Application of Sulphur dyes to cotton
Soda ash and sodium sulphide are used to paste the dyestuff, which typically contains 5 to 25% of.
The amount of soda ash is the same as the amount of dye used, and the amount of sodium sulphide is between 50% and 200% of the weight of the dye.
The amount of sodium sulphide needed for several sulphur dyestuffs is shown in the table below.
Dye | Weight of sodium sulphide required |
(1) Sulphur blues | 1⁄2 to 3⁄4 the weight of the dye |
(2) Sulphur Yellows | 1 to 1⁄2 times the weight of the dye |
(3) Sulphur Browns | 1⁄2 the weight of the dye |
(4) Sulphur Red | 3⁄4 the weight of the dye |
Add a sufficient quantity of hot water to the paste and if necessary, boil it. then filter the dye solution to remove insoluble impurities.
Stages of applying sulphur dyes on Cotton materials
(B) Dissolution of dye
(C) Dyeing
(D) Oxidation
(E) Soaping
(F)After treatment -
(i) Metallic salts
(ii) Basic dyes
Explanations -
(A) Steps in dyeing:
Steps of dyeing cotton yarn in hank form with sulphur dyes are shown given below.
Dyeing Recipe :
Chemical | Quantity |
(1)Soda ash | 5 to 25 % |
(2)Dye | 5 to 25 % |
(3) Sodium chloride | 10 to 50 % |
(4) Sodium sulphide | 2.5 to 50 % |
(5) Temperature | 95 to 100°C |
(6)MLR(material to Liquor ratio) | 1:20 |
(7) Time | 1 hour |
After dyeing we have to do the oxidation of the sulphur dye to convert it into its original insoluble form so,
Oxidation Recipe:
Chemical | Quantity |
(1) Sodium perborate | 0.5 to 1 gpl |
(2) Temperature | 50°C |
(3) Time | 20 minutes |
(B) Dissolution of sulphur dyes
Soda ash and sodium sulfurate are accustomed to pasting the dyestuff. the quality dosage of washing soda is 2 g/l.
In most cases, twice the maximum amount of sodium sulphide is employed as colour.
The paste is next mixed with boiling water until the dye has been dissolved, and if necessary, the mixture is then dropped to a boil yet again.
Before adding the dissolved dye to the dye bath, strain it because sulphur colours are more likely than other dye classes to retain insoluble contaminants.
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| Sulphur dyed fabric |
(C) Dyeing
Maintain the bath's boiling temperature.
Place the items in the dye solution and then add common or Glauber's salt (10–50% of).
Depending on the shadow intensity, the amount will change. When adding the salt, do it gradually and keep the bath's temperature at boiling.
The actual amount varies counting on shade intensity.
The dye bath consists of dyestuff and 5 to 25% of the load of the products in common salt or 10 to 50% of crystalline Glauber's salts.
It's possible to feature the salt straight away, but if there's an opportunity for uneven dyeing, it's best to attend until the temperature reaches 100°C then add it in several sections.
It's advised to use a surface-active penetrating agent.
With the bulk of sulphur dyes, the liquid is heated to a boil before dying and is disbursed for a further half-hour in a very cooling liquor.
However, some sulphur dyes exhaust best between 70 and 75 degrees Celsius.
Particularly in dark colours, sulphur dyes don't provide superb exhaustion.
Therefore, a machine with an occasional liquor ratio is preferred. A standing bath is usually used because of the dark shade.
The things should be completely submerged during application because the reduced dye easily oxidises in the presence of air.
Immediately after dyeing, the excess liquor must be squeezed out and cleaned to avoid depositing the insoluble oxidation product on the fibres' surface.
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| Sulphur dyeing machine |
Questions -
- Explain the application of sulphur dyes for cotton materials.
- Which steps are involved in sulphur dyeing and give a recipe for that?
- What is the dissolution of sulphur dyes?
- What is the dyeing process for sulphur dyes?
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
