CLWC - Clay Water Content - Powder, Plastic Test

Variables

WPOW - Water Content Powder (V)

This figure is measured, calculated, and supplied by production. It is expressed as a percent of the damp weight, and is calculated by weighing a wet sample, drying at +100 degrees C, weighing again, and calculating the percent loss in weight.

Production gets a sample of clay from infront of the hammer mill. Approxiamatly 3-5 grams. They pre-weigh it, and place under the heat lamps about 2 1/2 inches away, for about 20-30 minutes.

POWW - Powder Wet Weight (V)

POWD - Powder Dry Weight (V)

WPUG - Water Content Pugged (V)

This figure is measured, calculat

PUGW - Pugged Wet Weight (V)

PUGD - Pugged Dry Weight (V)

Procedure

1. Purpose

Typical bodies of modeling stiffness, depending on the type, will have a water content of between 19.5 and 22.5%. The difference between soft and stiff clay is usually less than 1%. However, water content is not an accurate measure of stiffness. Solubles present in the clay, or variations in the electrolyte in the water supply can cause floccing or defloccing of the pugged clay, so that from one run to the next, identical stiffnesses can have quite different water content figures. For this reason it is wise to only use the water content figure as a guide within each clay run.

5. Procedure

Prepare the sample by slicing off a thin section of clay from a slug. Place it on a small flat tray, weigh it and dry it under a heat lamp. Enter the weight in the computer.

Details:

-The small tray can be cut from galvanized metal. It should be slightly bigger than the sample and turned up at one end to allow handling.

-Cut the specimen from the top of a slug of clay using a tight wire to make the vertical and horizontal cuts. Avoid creating 'burrs' that could fall off during handling when weighing the dry specimen.

-The specimen should be about 50mm x 40mm x 3mm thick (wet weight around 10-12 grams).

-Do not handle the sample any more than necessary.

-Place it under a heat lamp apprroximately 2 1/2 " away for about 45 - 60 minutes.

-At no time should the specimen be put on any absorbent surface (i.e. wood, paper, cardboard) or it will lose water.

-A scale capable of .01 g accuracy is necessary. When weighing either counterbalance the weight of the tray first, or subtract its weight from any weighs measured.

Prepare the sample by slicing off a thin section of clay from a slug. Place it on a small flat tray, weigh it and dry it under a heat lamp. Enter the weight in the computer.

Related Information

Links

Tests	Water of Plasticity A physical data value quoted for plastic materials (clays) used in ceramics to indicate the degree to which they will add plasticity to a body.
Tests	LOI/Density/Water Content LDW LOI, density and water content test procedure for plastic clay bodies and porcelains
Tests	Drying Factor/Water Content/Solubles
Tests	Moisture Content - Powder
Typecodes	Body Tests Tests conducted on bodies made from materials, as opposed to the materials themselves.

By Tony Hansen
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