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Acid dyes are sodium salts of sulphonic acid but there are a few containing Carboxyl groups. The acid dyes have a direct affinity towards protein fibers and polyamide fibers. Applicable for wool , silk, nylon. Applied from an acidic dye bath. The fastness properties of this dye-stuff depends on the fiber type.

Recipe:

Acid dye — 2%
Acetic acid – 1 gm/L
Leveling agent — 1 gm/L
pH = 4.5-5.5
Temp × Time = 90ºc × 30 min
M:L = 1:20.

Calculation:

Sample weight = 5 gm
Total liquor = 5×20= 100cc
Dyestuff require =( Sample wt x % of the dye ) / % of the stock solution = (2%× 5)/1% = 10cc
Required Acetic acid = (1 × 100)/(1000×1%) = 10cc
Required leveling agent = (1 × 100)/(1000×1%) = 10cc
Additional water require = 100- (10+10+10) = 70 cc

Fig: – Dyeing curve on Nylon fabric.

Procedure:

First required amount of water and leveling agent is mixed in a closed vessel.
Then added dye to this mixture.
Then added Acetic acid.
Finally sample is taken in this solⁿand closed the open end of the vessel.
Then vessel is kept on the rotadryer m/c and heated 90° c for 30min.
Then the vessel is open and the sample is drawn out.
Then the sample is drawn out and washed with water.

Precaution:

The sample should be kept uniformly in the mixture. Otherwise non-uniform dyeing will do.
Amount of chemical and water must be accurate.
Chemical must mix with water very well.

Conclusion:

Dyeing is an important experiment in textile technology. Nylon is the mostly used fibre from old ages to now. So, this experiment will do a great favor to us in future days.

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