Ceramic fiber is a man-made vitreous wool of alumina and silica, sometimes with zirconia, that insulates furnace and heater linings at classification temperatures from 1260 °C (2,300 °F) in standard grades to 1430 °C (2,606 °F) in zirconia grades. Those classification temperatures come from a 24-hour shrinkage test, so what do they say about service?
Refractory ceramic fiber (RCF), also sold as aluminosilicate wool (ASW), carries CAS 142844-00-6 and is classified Carc. 1B H350i under CLP Annex VI (index 650-017-00-8, in application since 2010-12-01). It is one insulating form of refractory materials, next to bricks and monolithics.
EN 1094-1:2008 sets the classification temperature at the point where 24-hour shrinkage stays within 4 % for blanket or 2 % for board, and continuous use sits a typical 100 to 150 °C (180 to 270 °F) lower, according to that standard. ASTM C892-19(2024) sorts blanket into six Types from 732 °C (1,350 °F) to 1649 °C (3,000 °F). In the EU, exposure is capped at 0.3 f/ml (Directive (EU) 2017/2398, transposition by 2020-01-17).
Every value names its standard and edition, the product data sheet or the dated source it comes from; see our methodology and fact-checking process.
The identity, classification and hazard data of ceramic fiber are summarized in the table below.
| Attribute | Value |
|---|---|
| Definition | Man-made vitreous (glassy) fiber of Al2O3 and SiO2, with ZrO2 in zirconia grades, fiberized from a melt |
| Identity | CAS 142844-00-6 "Refractories, fibers, aluminosilicate"; ECHA list number 604-314-4 (not an EINECS number) |
| Class range (CAS definition) | SiO2 45 to 60 %, Al2O3 28 to 55 %, ZrO2 < 18 % by mass (quoted in Morgan SDS 1013) |
| Classification temperature, named products | 1260 °C (2,300 °F) standard and high-purity grades; 1425 to 1430 °C (2,597 to 2,606 °F) zirconia and chromia grades (grades table) |
| Classification rules | EN 1094-1:2008 (shrinkage-based); ASTM C892-19(2024) (Types by maximum use temperature) |
| CLP | Carc. 1B H350i, Annex VI index 650-017-00-8, notes A and R, since 2010-12-01 |
What Is Ceramic Fiber?#
Ceramic fiber is a high-temperature insulation wool made by melting alumina and silica near 2000 °C (3,632 °F) and spinning or blowing the melt into fibers of 1.2 to 3 µm nominal diameter. The fiber leaves the melt as glass, and bulk wool contains no binder, so the material is a loose, inorganic mat of fine filaments with about half the melt ending as non-fibrous shot (NIOSH criteria document 2006-123).
EN 1094-1:2008 groups ceramic fiber with alkaline earth silicate (AES) wool and polycrystalline wool as high-temperature insulation wool (HTIW), defined as man-made mineral wool suitable for heat insulation above 600 °C (1,112 °F). Of the three HTIW families, RCF is the alumino-silicate one, and the full family sits under refractory insulation.
Classification Temperature Under EN 1094-1:2008#
EN 1094-1:2008 sets the classification temperature of a ceramic fiber product as the temperature at which its 24 h permanent linear change stays within 4 % (blankets, felts, mats, papers) or 2 % (boards, preformed shapes).
The two shrinkage limits of the EN 1094-1:2008 rule are compared in the table below.
| Product form | PLC limit after 24 h | Stated as |
|---|---|---|
| Blankets, felts, mats and papers | ≤ 4 % | nearest 50 °C, 850 to 1800 °C (1,562 to 3,272 °F) |
| Boards and preformed shapes | ≤ 2 % | nearest 50 °C, 850 to 1800 °C (1,562 to 3,272 °F) |
EN 1094-1:2008 was published on 2008-07-01 and replaced EN 1094-1:1997; CEN decided on 2026-10-21 to revise it. The classification temperature is a test result on an isothermal sample, not a service rating, which is why a blanket and a board of the same fiber carry different numbers: the board must hold half the shrinkage of the blanket at its class point. The same standard lists the tests behind a wool data sheet: thickness under 350 or 725 Pa, bulk density after drying at 110 ± 5 °C (230 ± 9 °F), resilience, permanent linear change, tensile strength, and moisture and organic content.
