A pure terra cotta (red burning) clay that we dig straight out of the ground and grind into a powder. It is highly plastic and very smooth (fine particled). Its plasticity and dry hardness make it suitable in earth-mortars, green construction, pastes that need to be sticky and slurries that need to suspend well.

98Mix lumps on stockpile


This clay has a low melting point. This makes it suitable as a fire-bonding-agent or as an addition to bodies to reduce their vitrification temperature.

Fired bars. Top to bottom: Cone 4, 2, 02, 04, 06.

Mixing Instructions

If you are using this is in a non-ceramic application you likely are interested in the plasticity (its stickiness in the wet state, the way it can be shaped, the way it can bond things together, its ability to dry hard). Remember, this is still a clay, if subjected to water after it dries it will become sticky and pliable again (unless you add a hardener). Clays vary widely in grain size and shape and total particle surface area, plasticity (ability to form a shape), stickiness, drying hardness, drying speed and drying shrinkage. The most plastic clays are the stickiest, shrink and crack the most and dry the slowest. 98 Mix is among the most plastic clays available, and it shrinks 7%+ from the plastic form to dry form. That means you need to blend it with sand (and possibly fibrous material, like straw) to reduce the shrinkage (and therefore the cracking). But, the more sand the more the reduction in plasticity, stickiness and dry hardness. Experimentation will be required to determine the mix that imparts the best compromise between strength and low drying shrinkage.

As noted, if exposed to the rain, this clay will wash away (although much slower than dirt or other clays). It is possible to incorporate a hardener in your mix to give it more resistance the water slaking. Building supply stores have products suitable for this.

Physical Properties

 Drying Shrinkage: 8.0-9.0%

Sieve Analysis (Tyler mesh):

     +48: trace
   48-65: 0.1-0.5
  65-100: 0.5-1.5
 100-150: 2.0-4.0
 150-200: 6.0-8.0

Fired Shrinkage:

 Cone 06: 1.0-2.0%
 Cone 04: 3.0-4.0
 Cone 02: 6.0-7.0
  Cone 2: 7.0-8.0

Fired Absorption:

 Cone 06: 10-12%
 Cone 04: 5.0-8.0%
 Cone 02: 0.5-1.5
  Cone 2: 0.0-0.5

Safety Data Sheet

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Logo Plainsman Clays Ltd.
702 Wood Street, Medicine Hat, Alberta T1A 1E9
Phone: 403-527-8535 FAX:403-527-7508