Loss on Ignition (Ceramic)
Compute the loss on ignition (LOI) of a ceramic raw material, LOI = (mass before − mass after ignition)/mass before·100%, the mass lost during heating at high temperature. It corresponds to the release of combined water (clay minerals), the burning of organic matter and the decomposition of carbonates (releasing CO₂). A high LOI indicates much clay/volatile matter and requires care to avoid defects (bubbles, cracks). Enter the mass before and after ignition.
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Loss on ignition (ceramics)
The loss on ignition (LOI) LOI = (mass before − mass after calcination)/mass before·100% measures how much a ceramic raw material loses in mass when heated to high temperature (typically around 1000 °C). Water is only part of the story — three phenomena release mass as gas: the escape of the chemically combined water held in the clay minerals (kaolinite, for instance, loses about 14% on dehydroxylation); the burnout of the organic matter present in the clay (roots, humus — which leave as CO₂); and the decomposition of carbonates such as calcite and dolomite (CaCO₃ → CaO + CO₂↑), which can release a great deal of CO₂. Knowing the LOI of every raw material matters for several reasons: it governs the final shrinkage and porosity (more volatiles leaving = more pores and more shrinkage); it demands care during firing (if the gases escape too fast, before the body has turned permeable, they cause blisters, bloating (black core) and cracks — hence the dwell steps built into the firing curve); and it shifts the mass balance of the recipe (a raw material with 20% LOI contributes less final mass than it appears to). Plastic clays and limestones have high LOI; quartz and most fluxes, very low. LOI is one of the first characterization tests run on any ceramic raw material. Enter the mass before and after calcination.
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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.
Stack Heat Loss (Siegert)
Calculate the heat loss through the exhaust gases by the Siegert formula, loss = K × (T_gas − T_air) ÷ CO₂, from the fuel factor K (~0.5 for natural gas, ~0.6 for oil), the gas and combustion air temperatures (°C) and the CO₂ percentage in the gases. The result, in %, is the largest energy loss of a boiler or furnace — the heat escaping hot through the stack. Lowering the gas temperature (with economizers and preheaters) and adjusting the excess air (which dilutes CO₂) minimizes this loss. The combustion efficiency is approximately 100% minus this loss. Enter the K factor, the temperatures and the CO₂.
Clay Activity (Skempton)
Computes clay activity as defined by Skempton, A = PI ÷ (% of particles finer than 2 μm), the ratio of the soil's plasticity index to the truly clay-sized fraction. It separates the clay mineral's effect from the mere amount of fines: two soils with the same PI behave very differently if one owes its plasticity to a little highly active clay and the other to a lot of inert clay. The usual classification is A < 0.75 inactive (kaolinite), 0.75 to 1.25 normal (illite) and A > 1.25 active (montmorillonite), the range where the expansive soils that warp pavements and shallow foundations are found. Enter the plasticity index and the clay fraction.
Vitrification Degree (Ceramic)
Estimate the vitrification degree of a ceramic, VD = (1 − WA/WA_green)·100%, comparing the current water absorption with that of the green (non-vitrified) material, as a measure of how much the glassy phase filled the pores during firing. Vitrification — the formation of molten glass that seals the pores — densifies the piece, lowers absorption and raises strength and impermeability. It is what turns porous clay into vitreous porcelain. Enter the current and green water absorptions.
Crop Growth Rate (CGR)
Computes the crop growth rate, CGR = (W₂ − W₁) ÷ (Δt × A), the canopy's dry-matter gain per unit of ground area per day between two destructive samplings. Unlike relative growth rate, which measures efficiency per gram of existing plant, CGR measures the productivity of the LAND — it is what you compare across row spacings, seeding densities and fertiliser levels, because it answers how much biomass each square metre of field produces per day. Peak values in well-managed C4 crops fall around 20 to 30 g/(m²·day), and the integral of the CGR curve over the season is total biological yield. Enter the initial and final dry masses, the interval between samplings and the ground area sampled.
Corrosion Rate (Mass Loss)
Calculate the corrosion rate by the mass-loss method, CR = 87.6 × W ÷ (D × A × t), from the mass loss W (mg), the material density D (g/cm³), the exposed area A (cm²) and the exposure time t (hours). The result, in mm/year, is the average speed at which the metal is consumed by corrosion — the key parameter to predict the service life of structures, piping and equipment and to set the corrosion allowance in design. Rates below 0.1 mm/year are usually acceptable. Enter the mass loss, density, area and time.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.