ASTM C892 Types and Grades for Fiber Blanket#
ASTM C892-19(2024) sorts high-temperature fiber blanket into six Types by maximum use temperature, from Type I at 732 °C (1,350 °F) to Type V at 1649 °C (3,000 °F), and into Grades 3 to 12 by density.
The Types and Grades of ASTM C892-19(2024) are compared in the table below; inch-pound values govern and SI values are computed.
| Type | Max use temperature, °C (°F) | Grade | Density, lb/ft³ (kg/m³) | Max k at 2,000 °F (1093 °C) mean, BTU·in/(h·ft²·°F) (W/(m·K)) | Min tensile, lb/in (N/m) |
|---|---|---|---|---|---|
| I | 732 (1,350) | 3 | 2.5 to 4 (40 to 64) | n/a | 1.0 (175) |
| II | 871 (1,600) | 4 | 3.4 to 5.5 (54 to 88) | 5.47 (0.79) | 1.5 (263) |
| IIA | 1093 (2,000) | 6 | 5.1 to 8 (82 to 128) | 4.75 (0.69) | 2.0 (350) |
| III | 1260 (2,300) | 8 | 6.8 to 10.5 (109 to 168) | 4.18 (0.60) | 3.0 (525) |
| IV | 1427 (2,600) | 10 | 8.5 to 13 (136 to 208) | n/a | 4.0 (701) |
| V | 1649 (3,000) | 12 | 10.2 to 16 (163 to 256) | n/a | 5.0 (876) |
The specification belongs to ASTM Committee C16 on Thermal Insulation, covers blanket from ambient up to 1649 °C (3,000 °F) and sets apparent thermal conductivity, density, temperature of use, non-fibrous content, linear shrinkage and tensile strength; its inch-pound units govern, and Type III is 2,300 °F (1260 °C), not 2,400 °F. Shot content is measured after the specimen is fired for 5 h at the maximum use temperature of its Type, and every clause sits in the ASTM C892 high-temperature fiber blanket specification.
Names: Ceramic Fibre, Ceramic Wool, Aluminosilicate Wool and RCF#
Five names in trade and regulation describe the same material class, listed below.
- Refractory ceramic fiber (RCF): the regulatory and technical name used by NIOSH, OSHA and CLP.
- Aluminosilicate wool (ASW): the EN 1094-1:2008 family name; the EU Candidate List entries read "Aluminosilicate Refractory Ceramic Fibres" and "Zirconia Aluminosilicate Refractory Ceramic Fibres".
- Ceramic wool and ceramic fiber wool: trade names for the loose wool, with "cerawool" used in India.
- Ceramic fibre: the UK and EU spelling of the same product.
- Kaowool and fiberfrax: trade names used generically in the US for any ceramic fiber.
What Is Ceramic Fiber Made Of?#
Ceramic fiber is 45 to 60 % SiO2, 28 to 55 % Al2O3 and less than 18 % ZrO2 by mass, the class range of the CAS definition quoted in Morgan SDS 1013. The CLP and Candidate List definition adds a ceiling: Na2O, K2O, CaO, MgO and BaO together stay at or below 18 % by weight, which separates RCF from AES wool.
The composition bases of ceramic fiber, from definition to research reference fibers, are compared in the table below (mass %).
