325 mesh | 3D Design | 3D Printer | 3D Slicer | 3D-Printed Clay | 3D-Printing | Abrasion Ceramics | Acidic Oxides | Agglomeration | Alkali | Alkaline Earths | Amorphous | Apparent porosity | Ball milling | Bamboo Glaze | Base Glaze | Base-Coat Dipping Glaze | Basic Oxides | Batch Recipe | Bisque | Bit Image | Black Coring | Bleeding colors | Blisters | Bloating | Blunging | Bone China | Borate | Boron Blue | Boron Frit | Borosilicate | Breaking Glaze | Brushing Glaze | Calcination | Calculated Thermal Expansion | Candling | Carbon Burnout | Carbon trap glazes | CAS Numbers | Casting-Jiggering | Celadon Glaze | Ceramic | Ceramic Binder | Ceramic Decals | Ceramic Glaze | Ceramic Ink | Ceramic Material | Ceramic Oxide | Ceramic Slip | Ceramic Stain | Ceramic Tile | Ceramics | Characterization | Chemical Analysis | Chromaticity | Clay | Clay body | Clay Body Porosity | Clay for Ovens and Heaters | Clay Stiffness | Co-efficient of Thermal Expansion | Code Numbering | Coil pottery | Colloid | Colorant | Cone | Cone 1 | Cone 6 | Cone plaque | Copper Red | Cordierite Ceramics | Crackle glaze | Crawling | Crazing | Cristobalite | Cristobalite Inversion | Crucible | Crystalline glazes | Crystallization | Cuerda Seca | Cutlery Marking | De-Airing Pugmill | Decomposition | Deflocculation | Deoxylidration | Digitalfire Foresight | Digitalfire Insight | Digitalfire Reference Library | Dimpled glaze | Dip Glazing | Dipping Glaze | Dishwasher Safe | Dolomite Matte | Drop-and-Soak Firing | Drying Crack | Drying Performance | Drying Shrinkage | Dunting | Dust Pressing | Earthenware | Efflorescence | Encapsulated Stains | Engobe | Eutectic | Fast Fire Glazes | Fat Glaze | Feldspar Glazes | Firebrick | Fireclay | Fired Strength | Firing Schedule | Firing Shrinkage | Flameware | Flashing | Flocculation | Fluid Melt Glazes | Flux | Food Safe | Foot Ring | Forming Method | Formula Ratios | Formula Weight | Frit | Fritware | Functional | GHS Safety Data Sheets | Glass vs. Crystalline | Glass-Ceramic Glazes | Glaze Bubbles | Glaze Chemistry | Glaze Compression | Glaze Durability | Glaze fit | Glaze Gelling | Glaze Layering | Glaze Mixing | Glaze Recipes | Glaze Shrinkage | Glaze thickness | Globally Harmonized Data Sheets | Glossy Glaze | Green Strength | Grog | Gunmetal glaze | Handles | High Temperature Glaze | Hot Pressing | Incised decoration | Industrial clay body | Ink Jet Printing | Inside-only Glazing | Insight-Live | Interface | Iron Red Glaze | Jasper Ware | Jiggering | Kaki | Kiln Controller | Kiln Firing | Kiln fumes | Kiln venting system | Kiln Wash | Kovar Metal | Laminations | Leaching | Lead in Ceramic Glazes | Leather hard | Lime Popping | Limit Formula | Limit Recipe | Liner Glaze | LOI | Low Temperature Glaze Recipes | Lustre Colors | Majolica | Marbling | Material Substitution | Matte Glaze | Maturity | Maximum Density | MDT | Mechanism | Medalta Potteries | Medium Temperature Glaze | Melt Fluidity | Melting Temperature | Metal Oxides | Metallic Glazes | Micro Organisms | Microwave Safe | Mineralogy | Mocha glazes | Mohs Hardness | Mole% | Monocottura | Mosaic Tile | Mottled | Mullite Crystals | Native Clay | Non Oxide Ceramics | Oil-spot glaze | Once fire glazing | Opacifier | Opacity | Ovenware | Overglaze | Oxidation Firing | Oxide Formula | Oxide Interaction | Oxide System | Particle orientation | Particle Size Distribution | Particle Sizes | PCE | | Phase change | Phase Diagram | Phase Separation | Physical Testing | Pinholing | Plainsman Clays | Plaster Bat | Plaster table | Plasticine | Plasticity | Plucking | Porcelain | Porcelaineous Stoneware | Pour Glazing | Precipitation | Primary Clay | Primitive Firing | Production Setup | Propane | Propeller Mixer | Pyroceramics | Quartz Inversion | Raku | Reactive Glazes | Reduction Firing | Reduction Speckle | Refiring Ceramics | Refractory | Refractory Ceramic Coatings | Representative Sample | Respirable Crystalline Silica | Restaurant Ware | Rheology | Rutile Glaze | Salt firing | Sanitary ware | Sculpture | Secondary Clay | Shino Glazes | Shivering | Sieve | Silica:Alumina Ratio | Silk screen printing | Sintering | Slaking | Slip Casting | Slip Trailing | Soaking | Soluble colors | Soluble Salts | Specific gravity | Splitting | Spray Glazing | Stain Medium | Stoneware | Stull Chart | Sulfate Scum | Sulfates | Surface Area | Surface Tension | Suspension | Tapper Clay | Tenmoku | Terra cotta | Terra Sigilatta | Test Kiln | Theoretical Material | Thermal Conductivity | Thermal shock | Thermocouple | Thixotropy | Tony Hansen | Toxicity | Trafficking | Tranlucency | Translucency | Transparent Glazes | Triaxial Glaze Blending | Ultimate Particles | Underglaze | Unity Formula | Upwork | Viscosity | Vitreous | Vitrification | Volatiles | Warping | Water in Ceramics | Water Smoking | Water Solubility | Wedging | Whiteware | Wood Ash Glaze | Wood Firing | Zero3 | Zeta Potential

