy, but it seems that a lot of people don’t know that these blades can be easily & quickly sharpened?  While there are a number of sharpening methods (even just using bare fired porcelain) that will work, it can be tedious to get the sharpening angle right.  The most convenient method I have found is an angled sharpener (pictured).  Just a few quick passes through the ceramic sharpener gets the blades useable again.  It’s faster for me to sharpen the blade than switch out a dull blade for a new one.  (Unfortunately my sharpener is approximately 45% degree sharpening angle (> 20 degrees per side), it might be better to have a narrower-angled sharpener.)

    Also note that not all X-acto blades are stainless steel.  You don’t want rusty blades all over your studio or in your reclaim.  A 10 or 100-pack of stainless steel #11 blades might last you a lifetime.

     

    A step up from the X-acto blades are stainless steel surgical blades.  They come in a wide variety of shapes and sixes perfect for a number of jobs.  I usually use the blades without a handle.  They come in ten-packs and last a really long time if you sharpen them.

  • Techniques

    Pouring Glaze with a Watering Can

    I’m sure that using a garden watering can for pouring glazes is a common technique, but when I came up with the idea I thought I was a genius 🙂  The design of a watering can ensures a constant, strong stream of liquid during pouring that is perfect for glazing.  Bubbles are reduced since the watering can pours liquid from the bottom of the can.

    Adjust the specific gravity of the glaze. Here, a 250ml beaker is zeroed-out.

    The weight of 250ml glaze is 386.7. Dividing by the weight of water, 386.7/250 = 1.55. For this glaze, 1.5-1.6 is a good pouring thickness.

    Filling a watering can with glaze.

    Rotating the piece with your hand, maintain a continuous pour of glaze.

    You might need to rotate the piece backwards and forwards two or three times.

    Using a brush with watered-down glaze, fill in any holes.

    Glaze must be sufficiently watery in order to be absorbed into the hole.

    Glaze will inevitably end up on the outside of the piece. First scrape with a blade or metal rib.

    Finally, sponge off any glaze that remains on the outside.

    Pouring the Outside

    Once the inside is glazed, I will wait until the next day to glaze the outsides.  It’s important not to overload the bisque ware with water.

    I use an old electric wheel for pouring the outsides.  It’s important to rotate the wheel at sufficient speed so that glaze does not gather on the inside rim of the pot.

    Here’s a good video by John Britt about pouring the outsides on a turntable.

    Plastic strips are inserted into the splash pan to prevent glaze from spraying outwards. A heavy plaster model is tap-centered on the wheel.

    A soft piece of sponge is placed on top of the plaster to protect the inner glaze surface.

    A bowl is placed on top of the plaster model and tap-centered.

    The watering can is used to pour glaze starting from the foot. My finger stabilizes and prevents glaze from running into the foot.

    The application properties of your glaze will determine the amount of time the glaze should be poured. For this celadon glaze with an SG of 1.48 I pour from 4-5 seconds. Keep the wheel turning after glazing to ensure excess glaze is forced from the rim.

    Once the glaze has lost its glossy sheen, scrape off glaze from the bottom of the foot with a rib.

    Using a wet, clean sponge, clean off remaining glaze from foot.

    With sufficient wheel speed, the glaze should not gather too much on the inside of the pot. Once dry, excess rim glaze can be scraped off.