| Basis | SiO2 | Al2O3 | ZrO2 | Other |
|---|---|---|---|---|
| CAS definition class range | 45 to 60 | 28 to 55 | < 18 | alkali and alkaline-earth oxides ≤ 18 (CLP definition) |
| EN 1094-1:2008 typical ASW (Table 2) | 44 to 54 | 46 to 56 | n/a | < 1 |
| EN 1094-1:2008 typical alumino-zirconium-silicate wool (Table 3) | > 48 | < 37 | < 20 | < 1 |
| NIOSH reference fiber RCF1 (kaolin) | 47.7 | 48 | n/a | Fe2O3 0.97, TiO2 2.05 |
| NIOSH reference fiber RCF2 | 50 | 35 | 15 | n/a |
| NIOSH reference fiber RCF3 (high purity) | 50.8 | 48.5 | n/a | Fe2O3 0.16 |
The EN 1094-1:2008 ranges are typical compositions, not requirements, and the NIOSH fibers RCF1 to RCF3 are research references from criteria document 2006-123. The feedstock is calcined kaolin or a blend of alumina and silica, with zircon added for zirconia grades, melted near 2000 °C (3,632 °F); the kaolin route explains the Fe2O3 and TiO2 in RCF1, which the high-purity RCF3 nearly lacks.
Standard, High-Purity, Zirconia and Chromia Grades#
Four grades cover most ceramic fiber: standard (kaolin), high-purity, zirconia and chromia-doped, each identified here by one named product.
The four grades are compared in the table below, with one named product and its data-sheet chemistry per grade.
| Grade | Named product (maker data sheet) | Chemistry, mass % | Classification temperature |
|---|---|---|---|
| Standard (kaolin) | Kaowool blanket (Morgan Thermal Ceramics) | Al2O3 45, SiO2 50 to 55, Fe2O3 1.0, TiO2 2.2 | 1260 °C (2,300 °F) |
| High-purity | Durablanket HP-S (Unifrax) | Al2O3 43 to 47, SiO2 53 to 57 | 1260 °C (2,300 °F) |
| Zirconia | Durablanket 2600 (Unifrax); zirconia feed: zircon and stabilized zirconia | Al2O3 29 to 31, SiO2 53 to 55, ZrO2 15 to 17 | 1430 °C (2,606 °F) |
| Chromia-doped | Cerachrome (Morgan Thermal Ceramics) | Al2O3 43, SiO2 54, Cr2O3 2.8 | 1425 °C (2,597 °F) |
The step from 1260 °C to 1425 or 1430 °C follows the melt additions, not the alumina level: the zirconia grade carries only 29 to 31 % Al2O3, against 43 to 47 % in the high-purity grade, yet classifies 170 °C (306 °F) higher.
Which Additives and Binders Does Ceramic Fiber Contain?#
Bulk ceramic fiber contains no binder: its grade is set by melt additions, and binders enter only when the fiber is converted into board, paper, textiles or mastics. Three melt additions shift the grade, listed below.
- Zirconia (ZrO2): about 15 % of the melt (15 % in Cerachem, 15.2 % in Kaowool SZr) raises the classification temperature to 1425 to 1430 °C (2,597 to 2,606 °F) and lowers shrinkage.
- Chromia (Cr2O3): 2.8 % in Cerachrome reduces shrinkage at temperature in the chromia-doped grade.
- Boron, titanium and zirconium oxides: stabilizers that alter durability and heat resistance, according to NIOSH criteria document 2006-123, citing the RCF industry coalition (1996).
Needled blanket stays binder-free, so it gives no smoke on first firing. Converted forms carry a binder chosen for the job: latex for flexible paper, organic and inorganic binders for wet-formed board, an organic carrier for yarn, and colloidal silica (silica sol) for moldable mastics and hardened fiber faces, the role covered under colloidal silica binders.
Ceramic Fiber Properties: Standard Requirements and Typical Values#
Ceramic fiber data come in two kinds: class limits that a standard sets, such as the 4 % shrinkage limit of EN 1094-1:2008 or the conductivity ceiling of an ASTM C892-19(2024) Grade, and typical values that one named product reached. A third kind, the NIOSH class ranges of criteria document 2006-123, describes the fiber itself (diameter, length, density, softening) and never sets a product limit.
