page_title: Glass-ceramic
section_title: Cooktops
hierarchical_section_title: Glass-ceramic / Cooktops
context_page_description: Glass-ceramics are polycrystalline materials produced through controlled crystallization of base glass. Glass-ceramic materials share many properties with both glasses and ceramics. Glass-ceramics have an amorphous phase and one or more crystalline phases and are produced by a so-called "controlled crystallization" in contrast to a spontaneous crystallization, which is usually not wanted in glass manufacturing. Glass-ceramics have the fabrication advantage of glass, as well as special properties of ceramics. When used for sealing, some glass-ceramics do not require brazing but can withstand brazing temperatures up to 700 °C. Glass-ceramics usually have between 30% [m/m] and 90% [m/m] crystallinity and yield an array of materials with interesting properties like zero porosity, high strength, toughness, translucency or opacity, pigmentation, opalescence, low or even negative thermal expansion, high temperature stability, fluorescence, machinability, ferromagnetism, resorbability or high chemical durability, biocompatibility, bioactivity, ion conductivity, superconductivity, isolation capabilities, low dielectric constant and loss, high resistivity and break-down voltage.
context_section_description: Glass-ceramic from the LAS-System is a mechanically strong material and can sustain repeated and quick temperature changes. However, it is not totally unbreakable.  Because it is still a brittle material as glass and ceramics are, it can be broken. There have been instances where users reported damage to their cooktops when the surface was struck with a hard or blunt object (such as a can falling from above or other heavy items).
  The material has a very low heat conduction coefficient, which means that it stays cool outside the cooking area. It can be made nearly transparent (15–20% loss in a typical cooktop) for radiation in the infrared wavelengths.
  In the visible range glass-ceramics can be transparent, translucent or opaque and even colored by coloring agents.
  Today, there are two major types of electrical stoves with cooktops made of glass-ceramic:
  A glass-ceramic stove uses radiant heating coils or infrared halogen lamps as the heating elements. The surface of the glass-ceramic cooktop above the burner heats up, but the adjacent surface remains cool because of the low heat conduction coefficient of the material.
  An induction stove heats a metal pot's bottom directly through electromagnetic induction.
  This technology is not entirely new, as glass-ceramic ranges were first introduced in the 1970s using Corningware tops instead of the more durable material used today.  These first generation smoothtops were problematic and could only be used with flat-bottomed cookware as the heating was primarily conductive rather than radiative.
  Compared to conventional kitchen stoves, glass-ceramic cooktops are relatively simple to clean, due to their flat surface. However, glass-ceramic cooktops can be scratched very easily, so care must be taken not to slide the cooking pans over the surface. If food with a high sugar content (such as jam) spills, it should never be allowed to dry on the surface, otherwise damage will occur.
  For best results and maximum heat transfer, all cookware should be flat-bottomed and matched to the same size as the burner zone.
caption: A glass-ceramic cooktop
exif: {"Image Make": "", "Image Model": "4MDSC", "Image Software": "1.00{B0648}", "Image ExifOffset": "106", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail JPEGInterchangeFormat": "796", "Thumbnail JPEGInterchangeFormatLength": "5925", "EXIF ExposureTime": "10/313", "EXIF FNumber": "287/100", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0210", "EXIF DateTimeOriginal": "2005/12/29 14:01:35", "EXIF DateTimeDigitized": "2005/12/29 14:01:35", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "2", "EXIF ShutterSpeedValue": "49/10", "EXIF ApertureValue": "3", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "6", "EXIF MeteringMode": "MultiSpot", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash fired", "EXIF FocalLength": "41/5", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2720", "EXIF ExifImageLength": "2040", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "0100", "EXIF InteroperabilityOffset": "724"}