Disadvantages of Sulphur dyes
(i) Bronziness of shades and
(ii) Tendering of sulphur black dyed goods.
Explanation -
Bronziness of shades :
Particularly with sulphur black, this is often one of the frequent mistakes. Bronziness has many alternative root causes, several of which are given below.
The following are the causes:-
(1) long interval between removing the fabric from the dye bath and washing it off. i.e Prolonged drying times following the removal of things from the dye bath or the draining of the dye liquid
(3) Common salts are used excessively as depleting substances.
Because of this, the dye is only partially reduced.
(4) Dyestuff is present on the material as a result of dyeing in a very potent bath(strong bath)
(5) When there's not enough sodium sulphide available during the dyeing process, the dyestuff doesn't completely dissolve, and dye builds informed the surface of the fabric being dyed. I.e lack of reducing agent, or Na2S, in the dye bath.
This causes bronziness because the superficial dye is quickly converted to an insoluble form on the surface.
Solutions for Bronziness:
If bronziness persists despite these measures, it should be alleviated by any of the subsequent remedies.
(ii) in an exceedingly second procedure, the things are exposed to liquid ammonia (2 ml/l) and 2-3 g/l TRO for 30–45 minutes at 40–50°C.
Recipe | |
(1) Liquor Ammonia (3)Time | 2 ml/l |
(iii) By soaking the dyed cloth in an exceedingly hot soap solution for long enough, the bronziness also can be eliminated.
(iv) Bronziness may be eliminated by treating coloured goods with vegetable oil emulsions containing soda. Without washing the products, hydro-extraction and drying are performed.
Tendering of Sulphur black dyed goods
- Sulphur black-coloured cotton products have the foremost problem of degrading during extended storage.
- The material strength decreases as a result of the degradation or tendering.
- Free oil of vitriol has been discovered to be present within the deteriorated material.
- Free sulphur within the products is believed to be the reason behind the creation of acid since it reacts with moisture within the air to get the oil of vitriol.
- The cellulose is hydrolyzed by the acid, which causes material deterioration.
- It has been noted that the presence of iron within the coloured material hastens both the cellulose's breakdown and therefore the dye's disintegration.
- From the sodium sulphide utilized in dyeing, iron as an impurity is often obtained.
- Additionally, it's been discovered that after being post-treated with cupric sulfate, cotton fabric that has been coloured with sulphur black includes a greater propensity to be tendered.
- The risk of tendering during storage is often decreased by treating the dyed material with potassium or sodium bichromate, followed by rinsing.
- Sulfur that's free and active is oxidised, and also the byproducts of that oxidation are eliminated before storage.
- As a backup plan, the treated items can alternatively be dried without washing or rinsing and given an alkaline finish (using soda or other mild alkalies like sodium acetate or trisodium phosphate).
- during this scenario, the alkali present within the dyed material will neutralise any acid created during storage.
Questions -
- What are the disadvantages of sulphur dyes?
- Which Solutions are used for Bronziness during the sulphur dyeing process?
- Describe Tendering of Sulphur black dyed goods.
References
Abhishek. (2019, September 13). Sulphur dyeing process, dyeing of cotton with sulphur dye. Chemwhite.com; Abhishek tiwari. https://chemwhite.com/exllent-information-of-sulphur-dyeing/
Chakraborty, J. N. (2011). Sulphur dyes. In M. Clark (Ed.), Handbook of Textile and Industrial Dyeing (Vol. 1, pp. 466–485). Elsevier.
Orton, D. G. (1974). SULFUR DYES. In The Chemistry of Synthetic Dyes (pp. 1–34). Elsevier.
Patwary, E. M. Z. (2012, May 3). Properties, types, and uses of sulphur dye. Textile Fashion Study; Engr. Mohammad Zillane Patwary. https://textilefashionstudy.com/sulphur-dyes-properties-types-uses/
Sayed, A. (n.d.). An overview of Sulphur Dye [A to Z]. Blogspot.com. from https://textileapex.blogspot.com/2014/01/sulphur-dye.html
Sulphur dye definition. (n.d.). Law Insider. from https://www.lawinsider.com/dictionary/sulphur-dye
The Editors of Encyclopedia Britannica. (2011). sulfur dye. In Encyclopedia Britannica.
Continue reading,
Part 2 Sulphur dye - classification and stripping
Part 3 Application of Sulphur dyes to cotton
Part 4 Disadvantages of Sulphur dyes