The standard requirements and typical values of ceramic fiber are compared in the table below.
| Property | Standard requirement | Typical value (product or class range) | Method or source |
|---|---|---|---|
| Classification temperature | EN 1094-1:2008 rule; C892 Type limit | 1260 °C (2,300 °F) Kaowool, Cerablanket, Durablanket S and HP-S; 1425 °C (2,597 °F) Cerachem, Cerachrome; 1430 °C (2,606 °F) Durablanket 2600 | EN 1094-1:2008 |
| Continuous use or recommended operating temperature | n/a | continuous use 1093 °C (2,000 °F) Kaowool, 1315 °C (2,400 °F) Cerachem, 1371 °C (2,500 °F) Cerachrome; recommended operating 1177 °C (2,150 °F) Durablanket S and HP-S, 1343 °C (2,450 °F) Durablanket 2600 | data sheets (°F printed, °C calculated) |
| permanent linear change | ≤ 4 % at classification temperature (blanket, EN 1094-1:2008) | 1.5 % at 1000 °C, 2.2 % at 1100 °C, 3.0 % at 1200 °C, 5.5 % at 1300 °C, Kaowool Blanket S; 1.0 % at 1200 °C, 2.0 % at 1300 °C, 3.0 % at 1400 °C, Kaowool Blanket SZr | EN 1094-1:2008, 24 h |
| thermal conductivity of refractories and insulation | C892 Grade 8 max 4.18 BTU·in/(h·ft²·°F) (0.60 W/(m·K)) at 2,000 °F (1093 °C) mean | 0.06, 0.10, 0.15, 0.20, 0.27, 0.34 W/(m·K) (0.42, 0.69, 1.04, 1.39, 1.87, 2.36 BTU·in/(h·ft²·°F)) at 200, 400, 600, 800, 1000, 1200 °C, Cerachem blanket 128 kg/m³ (8 lb/ft³) | ASTM C201 |
| Tensile strength | C892 Grade 8 min 3.0 lb/in (525 N/m) | 30, 70, 90, 110 kPa (4.4, 10.2, 13.1, 16.0 psi) at 64, 96, 128, 160 kg/m³ (4, 6, 8, 10 lb/ft³), Cerablanket | EN 1094-1:2008 method |
| Fiber diameter | n/a | 1.2 to 3 µm nominal (class range, NIOSH); 2.5 to 3.5 µm mean, Durablanket S | NIOSH 2006-123; data sheet |
| Fiber length | n/a | 2 to 254 µm (class range) | NIOSH 2006-123 |
| Specific gravity | n/a | 2.6 to 2.7 g/cm³ (162 to 169 lb/ft³) (class range) | NIOSH 2006-123 |
| Softening point | n/a | 1700 to 1800 °C (3,092 to 3,272 °F) (class range) | NIOSH 2006-123 |
| Melting point | n/a | 1760 °C (3,200 °F), Durablanket S and HP-S | data sheet |
| Shot (non-fibrous) content | C892 limit per Type, see the ASTM C892 page | 20 to 50 % by mass in bulk (class range) | NIOSH 2006-123 |
| Specific heat | n/a | 1.13 kJ/(kg·K) (0.27 BTU/(lb·°F)) at 1093 °C (2,000 °F), Durablanket | data sheet |
| Dissolution rate at pH 7.4 | n/a | 1 to 10 ng/(cm²·h) (class range) | NIOSH 2006-123 |
| All properties and test methods | see properties of refractory materials | n/a | n/a |
Conductivity values compare only at the same mean temperature, density and method. The C892 ceiling applies at a 1093 °C (2,000 °F) mean temperature across the sample, while the product series is reported at stated temperatures by the ASTM C201 calorimeter method, so the two columns are not a pass or fail check of each other; 1 W/(m·K) equals 6.933 BTU·in/(h·ft²·°F). R-values and thickness by density belong to the ceramic fiber blanket.
Classification Temperature Versus Continuous Use Temperature#
Ceramic fiber runs continuously about 100 to 150 °C (180 to 270 °F) below its classification temperature, the margin EN 1094-1:2008 gives for amorphous wools.
