346 The N.Z. Journal of Science and Technology. [Nov. 
THE GENUS COPROSMA AS A SOURCE OF DYES. 
(Continued from page 267.) 
By B. C. Aston, F.I.C., Chemist to the Department of Agriculture. 
In this preliminary article all the author hopes to accomplish is to draw 
attention to an extremely technical subject, which will require con¬ 
siderable further experimental work on a larger scale than is possible in 
the laboratory before much may be said of the application of coprosma 
dyes in industry. 
There is at present a strong movement in New Zealand towards the 
establishment of home spinneries, and the desire is that not only the 
fabrics but also the dyes may be home-made. No one who has once 
worn homespun tweeds would for comfort wish for anything better, 
and it is hoped that New Zealand homespuns made by returned 
soldiers from wool and dyes grown in this country may become as 
fashionable and command as good a price as the celebrated Harris tweeds 
of fragrant memory. 
It would seem that the conditions for home-dyeing woollen goods in 
New Zealand, compared with those in North Britain, are particularly 
favourable. In every district is to be found one or more of the species 
of Coprosma suitable as a source of dyes, for these belong to the poly- 
genetic class and yield fast colours which vary greatly with the mordant 
employed (see Table B). Thus Coprosma grandifolia, which is par excellence 
the dye-plant of New Zealand, is abundant from the Three Kings and the 
North Cape to Marlborough and the south-west of Nelson Province, and 
ranges from sea-level to 2,500 ft. In the more southerly part of the South 
Island, where this species cannot be found, very effective fast colours may 
be obtained from Coprosma lucida— the karamu of the Maori—which is 
abundant throughout the Dominion, ascending from sea-level to 3,200 ft., 
or from Coprosma areolata, which is not uncommon in lowland forests 
throughout, occurring from sea-level to 1,500 ft. This last species will 
also be of value in furnishing a most useful direct or substantive dye which 
may be applied without any mordant, and will leave the wool, after 
dyeing it a full brown, in a beautifully soft condition. It is almost certain 
that several other species of Coprosma will furnish fast dyes on wool 
suitably mordanted — Coprosma rotundifolia and C. rhamnoides, for 
instance, have proved recently to be satisfactory in this respect. 
If the coprosma prove inadequate to supply all the necessary colours 
required in the suggested home dyeing there is an unexplored field which 
will probably prove fertile in dyes in the New Zealand lichens, several of 
which are identical with those used for wool-dyeing in Scotland.* Lichens 
have the advantage that they yield direct wool-dyes, the use of mordants 
being unnecessary. Then there is the weld ( Reseda luteola ). not uncommon 
as an imported weed in this country, which Knechtt considers superior 
to all natural yellow colouring-matters in regard to fastness to light, and 
certainly inferior to none in regard to fastness of milling. There are 
* Journ . Agr ., vol. 15, p. 128, Wellington, 1917. 
f Manual of Dyeing , p. 355, 1917. 
