Monthly Tech-Tip from Tony Hansen SignUp

No tracking! No ads! That's why this page loads quickly!

200 mesh | 325 mesh | 3D Design | 3D Printer | 3D Slicer | 3D-Printed Clay | 3D-Printing | Abrasion Ceramics | Acidic Oxides | Agglomeration | Alkali | Alkaline Earths | Amorphous | Apparent porosity | Artware | Ball milling | Bamboo Glaze | Base Glaze | Base-Coat Dipping Glaze | Basic Oxides | Batch Recipe | Bisque | Bit Image | Black Coring | Bleeding colors | Blender Mixing | Blisters | Bloating | Blunging | Bone China | Borate | Boron Blue | Boron Frit | Borosilicate | Breaking Glaze | Brick Making | 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 Glaze Defects | Ceramic Ink | | 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 1 | Cone 5 | Cone 6 | Cone plaque | Copper Red | Cordierite Ceramics | Crackle glaze | Crawling | Crazing | Cristobalite | Cristobalite Inversion | Crucible | Crystalline glazes | Crystallization | Cuerda Seca | Cutlery Marking | Decomposition | Deflocculation | Deoxylidration | Differential thermal analysis | 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 Stain | Engobe | Eutectic | Fast Fire Glazes | Fat Glaze | Feldspar Glazes | Fining Agent | 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 laydown | 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 | Liner glazing | Liquid Bright Colors | LOI | Low Temperature Glaze | Majolica | Marbling | Material Substitution | Matte Glaze | Maturity | Maximum Density | MDT | Mechanism | Medium Temperature Glaze | Melt Fluidity | Melting Temperature | Metal Oxides | Metallic Glazes | Micro Organisms | Microwave Safe | Mineral phase | 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 | Permeability | Phase Diagram | Phase Separation | Physical Testing | Pinholing | Plainsman Clays | Plaster Bat | Plaster table | Plasticine | Plasticity | Plucking | Porcelain | Porcelaineous Stoneware | Pour Glazing | Powder Processing | Precipitation | Primary Clay | Primitive Firing | Propane | Propeller Mixer | Pugmill | Pyroceramics | Pyrometric Cone | 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 | Sieve Shaker | Silica:Alumina Ratio | Silk screen printing | Sintering | Slaking | Slip Casting | Slip Trailing | Slipware | Slurry | Slurry Processing | Slurry Up | 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 | Throwing | Tony Hansen | Toxicity | Trafficking | Translucency | Transparent Glazes | Triaxial Glaze Blending | Ultimate Particles | Underglaze | Unity Formula | Upwork | Variegation | Viscosity | Vitreous | Vitrification | Volatiles | Warping | Water in Ceramics | Water Smoking | Water Solubility | Wedging | Whiteware | Wood Ash Glaze | Wood Firing | Zero3 | Zero4 | Zeta Potential

Ceramic Material

Ceramic materials are employed in the ceramic industry to make glazes, bodies, engobes and refractories. We study them at the mineral, chemical and physical levels.

Key phrases linking here: ceramic material - Learn more

Details

Ceramic materials are employed in the ceramic industry to make glazes, stonewares, earthenwares, porcelains, engobes, refractories, structural products, etc. We study ceramic materials at the mineral, chemical and physical levels.

At first it might seem strange to define this, but it is not as obvious as it seems. In ceramics the concept of a material is different for different people. To a purchasing agent it is a commodity. To a geologist it is a mineral or mix of minerals. To someone most concerned with the physical presence, ceramic materials are an inorganic, non-metallic solid. To a mining crew materials present various challenges in extraction, transport, initial crushing and stockpiling. To a processing department they present sets of issues to grind, separate, purify, size and package. To a production department they are powders that make up part of the recipe of a glaze or body and have associated issues and benefits in process equipment. To a lab technician materials have a physical presence that can be tested and the results of these tests can be expressed on a data sheet. Labs can also deduce the chemistry of a material. To a glaze chemist, materials are "warehouses" of oxides for use in formulations (manufacturers publish their chemistries), each having physical and process side-effects that must be taken into account (recipes theoretically become 'material independent', oxides being supplied from whatever materials are at hand). To a body formulator, ceramic materials offer properties that influence forming and fired properties (e.g. plasticity, fluxing power, thermal expansion.

Related Information

A material storage rack

Tap picture for full size

This material storage area employs a rack to keep pails off the floor so the area can be hosed down easily. The materials in each pail are sealed in plastic bags or the pail is covered with a lid.

Refined 200 mesh materials are not guaranteed to be such

Tap picture for full size

Each of these eight pallets of kaolin are being sampled to screen them for oversize particles. The 50 gram samples needed can be taken without having to open the bags, they are filled through a valve at the top and it can be opened easily. Kaolins and ball clays especially are suspect and body manufacturers must be vigilant about this (each can tell you disaster stories about making product with faulty raw materials containing grit, carbon and iron particles). The samples will be washed through 70, 100 and 150 mesh screens to spot any particles that could introduce grit or fired speckle into the bodies.

