Sentence:  Mounting with Lakeside-70 thermoplastic cement was used extensively but it was too brittle, caused occasional plucking of sand grains during grinding and polishing, and was not strong enough to hold the mounted specimen during <WSD>resectioning</WSD>; its thermoplastic requirements caused warping of specimens. 
Meaning of the word marked with <WSD> tags:  To thinly slice a specimen as part of its preparation, such as when preparing a microscope slide.