Plugged in and turned on. All paper. All the time.
This semester I enrolled in an introductory pulping and bleaching course. Historically the lab part of the course walked students through the pulping and bleaching sequence using wood chips. Thanks to a donation to the college of locally grown flax fiber we got to experiment a bit.
Fibers from flax used in paper making (and in making linen cloth) are bast fibers, found in the stems of the plant. These cellulose fibers are long and strong. Cooking the fibers in strong alkaline solution you can start to separate the desired cellulose from the undesired lignin.
We loaded the batch digester with pre-soaked flax and charged it with our sodium hydroxide (NaOH) solution based on cooking parameters calculated in lab. If the calculations were off, the alkali could be consumed and the lignin deposited back on the fiber. This condition is forebodingly termed the ‘dangerous cooking crest.’
Four hours later and the fiber was done. We were expecting it to take 2.5 hours but the best laid plans. . . a safety valve on the steam delivery system broke and we had to stop the cook to make repairs. The fiber is rinsed and waiting in the cooler for next week’s lab now. We’ll see what kind of lignin content we are left with!