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.
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Absorção de água (cerâmica)
A absorção de água AA = (massa úmida − massa seca)/massa seca·100% é a propriedade mais importante na classificação dos revestimentos cerâmicos — e diz tudo sobre o grau de sinterização da peça. Mede-se pesando a peça seca, fervendo-a (ou aplicando vácuo) em água para saturar os poros abertos, e pesando de novo: a água absorvida revela quanto de poro aberto existe. A escala (norma ISO 13006 / NBR) define os grupos: porcelanato (AA ≤ 0,5% — quase impermeável, denso, duríssimo, próprio para áreas externas e tráfego intenso); grês (0,5–3%); semigrês (3–6%); semiporoso (6–10%); e poroso (AA > 10% — os azulejos de parede, leves, fáceis de cortar, mas que não suportam gelo nem alto tráfego). Quanto menor a absorção, mais a peça vitrificou, mais resistente mecanicamente e ao manchamento e ao congelamento ela é (água nos poros, ao congelar, expande e trinca a peça — por isso pisos externos em climas frios exigem AA baixa). É também o que diferencia uma louça de mesa (vítrea, AA quase zero) de um vaso de barro (poroso, 'respira'). Informe a massa úmida e a seca.
Related Tools
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.
Knoop Hardness (HK)
Calculate the Knoop hardness, HK = 14.229 × F ÷ d², from the load F (kgf) and the long diagonal d (mm) of the elongated rhombic indentation left by a Knoop diamond indenter. The result, in kgf/mm² (HK), is used mainly for microhardness of brittle materials, coatings, glass and ceramics, and thin samples: the Knoop's elongated, shallow indentation measures narrow layers and hardness gradients better than Vickers and is less sensitive to microcracking. Enter the load and the long diagonal of the indentation.
Cobb (Paper Water Absorption)
Compute the Cobb value of a paper, Cobb = mass gain (g) / area (m²), in g/m², the amount of water absorbed by one face of the paper in a standardized time (usually 60 s). It measures resistance to water penetration, crucial in packaging papers, printing (glue/ink control) and products that contact liquids. A low Cobb indicates good sizing. Enter the mass gain and the tested area.
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.