Using a Sodium Silicate Pottery Technique to Create Cracked Texture

Creating Texture is Easy with this Sodium Silicate Pottery Technique

Sodium Silicate on Pottery

Sometimes I feel like I was born in the wrong era because I just love old things: antiques, weathered old buildings, vintage clothing. If you can relate, then you’ll love today’s feature because we’re going to show you how to create a crackled, craggy texture on your pottery using a sodium silicate pottery technique.

The late Canadian potter, Robin Hopper, explains how some heating, some stretching and a little sodium silicate on pottery can transform a freshly thrown pot into what looks like a weathered antique. –Jennifer Poellot Harnetty, editor.

PS: For more information on creating cracked texture on your pottery, check out this post on intentionally creating glaze defects.


Interested in pottery surfaces? Try this sodium silicate pottery technique!

Brushing the surface of a thrown pot with sodium silicate, quick-drying the surface with a heat gun or blowtorch until the surface no longer is tacky, then expanding the form from inside can give a piece of pottery an aura of instant antiquity.

The sodium silicate is a thick liquid salt solution that forms a thin skin that, with applied heat, quickly hardens on the surface, encasing the soft and therefore, still malleable, clay cylinder beneath. Normally used as a deflocculant for casting slips, in this use it is quickly dried to the touch with some heat from a blowtorch. At this point, it is like a candy apple, crunchy on the outside and soft inside.

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Throw a soft clay cylinder, clean the surface of residual slip, and impress with various tools.

Paint the surface of the cylinder with a sodium silicate solution.

When the form is then expanded with pressure from inside, the skin surface cracks enlarge in size depending on the amount of pressure and expansion. In this sodium silicate pottery technique, the residual sodium silicate gives a slightly glazed surface like a thin salt glaze.

Variants that will also work are a thick salt (sodium chloride) solution or sugar pancake syrup (Aunt Jemima’s, for example) solution (which produces great caramel smells from the caramelizing sugar during the firing!). The essence of the process is in the speed with which it is done, as the coating needs to stay hard and not absorb moisture from the soft clay beneath.

Expand the soft, decorated form on the wheel from the inside, while drying with a heat gun on the outside.

This detail shows the decorative cracking created from heating and expanding the sodium-silicate-coated clay.

Make your mark!

Robin Hopper's Making Marks covers everything you need to know about enriching the ceramic surface. From concepts and ideas to research and processes, his book shows you the great variety of marks you can make at any stage of the ceramic process. Whether you want to carve or add clay, brush on slips or dip glazes, raku or pit fire—you'll discover how to choose and use the technique you need for your pots!

Book: $49.97 | PDF: $39.97

Learn more!

The late Robin Hopper and his wife Judi Dyelle owned and operated Chosin Pottery in Victoria, British Columbia, Canada. Visit www.chosinpottery.ca to see images of their work and learn more about Chosin Pottery.


**First published in 2009
Comments
  • Merrilee M.

    I love the look of this, but do hand building only. I’ve seen it done on hand build pieces but am not sure how to go about it. I’d love it if someone would share that.

  • Brigitta F.

    It is one of my favorite things to do, to make crackle pots. I have been practicing it for about 1 year and instead of a heat gun, I use a gas torch and come up with pretty interesting results. Glad to see other potters are also interesting in the Sodium Silicate process and are making various crackle pots.

  • Hello,

    Today’s my first day on Ceramic Arts Daily, and I seem to have come home right here!

    I’ve been using sodium silicate for about a year. This year’s “crop” was stoneware with ochre from Continental Clay in Minneapolis – a dark, dark cone 10 body.

    I throw a very thick cylinder. Remove slip, dry with heat gun. Three coats of one or several slips, each one dried. Then sodium silicate, dried. (I guess there’s not a way to show photos here, but one would be worth a thousand words, of course.) Because of all the drying, the clay itself cracks and opens up, as well as crackling between. I also put spiral needle lines on the cylinder, sometimes planned with colors, and they open up to show the stretched clay very nicely. Expanding the clay with one hand is great fun and the best surprises come when you stop the wheel, ’cause you cannot see what’s happening while you’re doing it. I’ve made primarily round-bellied vase shapes.

    I have a background in archaeology – these pots are so fulfilling in their simplicity, use of clay that only clay could do, showing the “clayness”, spontaneity. No glaze outside over the slips, though I did try a clear glaze over a white slip which worked for me. I prefer a “natural” or even clay-colored glaze inside, to not detract from the textured matte exterior. I’ve successfully (for what I was after) used a white, tangerine, jade, seafoam and a variety of colored slips – a dry, “old” look.
    Jan

  • Hi all. Does anyone know about the firing of a finished piece? Is the bisque firing at a cone 06? the glaze at a cone 5/6? Or is this more of a low firing type of clay body? Any info would be greatly appreciated!!

  • I’ve used this method with a sodium silicate mixed with a white slip on a dark clay body with great results. The greater the proportions of sodium silicate to slip, the larger the “cracks”. By running my fingers through the silicate slip layer when partially dry, I create areas of varing cracking textures. Each piece turns out a little different depending on how long you let the slip dry. Sometimes I expand the piece a little when the slip is partially set, continue to dry and then expand to the final shape to create a pattern within a pattern. I do not glaze the textured area but let the dark/white texture contrast of the two clay bodies stand on it’s own.

  • I’m going to try this on my burnished pots, feel quite excited – its going to work…. I’m sure, not hope…thanks…..

  • I made 3 of these today. I will trim the feet of them and then post some videos on youtube tomorrow., look for markspottery and you will find my vids. I used slip and iron oxide with the sodium silicate . Did not get great big cracking, will try for bigger cracks tomorrow. It is a fun process

  • This is quite insightful. i`m delighted by this approach. I`ve been experimenting on surface decoration lately and this is very helpful.

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