Introduction
The principal reasons for coloring textiles are for aesthetic appearance and decoration or for utilitarian purposes, and unless there is an unpredicted change in human behavior the majority of textiles will continue to be dyed to produce colored apparel, home furnishings, carpets, etc. Among the aesthetic uses are fashion garments and household articles such as drapes, towels, and carpets. In the utilitarian group are uniforms (military and civil), and work wear. In order for a colored substance to be regarded as a dyestuff, a number of requirements must be satisfied. A dyestuff must be substantive for a textile and exhaust from an aqueous solution into the fiber; have a high exhaustion; exhaust at a rate allowing economic processing; give a uniform level dyeing; and have satisfactory fastness for the particular end use the textile is intended for. The process of dyeing is therefore a combination of chemistry, application technology, economics, and customer needs.
Also, reactive dyes are a class of highly coloured organic substances, primarily used for tinting textiles, that attach themselves to their substrates by a chemical reaction that forms a covalent bond between the molecule of dye and that of the fibre.
Objective
Reactive dyes is used to identify the class of colorant on cellulosic fibre by the chemical reactions.
Apparatus
- Dyed fabric
- 0.1% non-ionic detergent
- Mixture of glacial acetic acid and ethanol (1:1 vol./ vol.)
- 1% ammonia solution
- Dimethylformamide
- Test tube
- Flat iron
- Mixture of dimethylformamide and water (1:1 vol./ vol.)
- Boiled water container
- Distilled water

Specimen Preparation
The dyed fabrics which will be tested should cut small pieces for the specific determination and those fabrics are dyed in blue.
Testing Procedure
For testing reactive dyes: 1. Boil for 15 min. (or until no further color bleeds out) in 0.1% non- ionic detergent to remove loose dye, rinse well and dry. 2. Then treat the sample for 4 min. at the boll in (a) - (d), in succession, rinsing the sample in distilled water after each treatment. a) Mixture of glacial acetic acid and ethanol (1:1 vol./ vol.) b) 1% ammonia solution c) Mixture of dimethylformamide and water (1:1 vol./ vol.) d) - dimethylformamide
Results and Assessment

Blue Reactive dyes

Discussion
In the test of reactive dyes, it observed that only blue specimen can withstand the treatment which conducted in the test. There is no color bleeding out in the above in five treatments.
Conclusion
Before the identification of colorants, fibre identification by burning test facilitates the colorant identification. Suitable treatments were used to identify colorants applied qualitatively. Reactive dyes was found to have the best fastness to all solvents among azoic, direct and vat dyes due to the strong covalent bond formed between dyes and cotton fibres.