Kaowool Blanket S shows why: its 24 h shrinkage rises from 3.0 % at 1200 °C (2,192 °F) to 5.5 % at 1300 °C (2,372 °F), so the 4 % limit falls between the two, and the blanket is classified at 1260 °C (2,300 °F). Shrinkage accelerates above the class point (0.8 % more from 1100 to 1200 °C, 2.5 % more from 1200 to 1300 °C), which is why the operating ratings in the properties table sit below each classification temperature.
NIOSH criteria document 2006-123 gives the class view: the maximum end-use temperature of RCF runs from about 1050 to 1425 °C (1,922 to 2,597 °F), depending on chemistry. The upper end belongs to zirconia and chromia chemistries, the lower end to the kaolin grade.
Devitrification Above 985 °C (1,805 °F)#
Ceramic fiber leaves the melt as glass and crystallizes in service: mullite forms from about 985 °C (1,805 °F) and cristobalite from about 1200 °C (2,192 °F), per Unifrax MSDS M0001 (2009), a producer value.
NIOSH defines after-service RCF as fiber exposed above about 1000 °C (1,832 °F) and partly converted to cristobalite, and it studies that state with reference fiber RCF4, the heated form of RCF1. Devitrified fiber turns brittle and the hot face shrinks, and the cristobalite matters because respirable crystalline silica, quartz and cristobalite, is IARC Group 1 (Monograph 100C, 2012), a higher class than the Group 2B of the fiber itself.
Which Standards Classify and Test Ceramic Fiber?#
Ceramic fiber is classified by EN 1094-1:2008 in Europe and specified as blanket by ASTM C892-19(2024) in the US, and the two do not convert: EN 1094-1 reports a shrinkage-based classification temperature, C892 a maximum use temperature per Type. A product classified at 1260 °C and a C892 Type III blanket share one number but answer two different questions.
The standards that classify, test and inspect ceramic fiber are compared in the table below.
| Purpose | ASTM (edition) | ISO / EN (edition) | Note |
|---|---|---|---|
| Fiber classification | C892-19(2024), blanket Types and Grades | EN 1094-1:2008, classification temperature | not interchangeable |
| Thermal conductivity | C201-24 (calorimeter) | n/a | method named with every value |
| Insulating firebrick, for contrast | C155-97(2022) | ISO 2245:2006, excludes ceramic fiber products | ASTM C155 and ISO 2245 |
| Fiber lining quality control | API Std 976, 2nd edition (October 2024) | n/a | API 936 and API 976 refractory installation quality control |
ASTM C155-97(2022) and ISO 2245:2006 classify insulating firebrick by reheat change and density, and ISO 2245:2006 states that ceramic fiber products fall outside it, so a firebrick group number never describes a wool. In refineries, API Std 976, 2nd edition (October 2024), covers installation quality control, inspection and testing of AES and RCF fiber linings, and conductivity claims cite ASTM C201-24.
Where Is Ceramic Fiber Used in Industrial Linings?#
Ceramic fiber lines fired heaters, ethylene crackers and reformer headers in petrochemical plants, reheat and forge furnaces and annealing covers in steel plants, glass-furnace crown backup insulation, and boiler, incinerator and stack linings.
The industries and zones that use ceramic fiber are compared in the table below.
| Industry | Zone | Page |
|---|---|---|
| Petrochemical | Fired heaters, ethylene crackers, reformer headers, ducts | refinery and petrochemical refractories |
| Iron and steel | Reheat and forge furnaces, annealing covers, soaking pit seals | refractories for iron and steel |
| Steel reheating | Skid pipe insulation | reheating furnace refractories |
| Glass | Crown backup insulation | glass furnace refractories |
| Power and incineration | Boiler, incinerator and stack linings, expansion joints | boiler refractory |
Ceramics plants add kiln linings to the list. Low heat storage and low conductivity suit furnaces that cycle, such as batch annealing covers and reheat furnace doors, because a light fiber lining stores little heat. Ceramic fiber is unaffected by most chemicals except hydrofluoric acid, phosphoric acid and strong alkalis, according to Unifrax product literature.
Product Forms: Bulk, Blanket, Modules, Board, Paper, Textiles and Mastics#
Ceramic fiber reaches the lining in seven forms, from loose bulk fiber to colloidal silica bonded mastics, and each form has its own page.
