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Home > Important Published Papers > PRINTING OF DESIGNS ON COIR MATERIALS
PRINTING OF DESIGNS ON COIR MATERIALS
by A.Radhakrishnan, V.R.George Roy & U.S.Sarma, Proceedings of the International Workshop on Wet Processing of Coir 8-9 December 1997
ABSTRACT
The output on Printing on Coir Materials was commenced only after one year of the commencement of the activities in other outputs of the FAO Project on Softening, Bleaching, Dyeing and Printing on coir. The Literature and Industrial Surveys revealed a number of printing techniques in textiles, but incorporation of designs on coir mats/mattings, rugs could be effectively made at a low cost only with the stencil. Printing by all the other printing techniques could not be applied due to the uneven surface of the coir products

Attempts have been made to evolve and print designs on coir mats/mattings by stenciling based on synthetic enamel paints and dyestuffs . However, not much progress could be achieved due to the lack of essential facilities like computer Aided Design (Cad) system.
INTRODUCTION
The process of printing is used to achieve ornamentation and improve the aesthetic sense of the final product. The coir industry is an export oriented industry, exporting coir door mats, mattings, rugs, carpets etc, as decorative floor covering materials. The designs and patterns with attractive shade connotations are being applied to these products by printing for achieving more market value and popularity. The printing method most commonly adopted in the coir industry is Stenciling. The other printing techniques such as Roller Printing, Rotating Screen Printing, Hand Screen Printing, Wood Block Printing are not applied in coir industry due to the uneven surface of the coir products.

Coir mattings, either in rolls, or in pieces cut to specific lengths, as also the different types of coir mats are printed by brushing/spraying of colour pastes or dye solutions through stencils cut out from galvanized iron sheets. The dyes used are mainly basic, though selected acid and direct dyes are also used less often. The printed materials are only dried in air. The usual after-treatments like steaming etc. which from essential part of processing printed appeal textiles is found impractical due to the very nature of the material that is being processed. As such, the printing possess practically no fastness of water or rubbing. For improving the fastness characteristics of the prints with the conventional textile dyes, it is essential to steam the printed materials for varying periods depending upon the nature of the dyestuff and since this process has to be eliminated due to practical difficulties in processing the bulky materials and also because the appearance of the prints with" dyes" would be to a great extent marked by the colour of the substrate, there is only limited scope for investigations in regard to the printing of coir with the "faster dyes".

The organic or inorganic pigments in suitable formulation may be used in the printing of coir as they are opaque and do not have the shortcoming of being masked by the colour of the surface on which they are deposited. These of ready mixed paints diluted to the required consistency with suitable thinners or the application of pigments suitably dispersed in film forming components based on aqueous emulsion was therefore considered to offer the possibility of being an alternative to the application of dye solutions of colour pastes, for obtaining prints of improved fastness characteristics.
INDUSTRIAL SURVEY
Design development is on of the major needs for the creation of new markets as well as for upholding the existing markets for coir products. Designs suitable for the various seasons, suiting the trends and taste of consumers of different countries has got a great value in the export sector of coir. The designs evolved by traditional methods of manual drawing and colouring consumes a lot of time and energy especially in matching shades and colour mixing of the designs. These designs are made available to the product sector as design cards for incorporating them to their products.

The industrial survey revealed that newly developed designs evolved for coir products like mats, mattings, and rugs are transferred to them by two method viz. weaving and printing.
Weaving
It is a process of entanglement of warp and weft yarns to form products like mats, mattings and rugs. Using suitable dyestuffs, the good quality coir fibre/yarn is dyed in conventional/mechanised dye vats and processed in traditional wooden looms which require skilled labour. Weaving require more materials and man power than printing and wastage of dyestuffs is more than weaving. It is also not possible to make curved lines of designs on weaving which means that the possibility of making designs by weaving is limited to polygonal patterns.
Printing
The process of printing on coir is mainly based on the use of stencils. For the preparation of stenciled designs, the sketch of desired design is first prepared in the required size on paper. It is then transferred to thin sheet and then cut by hand. It is a stencil plate. Number of stencil plates depend upon the number of colours used in the design. One plate each for one colour and placed over the mats/mattings and the dyestuff is applied by spraying or brushing for mats and mattings respectively. The edges of the stencil plates were guarded with narrow strips of metal to avoid spreading of dyes while spraying on the coir products. Care should be taken to avoid over lapping of two colour of the same design during stenciling. Usually a stenciled design consists of 4-6 colours.

The printing require limited quantity of dyestuffs as it is impressed on the top surface only. The time consumption and man power is also less and hence cost of production is low compared to weaving.

The Industrial survey also revealed that creel mats, carnatic mats and fibre mats are the most common varieties of door coir mats used for printing designs. Designs can also be applied on these mats using the weaving methods as detailed below.
Fibre Mats: by lifting coloured fibre according to the design prepared on a graph while weaving.
Cree/Carnatic Mats: By arranging dyed yarn in the required colour combination of the loom
It is seen that the fibre mat is the most popular coir product. The survey confirmed that 20% of the total production of fibre mat are marketed as plain mats whereas 80% as woven or printed design mats in the ratio 40:60

About half (50%) of the total production of Carnatic/Creel mats are marketed in woven or printed designs and the rest is in plain form. Almost all the designs in the above mats are stenciled one due to the practical difficulties involved in the arrangement of dyed yarns during the weaving process.

