There are a number of options available in the process of dying fabrics and different kinds of dyes are used in the various processes. However one of the most effective and widely used dying processes is the one that is done using naphthols. The process of dyeing using naphthol is done in combination with insoluble azo dyestuffs. There is a complete cycle of steps that need to be followed in the dying process to be able to get the right results. The use of the naphthol dyes is most common for cotton fabrics apart from other cellulosic fibres such as jute, hemp, linen and even silk and rayon. The method and practice of dying using naphthols is most widely seen in African and wax prints. Understanding the process of dying using the combination of naphthols and azo dyes can help in establishing where the application is most suited.

How The Dying Process Works:

A component like the Naphthol AS-G is first broken up or dissolved after which it is applied on the fabric, which helps in exhaustion of the dissolved naphthol with the substrate. The excessive solution is then removed from the fabric. Removal of the solution is done either by squeezing it or by hydro-extraction using a machine or a device specially made for the purpose or by brine washing the surface for the removal of the solution. The naphthol component then goes through the diazotization process by the addition of the azo dye to components like the Naphthol ASITR. The entire solution of the azo dye and the naphthol is then treated or developed with the coupling of colour salts. Finally, the fabric is neutralized and soaped on boiling to remove extra pigment. The end result is then rinsed and dried to get a coloured and finished product.

Important Points To Be Noted:

While the method of dying fabrics using naphthols and azo dyes is popular among fabric manufacturers and textile businesses, there are a few things that need to be checked so that the process of dying does not go wrong. One of the most essential factors in dying with naphthols is to protect the surface from water spotting and fumes of acid, steam or chlorine along with protection from sunlight. It is also important to make sure that the temperature in the dying process is precise if the diazotization process needs to be effective. Another factor that helps in perfect dying of the fabric is to be careful about the hydro-extraction process. Applying too much hydro-extraction may lead to the developing of light spots on the surface of the fabric. Finally, it is important to ensure that enough amount of alkali agents are used and the fabric is rinsed immediately after the dying process is completed for the end result to be perfect.

While the processes and the post-processes of dying need to be followed closely, it is important to ensure that you have the right suppliers and manufacturers for the naphthols, naphthol AS-G and the naphthol ASITR that you use because the quality of the naphthol will dictate how the fabric is eventually dyed.