Computer Colour Matching System (CCMS):
Computer Colour Matching (CCM) is the instrumental colour formulation based on recipe calculation using the spectrophotometric properties of dyestuff and fibers. Generally garment buyer gives a fabric sample swatch or Pantone number of a specific shade to the garment manufacturer. Then the manufacturer gives the fabric sample to lab dip development department to match the shade of the fabric. After getting the sample they analyze the colour of the sample manually. It is a laborious, time-consuming and critical task and needs skills and expertise of the personnel developing the lab dip. On the other hand, to save time and money, they can use computer colour matching system (CCMS).
Computerised colour matching system performs two functions. The first one is selection. It means determinations of one or more practical combinations of compatible dyestuffs which are expected to match with the given shade satisfactorily at reasonable cost. The second thing is that the colour formulations are determined as to how much amount of each colourant should be used to produce a satisfactory match. It means that there are usually more than the combination of dyes which will match the required shade. The computer tries to match the standard with the all possible combinations of dyes and lists the resulting formulas in best match and cost consideration. The colourist can then choose a matching formula from the list considering the closeness of the match, cost and other relevant factors. A computerised colour matching system is shown in the block diagram (Figure 2).
- Drive filters
- Display colour coordinates.
- Command recogniser.
- Data acquisition and storage.
- Computations display.
- Self diagnosis and calibration.
The basic three things are important in CCMS:
- Colour measurement Instrument (Spectrophotometers).
- Reflectance (R%) from a mixture of Dyes or Pigments applied in a specific way.
- Optical model of colour vision to closeness of the colour matching (CIE L*A*B).
Functions of Computer Colour Matching System:
The following works can be done by using CCMS –
- Colour match prediction.
- Colour difference calculation.
- Determine metamerism.
- Pass/Fail option.
- Colour fastness rating.
- Cost Comparison.
- Strength evaluation of dyes.
- Whiteness indices.
- Reflectance curve and K/S curve.
- Production of Shade library.
- Colour strength
Above functions of computer colour matching system are described below:
A. Colour Match Prediction:
The main function of CCMS is to predict the colour of a sample. In lab dip section it is necessary to match the shade of the sample. CCMS makes it easy to match the shade quickly. It also makes easy the work of a textile engineer who is responsible for it.
B. Colour Difference Calculation:
We know that; when a sample is put in sample holder of a spectophotometer it analyzes the colour of the sample. It also calculates the colour difference of the sample and dyed sample which is dyed according to the recipe of the CCMS.
C. Determine Metamerism:
CCMS also show the metamarism of the sample colour.
D. Pass / Fail Option:
The sample which is dyed according to the recipe of the CCMS is it matches with the buyers sample that could be calculate by this system. If the dyed sample fulfill the requirements then CCMS gives pass decision and if can’t then it gives fail decision. So, pass-fail can be decided by CCMS.
E. Colour Fastness Rating:
colour fastness can be calculates by CCMS. There is different colour fastness rating (1-5/1-8). CCMS analyze the colour fastness and gives result.
F. Cost Comparison:
Cost of the produced sample can be compare with others. It also helps to choose the right dyes for dyeing.
G. Strength Evaluation of Dyes:
It is important to evaluate the strength of the dyes which will be used for production. All of the dyes have not same strength. Dyes strength effects the concentration of dyes which will be used for dyeing.
H. Whiteness Indices:
Whiteness Indices also maintained in CCMS.
I. Reflectance Curve and K/S Curve:
Reflectance curve also formed for specific shade by which we can determine the reflection capability of that shade.
J. Production of Shade Library:
Computer colour matching system also store the recipe of the dyeing for specific shade. This shade library helps to find out the different documents against that shade. It is done both for the shade of sample and bulk dyed sample.
K. Colour Strength:
Computer colour matching system also determine the colour strength of the sample.
Implementation of Computerized Colour Matching System:
The implementation of computerized colour matching involves many steps to get started. The first and most important one is to make laboratory dyeing which represent multiple concentrations of the primary dyes characterising the affinity of each dye to the fibre. These dyeing are then read individually by spectrophotometer to obtain the percentage of reflectance curves which represent the resultant colour. This data can be directly keyed in to the computer through a direct computer spectrophotometer interface. Graphical plots of the data may be obtained from the system to verify the accuracy, identify errors, analyse the dyes, compare to other dyes and so on.
Working Procedure of Computer Colour Matching Systems (CCMS):
The working principle of computerised colour matching system is shown in the Figure 3.
It consists of an integrating sphere with non-polarising optical design to virtually eliminate orientation measurement errors of textured sample. The system uses a single beam technique. Five inch diameter sphere is used for diffuse illumination. The reflected light passes through a rotating filter disc and directed on to a solid state silicon photo detector. The analogue signal is converted in to digital form by DVM interface and the computer converts the data to different point wavelength information.
The microprocessor controls all the functions regarding the operation of the colourimeter. The rotating filter disk is controlled by stepper motor. A total of eight data points representing the visible spectrum from 400 nm to 700 nm are taken for the recommended single filter disc rotation.
The working procedure of CCMS which is used for dyeing lab to match the shade of the products. We already discussed that buyer gives a fabric sample swatch or Panton number of a specific shade to the producer. Producer gives the fabric sample to lab dip development department to match the shade of the fabric. After getting the sample they analyze the color of the sample manually. In the other hand they can take help from the computer colour matching system.
At first it needs to fit the sample to the spectrophotometer which analyzes the depth of the shade and it shows the results of the colour depth. At the same time it needs to determine the colour combination by which you want to dye the fabric. Then it will generate some dyeing recipe which is nearly same. Here it needs to determine the amount of chemicals which you want to use during dyeing.
After formation of dyeing recipe it needs to dye the sample with stock solution. I think you are also familiar with stock solution. Then sample should dye according to the dyeing procedure. After finishing the sample dyeing it needs to compare the dyed sample with the buyer sample. For this reason dyed sample are entered to the spectrophotometer to compare the sample with the buyer sample.
Then CCMS gives the pass fail results. If the dyed sample match with the buyer sample than CCMS gives pass results. After that, dyed samples send to the customer or buyer. After getting the approval from the buyer producer goes for the bulk production.
If the dyed sample does not match with the buyer sample than the CCMS analyses the colour difference and correct the recipe. Then another sample dyeing is carried out for matching the shade of the sample.
Advantages of Computer Colour Matching System (CCMS):
Computer Colour Matching System (CCMS) has lots of great advantages in Textile Industry. See some examples below –
- Customers get the exact shade wanted with his knowledge of degree of metamerism.
- Customers often have a choice of 10-20 formulation that will match colour. By taking costing, availability of dyes, and auxiliaries into account, one can choose a best swatch.
- 3 to 300 times faster than manual color matching.
- Limited range of stock colour needed.
- Control Systems in Textile Machines By G. Nagarajan and Dr. G. Ramakrishnan
- Principles of Colour Appearance and Measurement Volume 2: Visual Measurement of Colour, Colour Comparison and Management by Asim Kumar Roy Choudhury
- A Practical Guide to Textile Testing By K. Amutha
You might also like:
- Spectrophotometer in Textile: Components, Principle and Uses
- Basic Concepts of Colour Measurement
- Computer Color Matching (CCM) System
- Procedure of Lab Dip Development by the Different Dyestuff in the Laboratory
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. He is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.