Temperatures

73 pages

• Alumina Hydrate Decomposition (in the ceramic firing process)200-450C (392-842F) Alumina Hydrate Decomposition The decomposition occurs about 200-400C so poses no threat to creating bubbles in already-melting glazes. That being said, considerable amounts of water are generated and these could affect…
• Amorphous carbon burns from Texas Talc (in the ceramic firing process)750-850C (1382-1562F) Amorphous carbon burns from Texas Talc Texas talc contains carbon as CO2 in the dolomitic part of the ore (thus it is not detected as stand-alone talc in typical carbon burnoff testing). About 7% of the mass of the…
• Antimony volatilizes (in the ceramic firing process)1100C (2012F) Antimony volatilizes Starts at 1100C. Related Information Links Oxides Sb2O3 - Antimony Oxide Got a Question? https://digitalfire.com
• Barium carbonate melts (in the ceramic firing process)1360C (2480F) Barium carbonate melts Related Information Links Materials Barium Carbonate A pure source of BaO for ceramic glazes. This is 77% BaO and has an LOI of 23% (lost at CO2 on firing). Got a Question? https://digitalfire.com
• Bismuth Subnitrate decomposes (in the ceramic firing process)260C (500F) Bismuth Subnitrate decomposes Related Information Links Materials Bismuth Subnitrate Got a Question? https://digitalfire.com
• Body decomposition causes glaze bubbles (in the ceramic firing process)1065-1120C (1949-2048F) Body decomposition causes glaze bubbles Terra cotta and even high-kaolin white burning bodies can fill transparent glazes with clouds of tiny micro-bubbles , impairing the clarity of the glass. Related Information…
• Borax (in the ceramic firing process)120C (248F) Borax It loses crystallization water. Got a Question? https://digitalfire.com
• Boric Acid expels water (in the ceramic firing process)180C (356F) Boric Acid expels water Above 180C it loses crystallization water and the oxide B 2 O 3 melts at 300C. Got a Question? https://digitalfire.com
• Boron from Boric Acid melts (in the ceramic firing process)300C (572F) Boron from Boric Acid melts At 180C Boric acid loses crystallization water and the remaining B 2 O 3 melts at 300C. Thus this is the first material to enter the liquid phase in the fritting process. Got a Question?…
• Calcium carbonate decomposition (in the ceramic firing process)750-1000C (1382-1832F) Calcium carbonate decomposition Calcite converts to Quicklime on heating. If burned higher or too long it converts to dead burned lime. The decomposition process of this compound can generate tremendous amounts of…
• Calcium carbonate, talc finished gassing (in the ceramic firing process)815C (1499F) Calcium carbonate, talc finished gassing Related Information LOI horse race with surprising winners This picture has its own page with more detail, click here to see it. This chart compares the decompositional off-gassing (%…
• Calcium Sulphate decomposition (in the ceramic firing process)80-250C (176-482F) Calcium Sulphate decomposition Water vapor is expelled. Many clays contain small amounts of calcium sulphate. Related Information Links Minerals Gypsum Gypsum is hydrated calcium sulphate, CaSO4 2H2O. It is the…
• Chrome oxide decomposes (in the ceramic firing process)990C (1814F) Chrome oxide decomposes Related Information Links Materials Chrome Oxide Got a Question? https://digitalfire.com
• Chrome oxide melts (in the ceramic firing process)1990C (3614F) Chrome oxide melts Related Information Links Materials Chrome Oxide Got a Question? https://digitalfire.com
• Co3O4 decomposes (in the ceramic firing process)900C (1652F) Co3O4 decomposes At about 900C Co3O 4 decomposes to CoO and O2. Got a Question? https://digitalfire.com
• Colemanite reacts to water loss (in the ceramic firing process)400C (752F) Colemanite reacts to water loss It has a strong reaction to the state change associated with water elimination at 400C. Got a Question? https://digitalfire.com
• Common frits begin melting (in the ceramic firing process)760C (1400F) Common frits begin melting Common boron frits begin melting before talc , dolomite and calcium carbonate have completed gassing. A glaze containing 20% Ferro Frit 3134 , for example, could reach full density (zero porosity )…
• Comparison of frit melts at 1450F (in the ceramic firing process)787C (1448F) Comparison of frit melts at 1450F Related Information Melt fluidity comparison of frits - 1450F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1450F and held for 15 minutes. Frit 3134…
• Comparison of frit melts at 1500F (in the ceramic firing process)815C (1499F) Comparison of frit melts at 1500F Related Information Melt fluidity comparison of frits - 1500F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1500F and held for 15 minutes. Frit 3134…
• Comparison of frit melts at 1550F (in the ceramic firing process)843C (1549F) Comparison of frit melts at 1550F Related Information Melt fluidity comparison of frits - 1550F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1550F and held for 15 minutes. Frit 3134…
