The importance of the contribution of value-added products in boosting textile exports was forcefully demonstrated in 2002-03. The textile exports crossed the 5.5 billion US$ mark for the first time in the history of Pakistan reaching US$ 7.169 billion. This outstanding export performance was achieved mainly due to increase in the export of value-added product categories such as knitwear, bedwear, ready-made garments, each of which crossed the US$ 1.00 billion mark for the first time.

onsequently, total exports from Pakistan increased to US$ 11.03 billion [1].

During the manufacture of finished fabrics from textile fibres, value is added at all process stages involved in spinning of yarns, knitting or weaving of fabrics. However, the scope of value-addition in the processes subsequent to fabric formation is comparatively much higher. By the application of appropriate colouration and finishing technology beautiful value-added fabrics with soft handle, drape, dimensional stability, durability and attractive visual appeal can be created and exported. By concentrating on the manufacture of such value-added products the textile industry can not only maintain but also improve upon its export performance recorded in 2002-2003.

However, for achieving this objective the textile industry must be fully up-to-date with the latest developments in the field of colouration of textiles.

The Textile Institute of Pakistan has always been in the forefront in keeping the textile industry fully abreast with the modern developments in textile technology in general, colouration and finishing of textiles in particular. Since the advancement and dissemination of knowledge is a mission of the Textile Institute of Pakistan (TIP), it is always on the lookout for on opportunity to perform this noble task for the textile industry of Pakistan.

Such an opportunity was recently provided by Dr. Chris Hawkyard, the well-known authority on colour science, who visited Pakistan for a short period. Mr. Shakeel Ahmed, the President of TIP, lost no time in arranging a Seminar in collaboration with APTPMA and S.I.T.E. on 5th of January, 2004 and invited Dr. Chris Hawkyard to deliver a lecture on colour communication. The Seminar was attended by a large number of technical personnel working in the wet processing and finishing sectors of the textile industry, students of textile institutes, TIP and V.I.P's of the industry.

Mr. Nisar Sheikhani, Chairman S.I.T.E. was Chief Guest of the Seminar. Dr. Arshad A Vohra, Technical Director, Moonlight Industries, represented the All Pakistan Textile Processing Mills Association (APTPMA).

Inaugurating the Seminar Dr. Arshad A. Vohra welcomed Dr. Chris Hawkyard , Mr. Nisar Sheikhani, Mr. Shakeel Ahmed and participants. He recalled that during 1982-86 he met Dr. Hawkyard in U.K. when he was studying for Ph.D. At that time Dr. Hawkyard was doing his Ph.D and also working as a lecturer. It was a pleasure to meet Dr. C. Hawkyard again.

Addressing the participants Mr. Shakeel observed that it was important to give some information about the back ground and history of the TIP. Ten years ago gap between the annual requirements of qualified and trained man-power of the textile industry and the number of textile graduates being produced by the textile institutes was very wide. APTMA realised the urgent necessity of setting up another textile institute to bridge this gap to the extent possible. APTMA set up the Textile Institute of Pakistan. TIP has now an independent charter and a degree awarding status! It is producing textile graduates conforming to standards required by the textile industry.

TIP has so far produced about 200 graduates and all of them have been absorbed in various sectors of the textile industry at good starting salaries.

However, it must be pointed out that shortage of textile graduates still persists! As per statistics given by Dr. Arshad A. Vohra [2] the total requirement of educated technical man-power is 12750 per annum against which the availability is only about 7950. The current shortage therefore works out at about 4800.

In addition to offering courses leading to BSc (Hons) degree in textile science, textile design, textile management, apparel manufacture and merchandising, TIP started MSc. Textile chemistry programme last year in order to provide research impetus to industrial growth. TIP is also contemplating to introduce some more graduate and post graduate courses.

TIP has also started conducting quality audit of textile mills free of charge. This work is done by the final year students of TIP. One such exercise was conducted recently in two textile mills situated in the industrial area near Lahore. It was highly successful. The concerned managements were so much impressed that they offered jobs to both batches of the students!. We have made standing arrangements for independent evaluation of the course contents, teaching methodology, examination technique of our educational programme by well known professional scholars.

· Dr. Sanaul Mullick, Principal Lecturer at London college of Fashion, evaluates our under inaduate courses.

· Dr. Chris Hawkyard (formerly lecturer in colour science and printing at UMIST) evaluates our MSc. (Textile Chemistry) course.

