Firing Shrinkage (Ceramic)
Compute the linear firing shrinkage of a ceramic piece, FS = (L_dry − L_fired)/L_dry·100%, the size reduction during sintering in the kiln, when pores close and particles draw together. It is a critical dimensional-control parameter: porcelain tiles shrink a lot (~7%), while porous ceramics shrink little. Variations in shrinkage cause product miscalibration. Enter the dry and fired lengths.
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Firing shrinkage (ceramic)
When a ceramic piece goes into the kiln, it shrinks — sometimes dramatically. Firing shrinkage FS = (L_dry − L_fired)/L_dry·100% measures that reduction, driven by sintering: at high temperature the particles begin to bond to one another and the pores between them close, drawing the mass together and densifying the piece (the same principle as a snowball being packed). The more a body sinters (vitrifies), the more it shrinks — a porcelain tile, fired almost all the way to glass, shrinks around 6–8%, while a porous wall tile shrinks very little (around 0–1%). Keeping firing shrinkage under control is vital for dimensional control: the press mould is designed larger than the finished piece, offsetting exactly this shrinkage added to the drying shrinkage. When shrinkage drifts from firing to firing (through changes in clay composition, in temperature or in firing time), the pieces come out at different sizes — and have to be sorted into 'calibres', a classic headache of the wall and floor tile industry. Shrinkage is measured by marking a standard distance on the green piece and measuring it again once fired. Enter the dry length and the fired length.
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Total Shrinkage (Ceramic)
Compute the total linear shrinkage of a ceramic piece, TS = (L_wet − L_fired)/L_wet·100%, combining the drying and firing effects from the formed piece to the final product. It is the shrinkage the mold designer must compensate for: the cavity must be larger than the final piece by the total shrinkage, so the fired piece comes out at the exact size. Enter the wet (formed) and fired (final) lengths.
Water Absorption (Ceramic)
Compute the water absorption of a ceramic piece, WA = (wet mass − dry mass)/dry mass·100%, the amount of water the open pores absorb by immersion. It is the property that classifies ceramic tiles: porcelain (WA ≤ 0.5%, very dense and strong), stoneware, semi-stoneware, semi-porous and porous (wall tile, WA > 10%). The lower the absorption, the more sintered and resistant the piece. Enter the wet mass and the dry mass.
Clinker Lime Saturation Factor (LSF)
Computes the lime saturation factor of raw meal or clinker, the index that tells how close the lime present sits to the maximum that silica, alumina and iron oxide could combine with: LSF = 100 × CaO ÷ (2.8 × SiO₂ + 1.18 × Al₂O₃ + 0.65 × Fe₂O₃), with contents as mass percentages. It is the number one parameter in cement kiln control because it governs the split between alite and belite: a value near 100 means nearly all the lime combines and the clinker comes out rich in C₃S, with good early strength, but it demands a hotter burn and a narrow operating margin. Above 100 free lime is left over, hydrating late and expanding in concrete; below 90 the clinker is poor in alite and 3-day strength drops. The form without free lime correction was adopted, as used in raw meal control; on burnt clinker some laboratories subtract free CaO from the numerator, which lowers the index by one or two points. Enter the CaO, SiO₂, Al₂O₃ and Fe₂O₃ contents of the sample.
Drying Shrinkage (Ceramic)
Compute the linear drying shrinkage of a ceramic piece, DS = (L_wet − L_dry)/L_wet·100%, the size reduction as it loses the forming water before firing. The water that separated the clay particles evaporates and they draw together. Excessive or non-uniform drying shrinkage causes cracks and warping — which is why drying is slow and controlled. Enter the wet and dry lengths.
Sintering Relative Density
Compute the relative density of a sintered body, RD = (bulk density/theoretical density)·100%, the fraction of the maximum density (of the fully dense, pore-free material) the piece reached. It is the central measure of the degree of sintering: advanced ceramics aim for RD above 99% (almost pore-free) for maximum strength and properties. The residual porosity is 100% − RD. Enter the bulk (sintered) density and the theoretical density.
Bulk Density (Ceramic)
Compute the bulk (apparent) density of a ceramic, BD = dry mass/(wet mass − immersed mass), by Archimedes' method, considering the total piece volume (including pores). It is an indicator of the densification achieved in firing: higher bulk density means fewer pores and generally higher strength. Water density (1 g/cm³) is used in the hydrostatic weighing. Enter the dry, wet and immersed masses.
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