Colouring of Paper-pulp Red or Rose-Colour

Practical Magazine 16, 1876

(Chemistry applied to the Arts, Manufactures, &c. Miscellaneous).

In the colouring of paper-pulp it is difficult to obtain a dark tint or one of bold tone, like red and rose-colour. The following is a method of obtaining a beautiful pure red or rose-colour:

When a decoction is made, much charged with Pernambuco, Brazil, or other red wood, it ought not to be stirred in the refining basin at the same time that the glueing takes place. A quantity of the decoction of red wood, proportioned to the shade desired, is poured into the basin. On the other hand, there is poured on to the resinous soap chloride of tin, which has the property of forming a precipitate of colophony or resin, and which is afterwards poured into the basin, care being taken to stir as much as possible while it is being poured, until the pulp has taken the required tone of colour. The pulp may then be transferred to the tubs of the paper-making machine. The chloride of tin should be diluted in ten times its weight of water before being mixed with the resinous soap. The shade of red or rose-colour varies with the quantity of tin that is employed, and this chloride is obtained by mixing ten parts of nitric acid with twenty of hydrochloric acid, in which all the tin is to be absorbed until the mixture is dissolved. The tin should be brought to thin flakes before being employed, for which purpose it is fused and poured into cold water. About 9 lbs. of tin are required for the above quantities of acids. In this process it is not necessary to use alum or sulphate of alumina.

- Le Teinturier Practique.

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