· Teams of experts are being arranged for evaluation of our Textile Design courses.
Our aim is to get recognition for TIP as a centre of excellence and facilitate employment of our graduates by the textile industry. This partnership between TIP and the textile industry is proving beneficial to all concerned.

Finally Mr. Shakeel Ahmed thanked Dr. Arshad A. Vohra for cooperation in arranging the seminar.
Dr. Zubair Bandukda, dean of TIP came to the stage and introduced Dr. Chris Hawkyard, who worked in the industry for 11 years before joining UMIST as a lecturer in colour science and printing. He is a member of the Society of Dyers and Colourists (SDC). He also visits UMIST as an honorary lecturer on part time basis.

Dr. Chris Hawkyard also visited Pakistan three years ago and gave a lecture at the British Council [3]. It is a matter of great pleasure to invite him to deliver his lecture at this seminar.

Dr. Chris Hawkyard thanked TIP for arranging the Seminar and his lecture. He informed that last time he talked about Digital printing. He observed that Ink Jet Printing is not being used as a production method in Pakistan. However, he was happy to note that colour measurement was being practiced in the textile industry of Pakistan and cited the example of M/s. J & P Coats, who were well equipped in this field.

He also informed that colour measurement was a hot topic with SDC and that a branch of SDC would be formed in Karachi. After these preliminary remarks Dr. Chris Hawkyard started his solo lecture, salient features of which are reported as under:

1. Colour Communication
Colour can be divided into following groups:

· Achromatic (black, white and greys)

· Chromatic ( red, yellow, green, etc.)

Colour is generally accepted as being three dimensional, the dimensions being HUE, LIGHTNESS and SATURATION (Purity, vividness).

Hue is the name given to a particular visual sensation. Lightness can be defined as the closeness of approach to white; Likewise darkness is the closeness of approach to black. A measure of saturation of a colour is the difference between it and a grey of same lightness. Colour can be communicated by the following seven ways:

· Verbal description
· Physical samples
· Reference in a colour atlas
· CIE XYZ or LAB
· Reflectance Data
· On-screen display
· Graphic/digital data

The colours in the visible spectrum perceived by the eye optic nerve, brain system are in the wavelength range of 400 nm to 700 nm. i.e. violet, indigo, blue, green, yellow, orange and red.

2. Colour Systems

The Munsell Colour System was launched in 1905 when Professor A. H. Munsell published his book entitled, " A colour notation". Ten years later he published the Munsell Atlas of colour. The three variables in the Munsell Colour System are HUE, Value (Lightness) and Chroma (Saturation). The Natural Colour System (NCS) is another vivid colour system. It is based on 6 elementary colours ie white, Sian, yellow, red, blue, and green. NCS is used by I.C.I and other organizations.

3. Colour Atlases

Atlases rely on observer having good colour vision. Humans can distinguish upto a million colours. Following Atlases are being used now-a-days:

· PANTONE System based on colour, magenta, yellow, black or spot colours. This system is very popular in the Italian Textile Industry.· RAL ATLAS (based on Lab space) German.
· Colour Curve (USA).
· OAS System (USA)

3.1 Problems with Atlases
· The same background must be used, ideally mid grey.
· The lighting conditions must be specified, e.g. day light, D 65.
· Only a small selection from the total number of colours distinguishable by human observers can be represented in a printed Atlas, typically about 1600.
· They are subject to determination due to handling and exposure to light.
· The colour gamut is restricted due to the inks/pigments availability.

4. Tristimulus Values
In 1931 an International Commission on illumination (CIE) established three variables labeled x,y,z, which defined colour both for lights and surfaces. The CIE system takes into account the illuminant or light source, the colour vision of the standard human observer and in the case of a surface, its reflectance properties.

X.Y.Z are considered as supersaturated red-green and blue lights respectively. The amount of these stimuli which when they are mixed, (additive mixing - not substractive as with dyes and pigments) match the colour are the tristimulus values of colour. The illuminant which has equal power at all visible wave-lengths (E) has X=Y=Z = 100. Since the perfect white surface reflects 100% of the incident light it will also have X=Y=Z=100. All other surface colours will have lower tristimulus values.

5. Colour Mixing / Additive Mixing

Most shades can be matched with 3 primary colours, red, green, and blue which are considered as Ideal set of primaries. Human eye has three different type of perceptors. Red, green and blue on mixing are perceived as best gamut. Black (Schwarz) is the 4th primary represented by the letter K.

· Overlapping red + green gives yellow.
· However, mixing of red (pigment) and green (Pigment) will not give yellow.
· Blue paint and yellow paint on mixing will give green colour but blue light and yellow light when mixed will give white.