The seven product forms, their binders and their pages are compared in the table below.
| Form | What it is | Binder | Page |
|---|---|---|---|
| Bulk fiber | Loose wool for packing and further conversion | none | this page |
| Blanket | Needled mat of air-laid fiber | none | ceramic fiber blanket |
| Modules | Blanket compressed to about 160 to 300 kg/m³ (10 to 19 lb/ft³) (EN 1094-1:2008 definition) | none | ceramic fiber modules |
| Board and shapes | Wet-formed rigid board and vacuum-formed shapes | organic and inorganic binders | ceramic fiber board and vacuum-formed shapes |
| Paper | Thin wet-laid felt | 7 % latex in RubberMill ceramic fiber paper | ceramic fiber paper and gaskets |
| Textiles | Fiber spun on a viscose carrier, reinforced with glass filament or stainless steel (Luyangwool) | organic carrier | ceramic fiber textiles |
| Mastics | Moldable fiber paste: fiber 15 to 50 %, colloidal silica 40 to 80 %, water 0 to 30 % (Morgan SDS 1013) | colloidal silica | ceramic fiber rigidizers, coatings and mastics |
How Are Ceramic Fiber Linings Installed and Heated Up?#
Ceramic fiber is installed as a converted product (needled blanket, folded modules, board or mastic), never sprayed as loose fiber, and binder-free forms need no cure before the first heat. ECFIA and Morgan SDS 1013 advise against spraying the fiber. Fiber placement is one installation method next to casting, gunning and bricklaying, all compared under refractory installation methods.
Anchors set the hot-face limit of a blanket or module lining, because the metal or ceramic hardware must survive the temperature at its tip; alloy limits and stud spacing belong to the anchoring practice, not to the fiber grade.
API Std 976, 2nd edition (October 2024), sets installation quality control, inspection and testing for AES and RCF fiber linings in refineries, the fiber counterpart of the monolithic standard API Std 936.
Binder-free blanket gives no smoke on first firing, while the organic binders in board and paper burn out with smoke on the first heat-up. Binder-free fiber needs no cure, and the hold-and-ramp programs of refractory dry-out and heat-up schedules apply only to castable layers next to it.
Three practice pages and tools for fiber lining design and hardware are listed below.
- refractory anchors: stud and module hardware for blanket and module linings.
- refractory lining: working, safety and insulating layers: where the fiber layer sits in a lining.
- refractory heat loss and lining thickness calculator: fiber thickness against shell temperature.
Why Do Ceramic Fiber Linings Fail, and How Are They Inspected?#
Ceramic fiber linings fail by shrinkage that opens joints after the lining runs above its classification temperature, and by devitrification that embrittles the hot face. Fluxing, chemical attack and erosion add three further modes.
The failure modes of ceramic fiber linings, their causes and their checks are compared in the table below.
| Failure | Cause | Check |
|---|---|---|
| Shrinkage gaps at joints | Service above the classification temperature | PLC on retained samples, EN 1094-1:2008; see refractory failure modes |
| Hot-face embrittlement | Devitrification to mullite and cristobalite | XRD of hot-face fiber |
| Fluxing and chemical attack | Alkalis, hydrofluoric acid, phosphoric acid, strong alkali | Chemistry review of the gas and deposits |
| Erosion | Gas above 12.2 m/s (40 ft/s) on plain blanket (Unifrax guidance) | Rigidized face or other form |
| Insulation loss | Any of the above | ASTM C201-24 on samples; shell temperature; see refractory inspection and quality control |
Inspection compares a retained sample of the original product with fiber taken from the hot face: permanent linear change after 24 h by EN 1094-1:2008, conductivity by ASTM C201-24 and XRD for crystalline phases. Plain needled blanket faces stay below 12.2 m/s (40 ft/s) of gas velocity in Unifrax product guidance, which is producer guidance and not a standard requirement.