• Comparison of frit melts at 1600F (in the ceramic firing process)871C (1599F) Comparison of frit melts at 1600F Related Information Melt fluidity comparison - 1600F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1600F and held for 15 minutes. Frit 3134 is still…
• Comparison of frit melts at 1650F (900C) (in the ceramic firing process)1650C (3002F) Comparison of frit melts at 1650F (900C) Related Information LOI horse race with surprising winners This picture has its own page with more detail, click here to see it. This chart compares the decompositional off-gassing (%…
• Comparison of frit melts at 1700F (in the ceramic firing process)926C (1698F) Comparison of frit melts at 1700F Related Information Melt fluidity comparison of frits - 1700F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1700F and held for 15 minutes. 3110 is…
• Comparison of frit melts at 1750F (in the ceramic firing process)954C (1749F) Comparison of frit melts at 1750F Related Information Why does Gerstley Borate melt in two stages? Because it is two minerals. This picture has its own page with more detail, click here to see it. The ulexite in Gerstley…
• Comparison of frit melts at 1800F (in the ceramic firing process)982C (1799F) Comparison of frit melts at 1800F Related Information Frit Melt Fluidity Comparison - 1800F This picture has its own page with more detail, click here to see it. Fired at 350F/hr to 1800F and held for 15 minutes (I already did…
• Copper carbonate basic breakdown (in the ceramic firing process)1050C (1922F) Copper carbonate basic breakdown 7% weight loss involving partial loss of oxygen to form a mix of cuprous and cupric oxides Related Information Links Materials Copper Carbonate Basic This form of copper carbonate is the…
• Copper carbonate basic decomposes (in the ceramic firing process)300-330C (572-626F) Copper carbonate basic decomposes Loses 28% weight as it decomposes to to the heat stable CuO Related Information Links Materials Copper Carbonate Basic This form of copper carbonate is the article of commerce, a…
• Copper Carbonate decomposes to CuO (in the ceramic firing process)290C (554F) Copper Carbonate decomposes to CuO Copper carbonate decomposes at 290 °C, giving off carbon dioxide and leaving copper(II) oxide: CuCO 3 (s) → CuO (s) + CO2 (g) Related Information Links Materials Copper Carbonate A source of…
• Copper hydroxide decomposes to CuO (in the ceramic firing process)185C (365F) Copper hydroxide decomposes to CuO Loses about 18% weight as it decomposes to the heat stable CuO Related Information Links Materials Copper Hydroxide Got a Question? https://digitalfire.com
• Copper Oxide breakdown (in the ceramic firing process)1025-1325C (1877-2417F) Copper Oxide breakdown Copper becomes increasingly volatile and its crystalline structure breaks down Related Information Links Materials Copper Oxide Black The purest source of CuO copper oxide pigment used in…
• Copper oxide melts (in the ceramic firing process)1325C (2417F) Copper oxide melts Above 1025C copper becomes increasingly volatile and its crystalline structure breaks down, then it finally melts. Related Information Links Materials Copper Oxide Red Materials Copper Oxide Black The…
• Cristobalite inversion (alpha/beta) (in the ceramic firing process)210-280C (410-536F) Cristobalite inversion (alpha/beta) Occurs in cooling clay bodies at around 225C (and on heat-up for vitreous ware being refired). It is accompanied by a sudden volume change. Cristobalite , a less stable form of…
• Decarbonation (in the ceramic firing process)200-1000C (392-1832F) Decarbonation A wide range of carbonates are used in ceramics and each of these has its own thermal history. Within that is a range where they decompose to give off carbon dioxide or CO. Some of these materials lose…
• Decomposition of Barium Carbonate (in the ceramic firing process)1025C (1877F) Decomposition of Barium Carbonate The mechanisms of decomposition for BaCO 3 , CaCO 3 and SrCO 3 are similar (although of course not at the same temperature; calcium carbonate , for example, is much lower than this).…
• Dehydroxylation in kaolin, ball clay (in the ceramic firing process)450-650C (842-1202F) Dehydroxylation in kaolin, ball clay Dehydroxylation is the release of structurally bound hydroxyl groups from clay minerals such as kaolinite and ball clays during firing. Unlike dehydration (which removes physically…
• Densification (in the ceramic firing process)980C (1796F) Densification As common ceramic bodies mature their particles come into closer and closer contact and bond more and more. The earlier stages of this happen during sintering , the latter during vitrification . Densification is…
• Dolomite decomposition (in the ceramic firing process)650-900C (1202-1652F) Dolomite decomposition Dolomite reacts similar to calcium carbonate but its decomposition starts earlier. Got a Question? https://digitalfire.com
