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L210

Description

Low temperature, silty smooth, medium plastic, brown-burning, native terra cotta body. L210 is a low-talc low-fire terra cotta body that Plainsman has made for many years. Its main appeal has been to schools that like its light raw color since this is easier to clean up. L210 burns browner than our other low temperature reds. Because it is low in talc L210 may craze with some commercial glazes (however making your own glaze is easy and much less expensive).

Process Properties

L210 is a mix of one of our low fire red-burning fine grained plastic materials with a silty buff stoneware clay and 10% talc. It has medium plasticity and very slight texture. It is somewhat susceptible to water splitting so we recommend care not to use excessive water in pulling handles and throwing extreme shapes. Where joins with slip are made (i.e. handles), wipe away any excess that gets squeezed out during compression to avoid a split.

We do not recommend L210 for large sculptural ware since it lacks coarser particles and has a fairly high drying shrinkage. To avoid drying cracks use our recommended drying procedures. The most important of these is do what is necessary to make drying even throughout the piece. You can do this using a damp room or covering with a cloth and then plastic to slow down drying (the slow down helps even it out).

Firing

L210 fires to a light brown at cone 04-06. By cone 02 the color dramatically intensifies to a dense stoneware brown. By cone 4 it is over fired.

L210's warm color and strength in the cone 1-3 range make it a good candidate to produce low fire stoneware or vitreous tile. However be careful of warping if shapes are overhung too much.

Like any other low-fire body at cone 06-04, L210 is fairly weak and has high porosity. You might consider bisque firing higher (e.g. cone 03) to strengthen ware if you need to fire at 06-04 for your glaze. Please experiment since the increased density associated with higher bisquing can make it difficult to get the glaze to adhere and dry. Remember that L210 suddenly becomes very dense between 03 and 02 so your bisque firings need to be precise in this range.

L210 fired bars. Cone 06, 04, 02, 2 and 4 (bottom to top).

Glazing

Many find that commercial brushing and dipping glazes dry very slowly and drip badly. And they often do not fit well (craze or shiver). And they are expensive. With a little effort you can make your own of both types. And add stain and opacifier powders to make almost any color. There is no need to search for a recipe, we have done it for you. You can mix your own glaze from a pre-mixed powder you buy from us or weigh out your own ingredients. However, at low temperature, there is no one-glaze-that-fits-all bodies. To solve this we have created a three-recipe solution, these have thermal expansions that span the entire range of low fire bodies. And they fire crystal clear (in a drop-and-hold firing). Our Zero3 K transparent glaze fits low talc bodies (like L215) and low fire stoneware (like Zero3), Zero3 H fits high talc bodies (like L213, L212) and Zero3 L fits zero talc bodies (like Terrastone and Buffstone). We recommend cone 04-03 using a drop-and-hold firing schedule (for defect free surface and good transparency). Do not trust electronic controllers to be accurate, we verify using cones and manually program to compensate for error. If you need to fire lower or higher than 03, be sure and do testing first.

Blending the K, H and L glazes is encouraged to get the best fit. We recommend stress testing by boiling-water-into-ice-water (and vice versa) to bring out any crazing or shivering. If crazing occurs, blend in some of the L. If shivering occurs, blend in some of the H. In this way these glazes can be optimally fitted to almost any clay body.

It is also practical to make your own brushing glazes, ones that will work identically to the commercial ones mentioned above. Like the dipping versions, you can blend to tune the thermal expansion to fit your clay body. Click here for more information on how to do this. You will be surprised at how easy it is and how much money you can save.

L210 is also a candidate for use with cone 2 or 3 stoneware glazes. Keep in mind that transparent glazes may tend to darken the color of the clay more than you expect. For cone 2, increase the kaolin in the glaze to 30%. If the glaze is still melting too much add silica in 5% increments until it is right.

L210 has some coarser particles and thus can pinhole certain glazes. However by soaking the kiln (holding the temperature at top) these problems can be solved.

Thermal Expansion

This chart is for the old mix of L210 and was derived from a specimen fired once to cone 04 in the Plainsman lab and tested in an Orton dilatometer (note the quartz inversion hump). We have not tested the new mix yet but it likely has a higher thermal expansion since it contains 10% talc. If you fire to a different temperature, employ different heatup or cooldown rates, or glaze-fire more than once the thermal expansion in your ware may be different than this chart indicates.

Thermal Expansion Chart. Average: 6.4.

Physical Properties

 Drying Shrinkage: 6.0-7.0%
 Dry Strength: n/a
 Water Content: 22.0-23.0%
 Drying Factor: C130
 Dry Density: n/a

Sieve Analysis (Tyler mesh):

     +35: 0.0-0.2%
   35-48: 0.5-1.0
   48-65: 0.5-1.0
  65-100: 1.0-3.0
 100-150: 2.0-4.0
 150-200: 5.0-8.0
 200-325: 10.0-13.0

Fired Shrinkage:

 Cone 06: 1.0-2.0%
 Cone 04: 2.0-3.0
 Cone 02: 6.0-7.0
  Cone 2: 7.0-8.0

Fired Absorption:

 Cone 06: 10-12%
 Cone 04: 8.0-10.0%
 Cone 02: 2.5-3.5
  Cone 2: 0.5-1.5

Safety Data Sheet

Click here for web view.

We Are Rationalizing Our Product Line

Plainsman manufactures bodies by grinding and pugging clays that we mine (native bodies) and by batch mixing bagged minerals and materials that we import (refined bodies). We stock about 10,000 boxes of 50+ clays (some in multiple stiffnesses) and need to reduce the warehousing and production burden of small-run bodies and remove obsolete and legacy products. For bodies being discontinued: We have migration paths and can assist with issues. Some changes involve increased cost. In certain cases you might consider having us custom-mix a body so you can continue to get it, but please work with us on trying to adapt to alternatives first.

This product has issues

  • A legacy body recipe that predates newer and better materials.
Logo Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508
Email: plainsman@telus.net