Union Dyeing | Union Dyeing Mixtures of Protein Fibers (Silk and Wool) and Cellulosic Fibers (Cotton)

Union Dyeing:
The advent of regenerated and synthetic man -made fibres has greatly increased the scope for making blends of two or more components. The oldest mixture of all is wool and cotton, which is used to make cloths known as unions. For this reason dyeing of mixtures of these two fibers is often referred to as union dyeing.

Ways of Union Dyeing:
There are three possible ways of union dyeing of protein and cellulosic fibers.Those are ---
  1. Dyeing the protein or cellulosic fibre and leaving the other white.
  2. Dyeing both fibres the same colour.
  3. Dyeing the two fibers different colour
Union Dyeing Mixtures of Protein and Cellulosic Fibers:

Dyeing the wool/silk fibres, leaving the cotton fibers white:
In this purpose generally acid dye is used to complete union dyeing process. Because, acid dye have no affinity of cotton fibers. So it is very easy to dyeing the wool/silk in union without staining the cellulose. For this process acetic or formic acid is use to instead of sulphuric acid to protect the cellulose. After dyeing the materials need to be washing well to remove the acid.
 
Union Dyeing
Dyeing the cotton fibres, leaving the wool/silk fibres white:
Direct dye is used for this dyeing process. Because at low temperature direct dyes will exhaust on the cellulose and at low temperature direct dye have no affinity of wool/silk. So it is best to dyeing cotton fibers, to leaving wool/silk white. In this process soda must be used, because it works as a protector for wool/silk fibres dyeing.

Dyeing the cotton and wool/silk fibres by different colour:
There are different process to dyeing the wool/silk and cotton fibres by using different dyes. In this process, firstly cotton fibres dyeing by direct dye at low temperature and than wool/silk fibres dyeing by acid dye. Finaly we get different colour union dyed materials.

Dyeing the cotton and wool/silk fibres by useing same colour:
In this purpose direct dye is used to complete union dyeing same colour. For this direct dye apply at high temperature and acidic medium. This process is very easy and cheap.

Union Dyeing Mixtures of Silk and Wool:
Silk and wool union dyeing process is partial difficult, because only without of temperature question both fibres have same affinity for dye. Silk is dyeing with acid and basic dye at low or medium temperature and wool is dyeing with acid and basic dye at high temperature.

Dyeing wool fibres ,leaving the silk white;
In this process acide dye is used and it apply on wool fiber at boiling temperature to produced color. In thsi process some color may be adjust on silk surface.But it can remove by treatment with ammoni aceted.

Dyeing silk fibres, leaving the wool white:
In this purpose, basic dye is used to complete union dyeing.Because basic colour have no affinity of wool at low temperature.So this process can be complete easily to apply basic colour on silk at low temperature.

Dyeing silk and wool fibres by useing different colour:

Firstiy wool fibre is dyeing by acid dye like as before process .Than ,remove colour from silk by useing ammoni aceted and dyeing silk fibres by basic dye at low temperature.

Dyeing silk and wool fibres by useing same colour:
It is very difficult process,because wool need to dyeing at boiling temperature and silk need to dyeing at low temperature to complete this union dyeing process. Generally acid dyes are used for this process.

Conclusion:
Different fibres can be used to union dyeing. I only give some basic knowledge about it. This dyeing process need to be done very carefully because, mistake of some thing can damaged the materials.
 
 
Author of This Article:

Shareful Islam Palash
Uttara Engineering College, Uttara, Dhaka
Email: palash313@gmail.com
Facebook: Palash






 
Shareful Islam Palash
Uttara Engineering College, Uttara, Dhaka
Email: palash313@gmail.com
Facebook:www.facebook.com/sharefulislam.palash - See more at: http://textilelearner.blogspot.com/2013/02/what-is-organdy-finishing-cotton.html#sthash.cvs27zX2.dpuf

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