Whether you are a newcomer to a pottery studio or an experienced potter who decided to try a new kind of clay in his works, the choice of clay is the basic thing that will determine the success of your creations. Given the seemingly countless number of types of ceramic clays that are available in the market, it may be rather challenging to decide where to begin. This ultimate resource outlines the variables and applications of the primary differentiating kinds of clay to prepare you for pottery.
Texture and Workability
Coarse and fine clays are two major types which define the extent of how workable the material will be when sculpture is being made. In their solid states, they are plastic and rather slender and malleable to the extent that they can be moulded into various forms. They do not harden or become stiff when one is using them and they retain their shape when shaped and do not sink in, crack or break when drying. These buttery smooth clays are basic tools that any novice potter should have for handbuilding such as pinching, coiling and slabs. The two most famous examples of stoneware clay are red and white stoneware clays.
At the other textural extreme of grogged clay, there are small fragments of baked clay which make the clay surface rough and resembles sand paper. The surface is not smooth and this makes grogged clay more difficult to manipulate especially if one is new to pottery so it is ideal for those who have experience on the matter. When it comes to throwing, stiff grogged clay is quite delicate and therefore the process of wheel throwing stiff grogged clay may be tricky. This the texture does provide however: it minimizes shrinkage and crack in the drying and firing stages. An advantage that can be useful when working with huge sculptures or when using coiling technique.
Firing Temperature
Clays are made to undergo a process of vitrification or in other words, they are made to harden at specific temperature ranges of firing. Lower-fire clays reach their optimal stoneware hardness at a range of upto 2,100°F while the higher fired stoneware clays need kiln heat of between 2,100°F to 2,300°F to become fully set. The hardness of a clay body relies on the degree of firing and the formulation that you decide to use for your kiln befitting that peak temperature range.
Across those rather large firing classifications, some clays change their physical state as they cross through temperature barriers. For instance, a cone 6 stoneware clay has open porosity until 1175°C is reached then becomes non-porous up on firing at higher temperatures. These properties define its proper utilization or application like as flower vases or mugs or for other purposes like decorative items etc.
Color and Aesthetics
The nature of various clays used gives an extensive range of colours – bright white porcelain and red terra cotta clays together with the earthy colours of buff and gray stoneware clays. Matte clays are ideal since they provide a neutral base that can complement vibrant glazes before applying them. Various natural clays such as the terra cotta are very colored and when fired the pieces come with very bright colors that may not require any further surface enhancement.
Stains can also be added to clays in order to paint them, or leave streaks on them, to get the desired colouration. When selecting different colors, a recommended approach that one could adopt is to apply test tiles by using colored clays and glazes to find out the right color combination for the range. It is recommended to apply stains and pigments suitable to the firing range of the specific clay type used or else the end products will be marred with burnt-out blotches.
Enhanced surface finishes are not just limited to color, but also tangible, tangible appearance of the raw fired clay. Fine grained clays easily moulded make surfaced pottery where fine detailing on the surface of the pot can be made. Further, additional depth such as tiny pits and craze lines generate interest and offer decorative accent glazing concepts.
Sculptural or Functional Uses
Think about the types of sculptural and strictly utilitarian uses for your projects when choosing pottery clay. Sculptural art works give more importance to the art of sculpture with comparatively less strictures to some or the other structural issues. If for example the intended sculpture is a decorative item or a concept sculpture that doesn’t require strenuous or abrasive handling, then you can just concern yourself with getting the right type of clay that has the right workability, texture and firing characteristic to meet your artistic needs while not bothering much with extra hard end hardened strength which might not be of necessity in your sculpture.
Everyday functional pottery, the kind meant to be used on a daily basis and so on, demands that extra level of physical toughness and steadiness. Ceramics used to serve food and cook, utensils to wash, or bath products should withstand multiple washings, constant usage, and possibly even heat. When choosing clays for kitchen products and other daily used utensils, go for the fine grained, highly vitreous clays that produce non porous dense finished ceramic ware.
Environmental Factors
Think of the conditions within which you are going to use clay and where you will be exhibiting your creations. Humid climates are ideal for dense, low porosity clays due to the risk of absorbed water causing finished pottery to crack, weaken or leach minerals during outdoor display in the long term use.
Another area where ventilation plays an important role is studio space where you may be firing your own works. Those with lower firing temperatures and short firing times also reduces the amount of energy used and the heat it generates. It is a better environment for pottery just like when we are in our comfort zone. Lower turnaround also beneficial because it allows you to produce finished work much quicker.
In Summary
As with most materials used in pottery today, there are numerous types of pottery clay in the market today, but understanding the basic workability, firing range, porosity strength, and the variety of colors to choose from ensures that a beginner or an artist can effectively narrow down to the most appropriate clay type to use. Tri out several promising clays with sample projects that are designed for your favorite handbuilding or throwing methods. Find out which responds best before ordering in a bulk as your top quality polished finished products.
Different clay may not be ideal for all uses and therefore there is no ideal clay which fits all the said uses described above. Over time, you might discover more advanced specialization in clay types that you might have not initially favoured. Many master potters just keep on changing across many clay bodies for their entire practice – so don’t hesitate to try various formulae! As we have highlighted the clues for differentiating between various types of clay based on texture, color, firing requirement, and structural characteristic mentioned here, you will be well prepared to find your soul mates amongst clay.