Permeability

In ceramics, the permeability of clay slurries and plastics determines the rate as which water can move through the matrix

Details

The term "permeability" can occur in multiple contexts in ceramics. Most often it refers to how well water can penetrate a clay (either in its dried solid form, or as a powder). Bentonites, which can have incredibly high surface areas, are among the least permeable clays. And they take the longest to dry. Bentonite powders, if wetted for example, can form a thin gel layer only millimeters thick, that blocks the passage of any more water. Koalins, which have large particles and can be quite non-plastic, are very permeable to water. And they dry quickly. Some non-clay minerals can also exhibit resistance to the penetration of water.

Interestingly, clays that have already been brought to the wet, plastic form, are quite impermeable. But when dried out completely, they will slake rapidly in water.

Ceramic slurries with high permeability cast quickly. Knowing how quickly is important in manufacture. Slurries with more fine clay particles are less permeable (but also more plastic and of higher dry strength). Testing equipment measures it as Bariod Permeability. This is done in a small pressure vessel with a filter membrane and outlet. After pressurizing for a set time the slip is drained and the filter clay examined (weighed, thickness measured).

Related Information

Permeability demonstration of Texas and Montana talcs

Texas talc (left) quickly absorbs all the water poured on it. Montana talc (right) resists whetting of the particles much more, the water is just sitting on top and has not penetrated at all.

A stock pile of raw, unground ball clay

Plainsman A2. In spite of three times the normal rain fall this summer, its natural high impermeability made it shed almost all of the water. But there is a back story. When mined this clay was quite wet, about 10% moisture - some of the lumps were 100 lbs! The outer ones dried over a period of weeks and, in the process, fractured down to the inch-size you see here. But the inner section of the pile took years to dry out. By now it has broken down so fine that a completely dry sample put into water will slake in minutes to produce a smooth slurry.

Links

Materials Ball Clay
Materials Kaolin
Materials Bentonite

By Tony Hansen

Monthly Tech-Tip from Tony Hansen

Sign up at the home page.


Tell Us How to Improve This Page

Or ask a question and we will alter this page to better answer it.

Email Address

Name

Subject

Message


Upload picture

Please check recaptcha to proceed



https://digitalfire.com, All Rights Reserved
Privacy Policy