• Epsom salts decompose to lose water (in the ceramic firing process)150C (302F) Epsom salts decompose to lose water Related Information Links Materials Epsom Salts Got a Question? https://digitalfire.com
• Feldspar starts to react (in the ceramic firing process)1100C (2012F) Feldspar starts to react Dependent on size of particles, other particles present, time at temperature. But 1100C is only the start, not until 1200C will feldspar alone as the body flux , in practical percentages and particle…
• Fluorspar melts (in the ceramic firing process)1330C (2426F) Fluorspar melts Related Information Links Materials Fluorspar Got a Question? https://digitalfire.com
• Full carbon oxidation (in the ceramic firing process)370-700C (698-1292F) Full carbon oxidation Lignite and carbonaceous particles are burned away (lignite is most difficult to remove). In the case of inadequate time, heat penetration or insufficiently open structure, black particles (from…
• Gerstley Borate Melts Suddenly (in the ceramic firing process)870-900C (1598-1652F) Gerstley Borate Melts Suddenly It expands significantly between 1550 and 1600F and is melted by 1650. Through the entire heatup from 500F to 1600F it generates gases, totaling more than 20 percent. Related Information…
• Gerstley Borate stops gassing (in the ceramic firing process)760C (1400F) Gerstley Borate stops gassing Related Information LOI horse race with surprising winners This picture has its own page with more detail, click here to see it. This chart compares the decompositional off-gassing (% weight Loss…
• Hydrated lime decomposes (25% H2O) (in the ceramic firing process)512C (953F) Hydrated lime decomposes (25% H2O) Related Information Links Materials Hydrated Lime Got a Question? https://digitalfire.com
• Iron oxide red decomposes (in the ceramic firing process)1565C (2849F) Iron oxide red decomposes Fe 2 O 3 decomposes to Fe3O 4 . Releases oxygen. Related Information Links Materials Iron Oxide Red Red iron oxide is the most common colorant used in ceramic bodies and glazes. As a powder, it is…
• Kyanite decomposition and volume expansion (in the ceramic firing process)1100-1450C (2012-2642F) Kyanite decomposition and volume expansion The exact range depends strongly particle size, firing rate, soak time and purity of the kyanite . Fine particles convert earlier and more completely; coarse particles…
• Li2O Decomposes (in the ceramic firing process)1300C (2372F) Li2O Decomposes Got a Question? https://digitalfire.com
• Magnesite decomposition (in the ceramic firing process)500-600C (932-1112F) Magnesite decomposition The process of removing the CO2 from magnesite to produce light magnesium carbonate is often called magnesite decarbonization. There is variation in the temperature ranges given for this…
• Manganese Carbonate decomposes to MnO (in the ceramic firing process)200C (392F) Manganese Carbonate decomposes to MnO Release of carbon dioxide to give manganese(II) oxide: MnCO 3 -> MnO + CO2 Related Information Links Materials Manganese Carbonate Temperatures Decarbonation (200-1000) Glossary Carbon…
• Manganese compounds may begin to fume (in the ceramic firing process)932C (1709F) Manganese compounds may begin to fume Manganese metal fumes are toxic. It is difficult to verify the ceramic temperature where fuming could begin (welding is the context of almost all sources dealing with the topic). In…
• Manganese dioxide decomposes to MnO (in the ceramic firing process)470-1200C (878-2192F) Manganese dioxide decomposes to MnO This happens in stages: MnO2 to Mn2O 3 to Mn3O 4 and finally to MnO . The LOI is 18%. Related Information How do metal oxides compare in their degrees of melting? This picture has…
• Manganese oxide melts (in the ceramic firing process)1785C (3245F) Manganese oxide melts This temperature appears unlikely. In our own testing manganese dioxide melts vigorously far below cone 6 (~2200F). Related Information How do metal oxides compare in their degrees of melting? This…
• Metakaolin converts to spinel phase (in the ceramic firing process)950-1050C (1742-1922F) Metakaolin converts to spinel phase As kaolin is calcined past the metakaolin stage (400-600C) it goes through an exothermic re-crystallization to form a spinel intermediate phase. Related Information Links…
• Mullite converts to cristobalite (in the ceramic firing process)1100C (2012F) Mullite converts to cristobalite The calcination of kaolin is normally done between 400-600C. However higher temperatures are employed to produce the spinel and mullite phases. If temperature is allowed to exceed 1100°C, a…
• Neodymium oxide melts (in the ceramic firing process)2320C (4208F) Neodymium oxide melts Related Information Links Materials Neodymium Oxide Got a Question? https://digitalfire.com
• Organic burnout (in the ceramic firing process)300C (572F) Organic burnout Organics are literally burned out during first fire of ceramic bodies. Ball clays often contain significant organic material (the lignite imparts dark grey to even black coloration). Excessive organics and…
