Overdyeing and tinting:
In tinting procedure, the garment is lightly coloured to give the final denim appearance a slight shift. Tinting of denim garments is usually done after the stone wash process. This is not true overdyeing but merely gives the impression of a change in the overall colour of the fabric. This process consumes a large quantity of water and chemicals. To make this process economical and ecologically friendly, some novel colour-based enzymes were introduced to the market. Using this technique, tinting and stone washing effects can be achieved in a single bath.
Advantages are:
Overdyeing or tinting of denim is an additional dyeing treatment normally carried out on jeans after they are sewn. This adds another colour to the jeans. Normally denim garments are overdyed with yellowish dye to appear dirty.
Denim garment tinting is normally carried out after the stonewash process. During tinting, a small amount of tint or colour is added to the garment to change the hue, cast or tone of indigo shade. However when the quantity of tint colour is increased, it covers up the indigo.
Various types of dyes are used for overdyeing and tinting:
Advantages of the technique are that:
As a result of fading tests involving sandblasting, laser and washing, the strength and weight values of fabrics decreased depending on the increase in pressure in sandblasting, the burning intensity of the laser, and the increase duration and number of washings.
Significant colour loss was observed in fabric colour in line with the increase in these parameters. Back-staining values obtained from washings increased in desizing and other washing processes. However they decreased and were not even observed in bleaching and laccase enzyme washings and the colour of pocketing moved toward a yellow shade.
Significant losses were observed in the strength and weight of the fabric as a result of physical fading methods involving laser and sandblasting. To decrease these losses in production conditions, physical wear must be applied to the lowest degree. The required colour loss effect must be obtained later by regional bleaching to be directed to the area that is to be worn out physically.
On the other hand, to prevent strength and weight losses after hypochlorite washing, the pH of bleaching liquor must be around 11–12, at which hypochlorite least damages the cotton, or the required colour must be obtained by alternative bleaching processes (eco-bleach, laccase, organic peroxide, etc.). Certainly, the selection of these processes is not easy because of the required colour shade.
Back staining, which is one of the most important problems in denim washing, can be removed with the aid of laccase washing applied after normal washings for a short time and at a low concentration, because it fairly lessens after laccase washing, as seen from the results of these trials.
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In tinting procedure, the garment is lightly coloured to give the final denim appearance a slight shift. Tinting of denim garments is usually done after the stone wash process. This is not true overdyeing but merely gives the impression of a change in the overall colour of the fabric. This process consumes a large quantity of water and chemicals. To make this process economical and ecologically friendly, some novel colour-based enzymes were introduced to the market. Using this technique, tinting and stone washing effects can be achieved in a single bath.
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| Fig: Effect of Tinting on denim garments (Image courtesy: https://denimsomething.com/) |
- Less process time to achieve a tinted look
- No extra chemicals are required, which makes the process more economical
- Less water consumption
- Less energy consumption
- Less chance of patchiness or unevenness
Overdyeing or tinting of denim is an additional dyeing treatment normally carried out on jeans after they are sewn. This adds another colour to the jeans. Normally denim garments are overdyed with yellowish dye to appear dirty.
Denim garment tinting is normally carried out after the stonewash process. During tinting, a small amount of tint or colour is added to the garment to change the hue, cast or tone of indigo shade. However when the quantity of tint colour is increased, it covers up the indigo.
Various types of dyes are used for overdyeing and tinting:
- Direct dyes
- Reactive dyes
- Pigment colours
- Sulphur dyes
Advantages of the technique are that:
- It consumes less water and energy and takes less process time to achieve a tinted look.
- No extra chemical is used in this process.
- The chances of patchiness or unevenness in the garment are almost zero.
As a result of fading tests involving sandblasting, laser and washing, the strength and weight values of fabrics decreased depending on the increase in pressure in sandblasting, the burning intensity of the laser, and the increase duration and number of washings.
Significant colour loss was observed in fabric colour in line with the increase in these parameters. Back-staining values obtained from washings increased in desizing and other washing processes. However they decreased and were not even observed in bleaching and laccase enzyme washings and the colour of pocketing moved toward a yellow shade.
Significant losses were observed in the strength and weight of the fabric as a result of physical fading methods involving laser and sandblasting. To decrease these losses in production conditions, physical wear must be applied to the lowest degree. The required colour loss effect must be obtained later by regional bleaching to be directed to the area that is to be worn out physically.
On the other hand, to prevent strength and weight losses after hypochlorite washing, the pH of bleaching liquor must be around 11–12, at which hypochlorite least damages the cotton, or the required colour must be obtained by alternative bleaching processes (eco-bleach, laccase, organic peroxide, etc.). Certainly, the selection of these processes is not easy because of the required colour shade.
Back staining, which is one of the most important problems in denim washing, can be removed with the aid of laccase washing applied after normal washings for a short time and at a low concentration, because it fairly lessens after laccase washing, as seen from the results of these trials.
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