The factors important in colour matching are power distribution of the light source, colour matching characteristics of the standard observer and the reflectance of the surface at each wave length. The perfect black has 0% reflectance at every wave length, so far all illuminants X=Y=Z=O for perfect black surface.

6. Colour difference formulae

The Munsell Grey Scale is non-linear. The lab colour space is based on the measurement of Grey scale. Perception of grey scale is non-linear. In colour difference measurement the dimension in the formulae published in 1976 are L*, 2* (ref/green) and b* (yellow/blue). So the three dimensions of difference are:

· DL = L sample - L standard
· Da = a of sample - a of standard
· Db = b of sample - b of standard

The D E the colour difference = (DL2 + Da2 + Db2) ½ in CIE L*, A*, b* difference units, DE is the colour difference in colour space between the sample and the standard.

If DE is above 1 , - `fail'
If DE is less than 1, `pass'

Another formulae for measuring colour difference is the Tolerance Ellipse based formulae which has more advanced tolerance definitions:

CMC (l:c) DE = (EQUATION.
Sl, Sc and SH are defined by a set of complex equations, which map the visual acceptability of tolerances in each dimension.

7. Measurement of X, Y and Z

X,Y,Z stimuli are measured by an instrument called a Colorimeter. Colorimater has a light source and 3 or 4 fillers with transmission curves similar in shape to the colour matching functions of the standard observer.

7.1 Limitations of Colorimeters
The main limitation of colorimeters is that x,y, and z stimuli are measured for one illuminant only and they do not measure reflectance data. Thus, it is not possible to measure and assess colour constancy and metamerism. However, colorimeters are cheaper than spectors and good for process control.

8. Spectrophotometers

Spectrometers incorporate, one arc or two monochrometers, which split up the light into its constituent wave lengths. They measure reflectance (% of incident light reflected). Modern dual monochromater type instruments are accurate upto 3 decimal places. The associated software can calculate X, Y, Z, L, a, b etc. for any illuminant or source for which power distribution data is available. Spectrophotometers can, therefore, indicate matamerism and colour constancy.

9. Reflectance Data

The % reflectance of incident light is finger print and true representative of colour. The reflectance curve of a coloured surface is independent of the illuminant. Provided the measurement conditions are the same and the reflectance curve of the batch matches that of the standard, the pair will match under all lights. Now-a-days reflectance data is used to relay colour information around the world electronically (by e-mail or web). Marks and Spencer (M & S) use 16 point data (% R at 400, 420, 700 nm) whereas others use 31 or even 41 point data (every 10 nm). These numbers are matched to produce true representation of colour design required by the end-user.

10. On screen colour systems

· At present the main on-screen colour systems are:
· Shade master ( 1991) - UMIST
· Image Master ( 1995) - UMIST
· Colorite - Data Color
· True Colour Loughborough Derby
· Gretag - Macbeth
The requirements for these systems are:
· A high resolution colour monitor
· An instrument to calibrate the screen, a colorimeter (3 or 4 filters) or a telespectroradiometer ( many spectral points).
· Suitable software
· Optional output to a calibreted printer.
The above listed systems make colour matching and quality control simple and easy. Since true on-screen colour is delivered physical samples are replaced with digital samples reducing the cycle time for colour approval. Thus the end-user gets the assurance that any products received from their respective suppliers will arrive in the right colour and shade, the first time, every time.
Dr. Chris Hawkyard delivered his interesting lecture with full backing of multi-media display. At the end of his lecture, the participants asked questions and received satisfactory replies.
The seminar concluded after a presentation ceremony in which shields of the Textile Institute of Pakistan were presented to

i) Dr. Chris Hawkyard by Mr. Nisar Sheikhani
ii) Mr. Shakeel Ahmed by Dr. Arshad A. Vohra.
Dr. Arshad A. Vohra was prominent in conducting the seminar. Participants were entertained with refreshments.

Acknowledgement
Technical information received from M/s. Tariq Sohail, Faraz Mehmood, Adeel Minhaj and Mohammad Saeed (3rd year students) in preparation of this report is gratefully acknowledged.

References
1. Dawn Reporter, " Exports stand at US$ 11.03 billion in 02-03", Dawn dated 06/07/2003.
2. Dr. H. R. Sheikh, "Marketing opportunities in global textile and fashion apparel environments", Pakistan Textile Journal, may 2003.
3. Dr. Chris Hawkyard, " Colour Communication", Pakistan Textile Journal, March 2001.