Ceramic Fiber Health and Safety Rules#
Refractory ceramic fiber is classified Carc. 1B H350i (may cause cancer by inhalation) under CLP Annex VI index 650-017-00-8 with notes A and R, in application since 2010-12-01 (ATP01, Regulation (EC) No 790/2009). Note R lifts the classification only for fibers whose length-weighted geometric mean diameter, less two geometric standard errors, exceeds 6 µm. Aluminosilicate RCF joined the ECHA Candidate List on 2010-01-13 and zirconia aluminosilicate RCF on 2011-12-19; RCF is not on Annex XIV (Commission Regulation (EU) 2017/999, recital 23), and REACH Annex XVII entry 28 bars supply to the general public.
The EU binding limit is 0.3 f/ml as an 8-hour TWA (Directive (EU) 2017/2398, transposition by 2020-01-17). In the US, NIOSH recommends 0.5 f/cm³ (criteria document 2006-123), ACGIH sets a TLV of 0.2 f/cc (1999, A2), Cal/OSHA a PEL of 0.2 f/cc, and federal OSHA has no RCF-specific PEL (OSHA chemical data 951, read 2026-10-27). IARC classifies RCF as Group 2B (Vol. 43, 1988; Vol. 81, 2002). The product SDS governs each delivery.
The classification, register entries and exposure limits of refractory ceramic fiber are compared in the table below.
| Topic | Rule or value | Instrument and date |
|---|---|---|
| CLP | Harmonised CLP Annex VI: Carc. 1B H350i (index 650-017-00-8), GHS08, Danger; notes A and R | ATP01, Regulation (EC) No 790/2009, in application since 2010-12-01 |
| SVHC | Aluminosilicate RCF 2010-01-13; zirconia aluminosilicate RCF 2011-12-19; carcinogenic (Article 57a) | ECHA Candidate List, read 2026-10-27 |
| Authorization | Not on Annex XIV | Commission Regulation (EU) 2017/999, recital 23; ECHA authorization list read 2026-10-27 |
| Supply | No supply to the general public as substance or in mixtures at or above the classification limit | REACH Annex XVII entry 28, Appendix 2 (Carc. 1B), read 2026-10-27 |
| REACH | Registered, CAS 142844-00-6, list 604-314-4 | ECHA CHEM, checked 2026-10-27 |
| EU exposure limit | 0.3 f/ml, 8 h TWA | Directive (EU) 2017/2398, transposition by 2020-01-17 |
| US exposure limits | NIOSH REL 0.5 f/cm³ (TWA up to 10 h); ACGIH TLV 0.2 f/cc (1999), A2; Cal/OSHA PEL 0.2 f/cc; no federal OSHA PEL | NIOSH 2006-123 (2006); OSHA chemical data 951, read 2026-10-27 |
| IARC | Group 2B | IARC Monographs Vol. 43 (1988), Vol. 81 (2002) |
| Waste | 0.1 % RCF or more makes waste hazardous by HP 7 | Regulation (EU) No 1357/2014, HP 7 (Carc. 1A or 1B constituent ≥ 0.1 %) |
| Exposure control and tear-out | see ceramic fiber (RCF) health rules | n/a |
Exposure control, after-service fiber and disposal are covered on three linked pages, listed below.
- ceramic fiber (RCF) health rules: exposure control, tear-out and the AES and PCW alternatives.
- crystalline silica and cristobalite in refractories: cristobalite in after-service fiber.
- spent refractory recycling and disposal: HP 7 waste classification of used fiber.
Ceramic Fiber Grades, Packaging and Sourcing#
Ceramic fiber is bought by grade and form, and a data sheet (Kaowool, Fiberfrax, Isowool or any other) becomes comparable only when it states the classification temperature with its test, the chemistry with ZrO2 or Cr2O3 content, and density. Six checks turn any ceramic fiber data sheet into a comparable offer, listed below.
- Confirm the classification rule: EN 1094-1:2008 shrinkage class or an ASTM C892-19(2024) Type.
- Read the chemistry and the grade: standard, high-purity, zirconia or chromia, with ZrO2 or Cr2O3 in mass %.
