TEXTILES 237 



their location may be seen in the fiber. Thin sections are preferable 

 (especially for photomicrographs) because of the limited depth of field 

 of the oil immersion objective. Irregularities and marks on the surfaces 

 of the libers may also be observed. 



For the more birefringent synthetic fibers the high bright contrast 

 (0.07A+0.25X) usually shows more detail than does the A— or B — 

 diffraction plates. By a proper choice of phase and mounting medium 

 it is possible to examine the details of the fiber, including any surface 

 patterns present. Refractive indices of some textile fibers are given in 

 Table Y.IB. Special mounting media have been devised by Bradfoot 

 and Schwartz (1948) for textile microscopy (see also Table IV. 1). 



Few^er papers have been published in the industrial field, probably 

 because publication usually is deferred until the product has been 

 marketed. More applications may be expected with more general 

 application of the phase microscope. The discussion in this chapter 

 points the way. 



