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Vat dyeing machine - Yarn dyeing in open beck

Machines used for Vat dyeing

The vat dyeing process can be done in two types of machines, and according to this vat dyeing process can be divided into two following methods.
(A)  Dyeing of yarn in an open beck

(B)  Standfast molten metal process

Explanation -

(A) Dyeing of yarn in an open beck:

The yarn may be dyed using this procedure, which is the earliest and easiest. 

Unbent or straight rods (or sticks) long enough to span the width of the tank are employed in the procedure, which takes the shape of an open rectangular tank. 

On the rods that typically support 1 kg of 1 anks each, the hanks are hanged. 

Two workers, who are on opposing sides of the beck, handle the rods as they're being dyed. 

With the help of a straight rod that the workers skilfully handle, the hanks are physically twisted around. 

As a result, the parts of every rod's hanks that are exposed to the air are each submerged within the alcohol once. 

Vat dyeing machine - Yarn dyeing in open beck

The yarn hanks are rotated around on each pole at regular intervals to use dye. 

It is recommended to rotate the hanks as often as possible. 

Using bent rods guarantees even colouring since it keeps the fabric completely submerged during the entire dying procedure. 

As may be seen in the Figure below, a bent rod with hanks hung from it submerged within the dye bath. 

The twisting of the fabric does present some challenges, though. additionally, the hanks occasionally have a bent to float within the dye bath if the yarn has not been well-scoured, which makes manual handling challenging. 

Open-beck method for vat dyeing
Open-beck method

Steam, coal, or wood can all be accustomed to heating the tank. The open-beck method entails subsequent precautions to provide consistent dyeing.

(i)The object should be forcefully agitated during the dyeing process, especially in the beginning, to make sure that the whole object makes uniform contact with the dye fluid. 

(ii) All of the hank rods that are being dyed are withdrawn and placed at one end of the tank during additions, exposing the material to the air. Hydros and sodium hydroxide have to be added frequently to resolve this issue. 

(iii) The dyer should have a correct knowledge of the properties of dyes, especially the rates of dyeing of vat dyes.

(iv) to confirm level dyeing, it's crucial to keep up the liquor ratio and dyeing temperature in addition to the presence of sodium hydroxide and hydros.   

(v) Careful consideration should run to the dyes chosen for creating mixed hues, and whenever possible, dyes from the identical family should be chosen. 

Separating each component dye in an exceeding vat is often advantageous. 

(vi) due to the disparities in fastness characteristics and therefore the various speeds of dyeing, it's best to avoid combining blue and yellow and yellow and green.

Questions -

  1. Which types of machines are used for the Vat dyeing process?
  2. Explain the vat dyeing of yarn in an open beck.


Hussain, T. (2007, November 19). Important considerations in dyeing with vat dyes.; Fibre2Fashion.

Kim, M. R., Kim, H., & Lee, J. J. (2013). Dyeing and fastness properties of vat dyes on meta-aramid woven fabric. Fibers and Polymers14(12), 2038–2044.

Patwary, E. M. Z. (2012, May 4). What is vat dye. Textile Fashion Study; Engr. Mohammad Zillane Patwary.

Saha, S. (2018, October 21). Vat Dyes. Blogger.

Sharmin, F. (2017, November 18). Dyeing of cotton with vat dye. Textile Study Center.

The Editors of Encyclopedia Britannica. (2015). vat dye. In Encyclopedia Britannica.

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 - Rushikesh Patil (Textile Engineer)
(DKTE Society textile engineering college Ichalkaranji)
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