- Check the density against the C892 Grade limits, for example 6.8 to 10.5 lb/ft³ (109 to 168 kg/m³) for Grade 8.
- Read the conductivity with its method and mean temperature, never as a bare number.
- Check the shrinkage at the planned hot-face temperature, not only at the class point.
- Ask for the SDS with the CLP index 650-017-00-8 line.
Quantity, form, packaging and delivery country complete the request, because they change the offer as much as the grade does. Producers, distributors and buying routes for fiber and other classes are described under refractory manufacturers and suppliers.
What Does Ceramic Fiber Cost?#
Industrial ceramic fiber is priced per quote, and five factors set that price: grade and classification temperature, product form and density, quantity and packaging, freight, and installation.
The five price factors and what the buyer states for each are compared in the table below.
| Price factor | What the buyer states |
|---|---|
| Grade and classification temperature | Standard, high-purity, zirconia or chromia; °C (°F) with its rule |
| Form and density | Bulk, blanket, modules, board, paper, textiles or mastic; kg/m³ (lb/ft³) or C892 Grade |
| Quantity and packaging | Rolls, cartons, bags or pallets; total quantity |
| Freight | Delivery country and Incoterms |
| Installation | Supply only or installed |
A list price for a single blanket roll is not an industrial price, because it omits grade certification, volume and freight terms.
Ceramic Fiber Compared With AES Wool, Polycrystalline Wool and Firebrick#
Ceramic fiber competes with AES wool below about 1200 to 1300 °C, with polycrystalline wool above about 1400 °C, and with insulating firebrick where a lining must carry load.
AES wool falls under CLP index 650-016-00-2 (Carc. 2 H351), is not classified when Note Q is met and has no EU binding limit; the full set of differences between AES wool and refractory ceramic fiber sits under AES wool vs refractory ceramic fiber.
The alternatives to ceramic fiber, their rules and temperatures are compared in the table below.
| Alternative | Rule | Temperature (basis) | Page |
|---|---|---|---|
| AES wool | CLP 650-016-00-2, Carc. 2 H351, not classified when Note Q is met | Superwool Plus 1200 °C (2,192 °F), Superwool HT 1300 °C (2,372 °F), Superwool XTRA 1450 °C (2,642 °F) (Morgan data) | AES and low bio-persistence wool |
| Polycrystalline wool | EN 1094-1:2008, about 72 to 97 % Al2O3 | above about 1400 °C (2,552 °F) | polycrystalline wool |
| Insulating firebrick | ASTM C155-97(2022), ISO 2245:2006 | see the firebrick page | insulating firebrick |
| Microporous | ASTM C1676/C1676M-25 | 80 to 1150 °C (176 to 2,102 °F) (scope) | microporous insulation |
| Full fiber vs brick comparison | n/a | n/a | ceramic fiber vs insulating firebrick |
ECFIA, the European industry association, reports that AES and polycrystalline wool have replaced about 50 % of alumino-silicate wool products over three decades. The EU Roadmap on Carcinogens advises considering AES wool or non-fibrous light refractories where they are technically suitable.
Ceramic Fiber vs Mineral Wool#
Ceramic fiber is one of the high-temperature insulation wools, about 2 % of EU synthetic mineral wool production (ECFIA), and it differs from glass, rock and slag wool in temperature range and hazard class.
IARC Monographs Volume 81 (2002) places insulation glass wool, rock wool and slag wool in Group 3 and refractory ceramic fiber in Group 2B. The temperature line runs at 600 °C (1,112 °F): EN 1094-1:2008 reserves the term high-temperature insulation wool for man-made mineral wool suited to insulation above it, the range in which refractory ceramic fiber is used.
Ceramic Fiber FAQs#
Why Is a Glassy Fiber Called Ceramic?#
The first fibers were made by fusing calcined kaolin near 2000 °C, a ceramic raw material, so the name stuck although the fiber is a glass (ECFIA).
When Was Ceramic Fiber Developed?#
Ceramic fiber was developed in 1942 and became commercially available in 1953, according to the industry association ECFIA.