cooking diluting fluid is constituted by a filtrate from a subsequent stage in which more calcium has been released from the wood calcium in the wood otherwise constitutes a problem in the manufacture since calcium causes deposits known as u201c scale u201d on the process equipment these deposits are difficult to dissolve fig1 makes it clear that in order to take advantage of a high ionic strength which is advantageous for the deposition of cmc onto the fibres it is an advantage if the cmc is present either during at least the initial phase of the cooking stage and or in association with the termination of the cooking process or in subsequent alkali treatment stages these subsequent alkali treatment stages which release calcium from the wood raw material may for example be constituted by a subsequent oxygen gas delignification in one or several stages a temperature of approximately 130 160 u00b0 c is established during the cooking stage and this high temperature is also advantageous for the deposition of cmc onto the fibres a somewhat lower temperature in the region of 100 140 u00b0 c is often established during the input to the cooking stage but this is compensated to a certain extent by the additive effect of the batchwise addition of white liquor which creates a very high ionic strength something that is obtained not only from the presence of na ions but also from that of ca 2 ions a high degree of deposition of cellulose derivative principally takes place during the latter part of the cooking stage or in association with subsequent alkali treatment stages most often oxygen gas delignification in which.