Electrical properties determine how much noise the glass is likely to produce in recording situations. The lower the product of dielectric constant times the loss factor, the smaller the equivalent noise current the glass will produce （Rae and levis, Methods in Enzymology, 207, p67, 1992）. Patch clamp glass with good electrical properties is critical especially in single-channei recording.

Sealability: It is not clear what factors determine the sealing ability of the patch to the glass. Almost any glass can form a gigohm seal under the right conditions. Different glass types very, however, in how easily they form a seal. It is important to select a patch clamp glass that seals easily. Good fire polish is critical for seal （see DMF1000）.

Leachable components: Substances leached from glass can alter channel behavior. Since different channels are sensitive to different glass components, it is best to record one type of channel with several different kinds of pipette glass to eliminate any artifact due to the glass.  WPI offers capillary tubing made from two glass types widely used in constructing patch clamp electrodes. The significant characteristics of each are as follows:

PG52151-4, PG52152-4 and PG52165-4 are prepared from Schott#8250 glass （equivalent to Corning #7052）,one of the most widey used patch clamping glasses. This is a specially formulated borosilicate glass with a softening temperature that is 110°C lower than regular borosilicate glass （Corning 7740, or Pyrex）. It has excellent sealing properties for most cells. Electrical properties are also very good.

PG10150-4 and PG10165-4 are composed of Corning #0010 glass, a high lead content （22%PbO）glass. lts thermal and electrical performance is between the Schott #8250 and Corning #8161 glasses described above. It is much more economical than Corning #8161 glass. It has been found that this glass causes much less alteration in channel behavior than Corning #8161 and Schott #8250 glass （Furman and Tanka, Biophys. J. 53, p287, 1988）.

Patch clamp capillaries do not have microfilaments.