Pretreatment Process Cracking in Wool Products
- Created on Tuesday, 29 January 2019 22:29
- Last Update: Wednesday, 02 February 2022 17:53
- Published on Tuesday, 29 January 2019 22:29.
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Fractures that may occur in the fabric during the finishing processes with woolen fabrics are very important. Cracking (boiling) is done in order to prevent these fractures beforehand and to fix the fractures that occur.
Crabbing can be done on raw fabrics and treated fabrics.
In crabbing made on raw fabrics, the tensions in the fabric are removed and the dimensions are fixed, in a sense, the fabric is fixed beforehand.
In treated fabrics, both broken and creases are corrected and the fabric dimensions are fixed.
Factors Affecting Cracking
Cracking is usually done when the crabbing bath is around 95 °C. However, the temperature should vary depending on the characteristics of the gripped fabric.
For colored and unwashed fabrics, the curing temperature should be kept relatively low.
It should also be high on white and washed fabrics.
There is a risk of dyeing on colored fabrics when high temperatures are reached.
In unwashed fabrics, it is possible that dirt and oils penetrate the fabric by cooking, making it difficult to clean in subsequent washings.
Since these hazards are not present in white and washed fabrics, higher temperatures increase the curing effect and ensure that the process is suitable for its purpose.
For a good charring, colored and unwashed products are charred at 30-50 °C for about 2 minutes, and for white and washed products at 95 °C for about 2 minutes.
Cracking is best done in a neutral or slightly alkaline environment.
However, it is necessary to add an anti-cracking agent to the charring liquor to prevent creping that may occur during charring.
The fabric, which passes over the main drum with the conveyor belt in the Krab machine, encounters a pressure here.
In addition, the pressure of the windings is also in question in the discontinuous crabbing.
In both methods, the smoothness of the pressure to be applied on the fabric will directly affect the smoothness of the fixation.
The pressure differences that will occur will make the fixation different and cause errors that are difficult to correct in later processes.
It is necessary to fix the form gained by the clad fabric with a sudden cooling.
However, in special fabrics (pool table cloth) it is asked to cool slowly by wrapping it in a wooden cylinder.
Shock cooling is done by immersion in cold water or by running through a cold cylinder.
Features that Cracking Brings to the Product
Crabbing process is based on the principle of cooling the woolen fabrics after being treated with hot water.
The fibers swell and gain volume in the woolen fabric that encounters hot water.
With this voluminous state, the fabric gains a softer and fuller handle.
This change in fabric handle also enables the fabric to gain a smoother surface.
Due to this smoothness, the fabric gains a brighter appearance.
Unwashed and non-rested fabrics that have a high risk of breakage during washing and wet processes should definitely be crammed.
Since the deformation request of the fabric is minimized during creasing, breakage and wrinkling that may occur during washing and dink are also minimized.
Cracking can also be done on fabrics that have been washed, rested and have undergone other wet treatments to remove the cracks and wrinkles that have occurred during the processes.
The fabric, which has been loosened with hot water, becomes smooth by encountering the pressure in the krabbing machine appropriately, and this smoothness is made permanent by the cooling done right after.
Since the felting feature of the fabric will decrease during crabbing, the fabrics that will be rested in high percentages should be rested before cracking.
Otherwise, it will not be possible to listen at the desired intensity.