Knittel Coverglass

Created by Karen Darley, Modified on Fri, 3 May at 1:48 PM by Kathleen Patrick

KNITTEL Coverglass is made of a colourless borosilicate glass (D 263) with an optimum hydrolytic resistance HGB1. This ultra thin glass is produced by only two special glass companies worldwide and by patented down?draw?technology working with very expensive platinum orifices for getting blister and striae-free glass. The "ultra-thin glass foils" are regularly checked by the Quality Control Systems of our supplier to ensure accurate chemical composition and glass thickness.

Through our consistent developments and automatisation of the process and cutting technology, we have reached the optimum dimensional accuracy. Our coverglass is manufactured in accordance of the international standard ISO 8255/1 and is ready to use.

D 263 M cover glass is a colourless borosilicate glass with a very low iron content. Its composition assures excellent resistance to chemical attack. D 263 M meets the requirements laid down in ISO 8255/1.

The outstanding features of D 263 M include:

  • Virtually colourless appearance
  • Excellent internal glass quality with very low levels of inclusions, striae, bubbles, streaks, etc.
  • High spectral transmission
  • Exceptional cutting and grinding characteristics
  • Excellent flatness
  • Optimum resistance to chemical attack
  • Refractive index finely adapted to microscopes
    D 263 M is used as coverglass in microscopy for medical, biological and research work.
    Spectral transmittance (d=0.15 mm)
  • Transformation temperature is 557°C


Between 0.15 und 0.40 mm glass thicknesses, the light transmittance is ôVA = 91.8%. In the visible range of the spectrum D 263 M is without absorption. The excellent UV absorption properties makes D 263 M an ideal material for use in fluorescence microscopy.

Optical properties:

Refractive indices (directive values)
ne (ë = 546.1 nm): 1.5255 ± 0.0015
nD (ë = 589.3 nm): 1.5230
Abbe value íe : 55

Chemical properties:

Hydrolytic class: HGB 1 (DIN?ISO 719)

Thermal properties:

Transformation temperature Tg in °C 557 (straining point: 529°C)

EC Declaration of Conformity

We herewith declare that the products

Coverglass, water-white glass of hydrolytic class 1, precise cutting, in accordance with ISO 8255/1

Microscope slides, sodalime glass, cleanly washed and polished, in accordance with ISO 8037/1
are in conformity with the provisions of the following EC Directive:
European Guideline 98/79 EG for in vitro diagnostics dated 27th October 1998


Other thicknesses are available upon request. All data are subject to change.

  1. The accuracy of measurement for the thickness is ±5µm
  2. For trimmed glass (without the bead), flatness is measured net width x length. The maximum deviation of the height at any point on the total surface of the glass panel is measured from an ideal plane surface. The determined maximum value is the index for the flatness deviation. It does not, however, include the nominal thickness of the glass panel.

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