OCR Text |
Show Why Rosin in Paper Rosin Is used in the manufacture of paper to make It "water resistant" io that It will be resistant to writing lnt For this purpose common rosin li treated with soda, a rosin soap being formed which Is a combination of to. dlum reslnate and free rosin and which. Is soluble In water. This material li added to the paper stock in the torn of a dilute solution In water, Ain. mlnum sulphate is then added to the paper stock, this precipitating therosla In very finely divided form, the precipitate pre-cipitate consisting of a mixture of aluminum- reslnate and free resin which, when the paper sheet Is dried, forms a water-proof film over the piper pi-per fiber. |