Dyeing laboratory: Lab is the most important section of the dyeing industry. The higher precision lab can aid easily to achieve the goal of the organization. Before bulk production, a sample for the approval from industry is sent to the buyer. As per the requirement of the buyer, the shade is prepared in a lab considering the economic aspects.

Lab Dip: Lab is the most important section of a dying industry. The higher precision lab can aid easily to achieve the goal of the organization. Before bulk production, a sample for the approval from industry is sent to the buyer. As per the requirement of the buyer, the shade is prepared in a lab considering the economic aspects.

The objective of Lab Dip:

The main objectives in lab dip are as follows:

• To calculate the recipe for sample dyeing.

• To compare dyed sample with swatch by light Box or Spectrophotometer.
• To calculate revise recipe for sample dyeing.
• Finally approved Lab Dip (Grade: A, B, C &D)

Color Measurement of Standard Sample: 

1. Manual Method 
2. Instrumental Method 

In the manual method, the std. sample color is measured by comparing it with previously produced samples of different trichromatic color combinations. The sample with which the color of the std. matched, that sample color recipe is being taken for shade matching. The instrumental method is more reliable if it is operated accurately to do the work of color measurement. A spectrophotometer interfaced with a PC is used for shade matching. In this way, color measurement of the standard sample is carried out for the purpose of shade matching.

Preparation and Storage of Stock Dyes and Chemicals: 

Preparation of Concentration of dye stock solution:

Normally 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 3% and 5% stock solution of dyes are    prepared in beakers for daily used. 

Preparation of Concentration of chemical stock solution: 

Similarly, 25% salt and 25% soda stock solutions are prepared in beakers for daily use. 

Dyes and Chemicals Measuring Formula for Laboratory: 

Total liquor = sample weight × Liquor Ratio (M: L)

 The amount of dye solution (ml) = 

 Amount of Chemical solution (ml) =  

  Additional Water = Total Liquor (ml) – Total Chemical Amount (ml)

Stock Solution Preparation:

Salt & Soda % according to Shade%

Example: Dyeing of 100% Cotton Fabric with Reactive Dye

Calculation:

Sample weight: 5 gm.

Total liquor:  5×8 = 40 ml

1. The amount of dye (Yellow 2GR) = (Fabric wt. × Shade %) ÷ Stock solution%

            = (5×1%) ÷ 1%

            = 5 ml

2. The amount of dye (Red 6BN)    = (Fabric wt. × Shade %) ÷ Stock solution%

                    = (5×0.53%) ÷ 0.5%

        = 5.3 ml

3. The amount of dye (Blue-LX   ) = (Fabric wt. × Shade %) ÷ Stock solution%

        = (5×0.142%) ÷ 0.5%

        = 1.42 ml

4. Amount of Salt Solution = (Total Liquor × Recipe amount (g/L) ÷ (1000× Stock %)

= (40 × 50)÷ (1000 × 25%)

= 8 ml

5. Amount of Soda Ash Solution = (Total Liquor × Recipe amount (g/L)÷ (1000× Stock %)

        = (40 × 14)÷ (1000 × 25%)

        = 2.24 ml

Total Chemical = (5 + 5.3 + 1.42 + 8 + 2.24) ml

      =21.96 ml

Additional Water Required = Total Liquor (ml) – Total Chemical Amount (ml)

  = (40 – 21.96) ml

  = 18.04 ml

Lab Dip Procedure: (100% Cotton)

Sample/ Swatch/ Panton no./ TCX no. / TPX no. from the buyer
↓

Recipe making→ from data color
↓
Recipe input in the automatic pipetting m/c
↓
Dyes & Chemical Stock Solution preparation →By Automatic pipetting m/c
↓

Required Solution input in the beaker → By Automatic pipetting m/c

↓
Fabric weighting & fabric input in the Beaker
↓
rising temperature at 60ºC (3ºC/min)
↓ 

Run time 60 Minute
↓
Decrease the temperature to 40ºC (3ºC/min)
↓ 

Beaker unload
↓
Normal Wash( Cold water) → Manually
↓
Wash at 90ºC hot water with Soaping/ Washing agent- 2g/l→ Washing m/c
↓

Run time 10 minute

↓
Decrease the temperature to  40ºC within 10 minute→ Washing m/c
↓
Fabric Unload
↓
Normal Wash(Cold water) → Manually
↓
Normal Hot wash 90ºC( Only water) → Manually
↓
Hydro/ Squeezing → Mini Hydro m/c
↓
Dry→ Drying m/c
↓
Ironing
↓
Shade Check → Light Box

↓
Shade Ok

↓
Send to Buyer Approval

Example: Dyeing of 100% Polyester Fabric with Disperse Dye.

Stock Solution Preparation:

Calculation:

Sample weight: 5 gm.

Total liquor:  5×8 = 40 ml

1.The amount of dye  (Yellow SFW ) = (Fabric  wt. × Shade%) ÷ Stock solution%

= (5×0.005%) ÷ 0.01%

= 2.5 ml

2. The amount of dye (Blue SFW) = (5×0.80%) ÷ 1%

      = 4 ml

3. The amount of dye (Blue-TFW) = (5×0.66%) ÷ 1%

        = 3.3 ml

4. Amount of Buffer Solution = required amount of solution to maintain pH 3.5- 4.5
5. Amount of Leveling Solution =   (5×0.5%) ÷ 1%

      = 2.5 ml

6. Total Chemical = (2.5 + 4 + 3.3 + 2.5) ml

      =12.3 ml

7. Additional Water Required = Total Liquor (ml) – Total Chemical Amount( ml)

        = (40 –12.3) ml

        = 27.7 ml

Lab Dip Procedure: (100%Polyester)

Sample/ Swatch/ Panton no./ TCX no. / TPX no. from the buyer
↓

Recipe making→ from data color
↓
Dyes & Chemical Stock Solution preparation →By manually

↓

Required Solution input in the beaker → By Manually

↓ 

Adding Buffer solution until to maintain the pH 3.5 – 4.0→ By Manually

↓
Fabric weighting & fabric input in the Beaker
↓ 

Beaker Set in the m/c
↓
Rising Temperature at 135ºC (3ºC/min) 

↓

Run time 40 minute
↓
Decrease the temperature to 40ºC (3ºC/min)
↓ 

Beaker unload
↓
Normal Wash→ Manually
↓

Reduction (In case of CVC/ PC; Carbonizing is done)
↓
Normal Wash

↓

Hydro/ Squeezing → Mini Hydro m/c
↓
Dry→ Drying m/c

↓
Ironing

↓
Shade Check → Light Box

↓
Shade Ok

↓
Send to Buyer Approval

Reduction Process (100% Polyester):

Reduction Recipe:

Hydrose    –         2g/l

Caustic Soda –    2 g/l

Washing agent – 2g/l

Temperature –     90ºC

Time       –           20 Minute

The reduction process is done in Gyro washing m/c which contains a cylinder.

Carbonizing Process (CVC/ PC):

Sulfuric Acid 60% + Water 40% solution

↓ 

Time 3-4 Minute → manually
↓
Soda Ash- 0.5g/l →For acid neutral
↓
Acetic Acid – 0.5 g/l→ for soda neutral

In the case of CVC/PC Fabric, At First, the polyester part is dyed, and then Carbonizing is done. After Carbonizing, the Cotton part recipe is made from a Spectrophotometer and then the Cotton part is dyed in the previous method.

About the Author

Md Saiful Islam

Join Our Fb Group