• Pore water removed in clay bodies (in the ceramic firing process)80-250C (176-482F) Pore water removed in clay bodies Occurs early in the first firing as residual pore (mechanical) water is removed from the clay body . Even after drying, most clay bodies retain some moisture (for example, dust-pressed…
• Praseodymium oxide decomposes (in the ceramic firing process)2300C (4172F) Praseodymium oxide decomposes Related Information Links Materials Praseodymium Oxide Got a Question? https://digitalfire.com
• Quartz inversion (alpha-beta) (in the ceramic firing process)540-600C (1004-1112F) Quartz inversion (alpha-beta) This term refers to an abrupt change in volume that occurs in quartz crystals when they are heated from the room temperature stable alpha phase to the beta crystal phase that exists above…
• Sintering and densification (in the ceramic firing process)850C (1562F) Sintering and densification As temperature increases for about 850C, particles can begin to bond even though no flux is present to produce a glass to cement particles together (called sintering ). As temperature increases,…
• Sodium Carbonate decomposes (in the ceramic firing process)850C (1562F) Sodium Carbonate decomposes Decomposition occurs at melting point. CO2 and NaO are emitted. Related Information Links Materials Sodium Carbonate Temperatures Decarbonation (200-1000) Got a Question? https://digitalfire.com
• Sodium Carbonate Dehydrates (in the ceramic firing process)370C (698F) Sodium Carbonate Dehydrates It loses 14% of its weight and changes from the so-called dense form to the light form. We are still measuring this temperature, but as of 700F it has not occurred. Related Information Links…
• Spinel phase meta kaolin converts to mullite (in the ceramic firing process)1050-1200+C (1922-2192F) Spinel phase meta kaolin converts to mullite Mullite begins forming at about 1050C, as temperature increases, the characteristic needle-shaped secondary mullite crystals grow within the feldspar glass of porcelains…
• Spodumene converts to beta phase (in the ceramic firing process)1082C (1979F) Spodumene converts to beta phase Undergoes an irreversible phase transition to yield beta-spodumene. This is accompanied by an expansion of ~30% and a decrease in specific gravity from 3.2 to 2.4. After conversion to its beta…
• Spodumene melts (in the ceramic firing process)1418-1428C (2584-2602F) Spodumene melts Related Information Links Materials Spodumene Spodumene is a lithium sourcing feldspar , an alternative to lithium carbonate to supply Li2O to ceramic glazes. Contains up to about 8% Li2O. Got a…
• Strontium carbonate decomposition (in the ceramic firing process)800-1100C (1472-2012F) Strontium carbonate decomposition Some data sheets (and Wikipedia) indicate that decomposition occurs at 1100C, the same as the melting temperature . Technical references are more specific, saying that decomposition…
• Strontium carbonate melts (in the ceramic firing process)1100C (2012F) Strontium carbonate melts Related Information Links Materials Strontium Carbonate A pure source of SrO for ceramic glazes. It contains 70% SrO and has an LOI of 30% (released as CO2 during firing). Got a Question?…
• Sulfur evolution (in the ceramic firing process)425-650C (797-1202F) Sulfur evolution This happens on first fire for many bodies. Sulfur is an impurity in many ball clays and related stoneware and earthenware raw clays, it occurs as calcium sulfate (selenite, the same mineralogy as…
• Talc crystalline water vaporizes (in the ceramic firing process)900-1000C (1652-1832F) Talc crystalline water vaporizes The crystalline (mechanical) water from talc evolves as a vapor. This is typically about 4% of the starting mass of the talc. Slower heating through this zone is appropriate for…
• Talc has finished gassing (in the ceramic firing process)900C (1652F) Talc has finished gassing Related Information LOI horse race with surprising winners This picture has its own page with more detail, click here to see it. This chart compares the decompositional off-gassing (% weight Loss on…
• Talc melts (in the ceramic firing process)1420C (2588F) Talc melts Related Information Links Materials Talc A source of MgO for ceramic glazes, a flux or thermal expansion additive in clay bodies , also used in the manufacture of cordierite. Got a Question? https://digitalfire.com
• Zinc oxide boils and volatilizes (in the ceramic firing process)850-950C (1562-1742F) Zinc oxide boils and volatilizes Related Information Links Materials Zinc Oxide A pure source of ZnO for ceramic glazes, it is 100% pure with no LOI . Got a Question? https://digitalfire.com
• Zircon melts, slowly dissolves (in the ceramic firing process)1550C (2822F) Zircon melts, slowly dissolves It has no definite melting point of zirconium silicate, but decomposition into zirconia and silica begins at 1550°C. Related Information Links Materials Zircon Got a Question?…