Strong of its experiment, the Société Commerciale Raoul-Duval draws from the know-how and the files of the Compagnie Fran?aise des Extraits of which it is heiress in order to update the use of the natural dyes in textile industry.
Of course we do not want to substitute for synthetic dyes, because vegetable resources from where come our different dyestuffs have to be respected and exploited under strict control. Our aim is to propose natural dyes, which are not toxic, and which can be used on every natural textile support: wool, silk, cotton, flax, but also jute, ramie, etc.
All natural dyestuffs, except for indigo, are mordant dyes, it means that they require the utilisation of a mordant which makes the link between the textile fibre and the natural dyestuff. Used with different mordants, a natural dye will give various colours, thus it is very important to weel select the mordant.
Mordants are metallic salts.
The most comonly used are:
Alum ( amuminium potassium sulphate) - for bright colours
Aluminium sulphate - for bright colours
Ferrous sulphate (Fe 3) - for dark colours
Copper sulphate in mixture with one of both aluminium and ferrous mordants - in order to increase lightfastness
OTP - for yellow/orange/brown colours
Potassium dichromate - for balck shafes - this product is very dangerous for environment
The indigo, unmatchable blue source, is the only natural dye which is a vat dye, consequently it does not require the utilisation of a mordant. Used under its soluble form (leuco derivate), it will have to be unsolubilised into the fibre by reduction.
France
