Dyes and Tans. 



224 



[March, 1909. 



the latter drop is due rather to the in- 

 troduction of cheaper substitutes, and 

 to the extensive adulteration which 

 took place some years ago. Cuteh is 

 now used chiefly for curing or pre- 

 serving fishing nets, and sails, the ob- 

 ject of ditching nets being to prevent 

 them from heating, and if they do 

 heat, to prevent the heat from rotting 

 the fabric. Dyers have almost entirely 

 discarded cutch for aniline substitutes. 



(2) Substitutes for cutch. — The chief 

 products which have severely competed 

 with Burma cutch are mangrove cuich 

 from Borneo and elsewhere, and aniline 

 dyes. 



Mangrove cutch. — It is believed to be 

 some twenty years since mangrove cutch 

 was first introduced to the fishing in- 

 dustry in Great Britain, but it was not 

 till 1898, as the result of very extensive 

 advertising, that it was used to any 

 great extent. It has also gained a foot- 

 ing in Holland during the past few years, 

 but is not very largely used. Few 

 fishermen use mangrove cutch alone ; 

 some will not use it at all, while others 

 use a proportion mixed with Burma 

 cutch. Mangrove cutch is obtained at a 

 considerably lower price than Burma 

 cutch, and is less liable to fluctuations 

 in price. Although as a preserving 

 material for fishing nets it is inferior to 

 Burma cutch, still it finds favour to 

 some extent because it dissolves readily 

 and gives a red solution without any 

 residue. As mangrove cutch does part 

 of the work for which Burma cutch is 

 used, it affects principally the cheaper 

 qualities of the latter, and lessens the 

 consumption of the cheaper grades of 

 Burma cutch. For this reason it is 

 most advisable to keep the standard of 

 Burma cutch at the highest possible 

 level- Mangrove cutch is manufactured 

 from the bark of mangroves, the chief of 

 which are Ceriops Candolleana and 

 Rhizophora spp. The trade in this cutch 

 in the Straits is an extensive one, the 

 amount passing through Singapore 

 alone being over 20,000 cwt. annually. 

 The imports into Singapore are from 

 Borneo, Labuan, Sarawak and other 

 localities, not from the Federated Malay 

 States, whilst the imports into Penang 

 are mostly from Sumatra. A large 

 proportion of the mangrove cutch 

 imported into Singapore is used locally 

 and not exported. 



The Divisional Forest Officer, Rangoon 

 Division, reports a local manufacture ot 

 mangrove extract which is not exported 

 but is used locally for curing fishing 

 nets and sails; a similar extract is pre- 

 pared in Arakan. 



Analysis of mangrove cutch. — A sample 

 of mangrove cutch received from the 



Straits was subjected tc analysis by 

 Mr. Puran Singh, Acting Imperial Forest 

 Chemist, who reports on it as follows : — 



"The sample of mangrove cutch shows 

 little resemblance with cutches of Acacia 

 and Gambier. It does not answer the 

 general tests for cutches. It is entirely 

 soluble in cold water, while good cutch 

 is almost entirely insoluble in cold 

 water. It has no crystalline principle 

 like catechin and appears to be a sort of 

 tannic acid which in dilute solutions 

 gives a very dirty green colour with a 

 dilute solution of ferric chloride, while 

 catechu-tannin gives in dilute solutions 

 a fine green colour. It has been tried by 

 Messrs. R. B. Brown and Hummel for 

 dyeing, and they report on it favourable 

 as a dyeing agent. 1 cull the following 

 lemarks from the reports of the Im- 

 perial Institute, London, for the year 

 1903:- 



" 'The Mangrove Cutch behaved during 

 the dyeing process very similarly to 

 theBull-cutch, the chief difference being 

 that in the first operation the cotton is 

 stained a very much more reddish-shade 

 than that given by any other cutch 

 examined. These dyeing experiments 

 show that the Bull and the Mangrove 

 cutches may be considered as belonging 

 to group II, indeed they may be placed at 

 the head of this class, since after twice 

 dyeing they give much darker colours 

 than any of the rest-' 



"As a tanning agent it is not so favour- 

 able as it produces very inferior leather 

 of red colour. However, it is very much 

 recommended for producing sole leather 

 as the latter tanned by it is com- 

 paratively more tight and durable." 



Aniline rfa/es, -Dyers have now almost 

 ceased using cutch in favour of aniline 

 colours, and it is only the continued 

 development of the fishing industry 

 which has saved the cutch trade from 

 extinction. The following extract, from 

 the journal of* the Society of Chemical 

 Industry, affords information on the 

 subject :— 



" Catechu ; Substitutes for—, and their 

 application in Calico Printing. G. 

 Grieder, Farber Zeit. 1901, 12, (1), 7—9. 

 Catechu, which was formerly largely 

 employed in dyeing and printing of cot- 

 ton fabrics, has been largely replaced 

 in the former industry by these sub- 

 stantive colours, which acquire the 

 requisite fastness by an after treatment 

 with metallic salts, or by coupling with 

 diazotised paranitraniline. In calico 

 printing it has been superseded by 

 alizarins or other colours which are 

 fixed by metallic oxides on steaming. 

 In the printing of hosiery fabrics, such 

 as flannelette, it is still employed to 