Raw red burning clay stockpile

Tap picture for full size

The raw Plainsman M2 clay stockpile before it is ground. This is mined in Montana and imparts red color to various middle and low temperature clay bodies. It is a remarkably consistent material.

When both mineralogy and chemistry are shown on a data sheet

Tap picture for full size

Some material data sheets show both the oxide and mineralogical analyses. Dolomite, for example, is composed of calcium carbonate and magnesium carbonate minerals, these can be separated mechanically. Although this material participates in the glaze melt to source the MgO and CaO (which are oxides), it's mineralogy (the calcium and magnesium carbonates) specifically accounts for the unique way it decomposes and melts.

Do not rely on material data sheets, do the testing

Tap picture for full size

The cone 6 porcelain on the left uses Grolleg kaolin, the right uses Tile #6 kaolin. The Grolleg body needs 5-10% less feldspar to vitrify it to zero porosity. It thus contains more kaolin, yet it fires significantly whiter. Theoretically this seems simple. Tile #6 contains alot more iron than Grolleg. Wrong! According to the data sheets, Grolleg has the more iron of the two. Why does it always fire whiter? I actually do not know. But the point is, do not rely totally on numbers on data sheets, do the testing yourself.

What can you do using glaze chemistry? More than you think!

Tap picture for full size
And Insight-Live screenshot

There is a direct relationship between the way ceramic glazes fire and their chemistry. These green panels in my Insight-live account compare two glaze recipes: A glossy and matte. Grasping their simple chemistry mechanisms is a first step to getting control of your glazes. To fixing problems like crazing, blistering, pinholing, settling, gelling, clouding, leaching, crawling, marking, scratching, powdering. To substituting frits or incorporating available, better or cheaper materials while maintaining the same chemistry. To adjusting melting temperature, gloss, surface character, color. And identifying weaknesses in glazes to avoid problems. And to creating and optimizing base glazes to work with difficult colors or stains and for special effects dependent on opacification, crystallization or variegation. And even to creating glazes from scratch and using your own native materials in the highest possible percentage.

Bulk 2500 lb bulk bags of Pioneer Kaolin

Tap picture for full size

The material is much less dense than most other ceramic materials (that is why these bags are so tall). When moved the powder within becomes unstable and they are prone to falling over.

The recipe mixing area in the Plainsman Clays lab

Tap picture for full size

This is my lab work area of mineral, frit, chemical, stain and metal oxide powders for mixing test glazes and clay bodies. Not shown is my propeller mixer, perhaps the most important piece of equipment we have. And my plaster table for dewatering clay body slurries. Building up something like this, over time, is practical for any serious potter, most of these powders are inexpensive. Within minutes I can plan and enter a recipe into my Insight-live.com account, give it a code number, print it and weight it out.

An original container bag of Tricalcium Phosphate

Tap picture for full size

This is what a semi-trailer load (40,000 lbs) of talc looks like

Tap picture for full size

Talc is not nearly as dense as many other materials. If this was silica these pallets would be half this height.

Ceramic materials can vary widely in density

Tap picture for full size

A bag of magnesium carbonate beside a bag of feldspar. Although the former weighs 25 kg (vs. 22.7 kg for the feldspar), clearly it is a dramatically lighter (per volume unit) material. Lifting that bag of Mag Carb feels like lifting a pillow!

New Zealand Kaolin original container

Tap picture for full size

The original bag of this product in 2014.

50 lb bag of soda ash (or sodium carbonate).

Tap picture for full size

Soda Ash is soluble and is thus not useful in most ceramic glazes. However that very solubility makes it very useful to control the electrolytics of ceramic slurries. This is the dense variety, non-hydrous.

An original container of manganese dioxide

Tap picture for full size

This bag will give you a clue as to what manganese dioxide, MnO2, is mainly used for. Staining bricks.

Original container of Rockwood Lithium Carbonate

Tap picture for full size

Do ceramic material powders go bad?

Tap picture for full size

Many minerals are just ground up rocks, they were in the ground for millions of years (e.g. kaolin, feldspars, ball clays, bentonite, calcium carbonate, dolomite, talc, kyanite, wollastonite, etc), so the powders should last millions of years as well. Some are powderized man-made glasses and sintered solids, these are very stable (e.g. frits, stains). Other man-made materials are less stable and can hydrate or oxidize (e.g. carbonate colors, plaster), keep them sealed containers. Some materials are organic (e.g. Gum Arabic) and they can go bad in damp conditions, so keep them in a sealed container also.

Links

Projects Materials
Glossary Ceramics
This term generally refers to the industry that produces the non-metallic objects we use every day (like porcelain, tile, glass, stoneware).
Glossary Theoretical Material
In glaze chemistry, theoretical materials are used to represent what a material would be if it was uncontaminated and perfectly crystallized
URLs http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/index.htm
International Labour Organization Chemical Safety Database
URLs http://www.matweb.com/
MatWeb Materials Properties Database
By Tony Hansen
Follow me on

Got a Question?

Buy me a coffee and we can talk



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