The survey also brought that the consumers are very conscious on printed design on coir which should be fast to light, washing and rubbing.

The current need of coir industry is to adopt new product designs which can be effectively and meticulously developed by computer Aided Design (CAD) system. Before the application of a design on coir, the layout of the design has to undergo several trials in colour combinations. The design of an export quality coir mats/mattings normally consists of 5-9 colours. These colours are selected and matched after a number of trials. These trials can be done manually by printing each combinations using different colours. The whole process may take days to finalise a suitable combination for a design. With the assistance of a CAD, the maximum speed, accuracy and efficiency can be achieved in evolving designs and drawing and preparing additional copies of the designs.

The taste of consumer is also aimed at in buying coir products containing eco-friendly dyes/pigments which would not release the toxic amines.
EXPERIMENTAL
Materials
A list of the dyestuffs, plastic emulsion paint and synthetic enamel paint used for evolving floral designs and depicting nature's beauty by stenciling on creel/fibre coir mats are furnished in Annexure I

Based on the industrial survey of traditional designs used in coir floor furnishing materials, it is felt that a major modification is essential in terms of pattern layout and colour. An album was made by incorporating the designs evolved for coir products.
In the experimental stage, two types of paints were applied on coir mattings

a) Plastic emulsion paint in which the vehicle is water and

b) Synthetic enamel paint which is based on a volatile organic solvent.
The ready mixed emulsion/paint, suitably diluted was sprayed on the mattings and the coated materials allowed to dry in air. Sample cuttings of the shades were exposed on the Xenotest for the determination of the light fastness. It was observed that after a slight initial dulling after six to eight hours of exposure there was no further change in the tone.

Suitable length of the mattings sprayed with the paints were also fixed on to the staircase and elsewhere to examine the behavior of the coatings under service conditions. The synthetic enamel paints are observed to abrade or wear off slowly from the surface resulting in the loss of the gloss or lustre of the film. With the plastic emulsion paint, the colour is rather subdued, but comparatively this offers greater resistance to abrasion or wear. Both the types of paints sprayed and dried on the mattings show excellent fastness to water.

It is of interest to note that due to the opaque nature of the film one could overprint a light colour design on a dark coloured background or vice versa using plastic emulsion paints for the purpose. The application of the paints would be particularly worth while for producing coir mattings in pastel shades, which are reportedly in good demand in overseas markets.

The specimen of door mats were stenciled with synthetic enamel paints and coir dyestuffs so as to achieve different shades to evolve floral designs and nature's beauty. These printed designs were exhibited in trade fairs for assessing the receptivity of consumers. Photographs of the printed designs were made into an album for reference of the exporters.
In another experiment an apple design was printed with the following receipe based on reactive dyestuff on fibre mat.
  Receipe:
Procion Brilliant Red M8B      10g/l
Urea    10g/l
Sodium bicarbonate                 10g/l
The reactive dye stuff solution was sprayed on the mat and subsequently dried in room temperature. It was observed that the penetration was deeper coupled with brilliant hue. The light fastness was also measured by subjecting the mat in direct sun light for 15 days. It was observed that the fading occurred to the extent of only 10% which is better when compared to the traditional printing with basic dyestuff.

The cost aspect of the printing was calculated at Rs.1.05 to cover 75% of the total area of the mat. The cost details are furnished in Annexure-II
RESULTS AND DISCUSSION
Stencil Printing is the most widely adopted technique for incorporating designs on coir mats/mattings. Synthetic enamel paints and reactive dye stuff can be used for achieving prints of better light fastness and deep penetration. It is desirable to adopt computer Aided Design (CAD) system in coir industry also for effecting maximum efficiency, speed and accuracy involving designs suited to the taste and trend of people of different countries by blending of colour combinations and make copies of designs.

It is advantageous to use eco-friendly dyes so as to avoid the release of toxic and banned amines. The use of dye derived from natural resources such as plants, insects, and minerals on coir are to be encouraged.

The designs already evolved should be transferred to coir materials for assessing the marketability and receptivity among consumers.
ACKNOWLEDGEMENT
The authors are indebted to the FAO for extending the assistance in conducting the project and grateful to the Coir Board in permitting to publish this paper.

Reference

1.Terence Conran: Printed Textile Design, Industrial Printing methods P 13,14
2.Standard methods for the determination of the colour fastness of Textiles,Colour fastness to day light P.46-50
3.Dr.Lous Diserens : The chemical Technology of Dyeing and Printing Basic Dyestuffs. P.84,Acid Dyes,P.311-315, Pigments, P.370-410
4.ICI-Procion Dyestuffs in Textile Printing, Printing of Cellulosic fibres P.1-10
ANNEXURE-1
DETAILS OF MATERIALS USED FOR PRINTING DESIGNS ON COIR PRODUCTS
1. Synthetic enamel paints
2. Compressor/spray Gun
3. Dye stuffs
4. Urea *+
5. Sodium bicarbonate
ANNEXURE-II
COST PARAMETERS OF PRINTING WITH REACTIVE DYESTUFF
Basis: 4 mats (each of area o.34m2 )
Receipe Qty used g/l Cost Rs.
Procion Brilliant Red M 8 B 10.00 4.00
Urea 10.00 0.05
Sodium bicarbonate 10.00 0.15
Total cost for printing of 4 mats      : Rs.4.20
Cost for printing one mat                  : Rs.1.05