1. ANALOG AND DIGITAL PRINITING COMPARISON R.B.CHAVAN DEPT. OF OF TEXTILE TECHNOLOGY INDIAN INSTITUTE OF TECHNOLOGY HAUZ-KHAS, NEW DELHI 110016

4. COLOUR SEPARATION Manual, Through computer with the help of suitable software

6. Screen coating with photo emulsion

7. Photo emulsion coated screen

8. Exposure to light Washing

9. Master image on screen

10. Printing operations Screen washing

11. MASTER IMAGE ON BLOCK

25. COMPARISON OF ANALOG AND DIGITAL PRINTING Special inks in small containers (usually 1 litre capacity) provided by machine suppliers Aqueous pastes are mixed up on site in large batches (Spot colours) 1-5 m/min. Speed 30-80 m/min DIGITAL PRINTING Digital printing bypasses the use of screens. Elimination of screens provides advantage in sampling and small runs at economical cost. The master design in the form of photograph or any design can be scanned and printed onto textiles. ANALOG PRINITNG Analog print uses master image in the form of screens, blocks, design rollers etc.

26. COMPARISON OF ANALOG AND DIGITAL PRINTING No difference between sample and bulk. Sample may be different than bulk Instant design registration Need time and skill for design registration Half-tones no problem Half tones not easy Non contact printing Contact printing No screens, No colour kitchen Screen costs, engraving, washing, storage Fully integrated with CAD Analog design information DPI 200 upto 1440 DPI 125, 225 max. Pre and post treatment necessary post treatment necessary

27. COMPARISON OF ANALOG AND DIGITAL PRINTING Process colours. Some limitations in colour gamut particularly CMYK four colour. Difficulty to produce bright reds, greens nd blues and many other colours desired by textile industry. Improvement in colour gamut by Hexachrome system: 6 colours includes orange and green in addition to CMYK, outside: Hexachrome Inside: CMYK Spot colours. Unlimited colour gamut

28. Paper printing VS fabric printing Require extended process colours CMYK process colours adequate Require more ink. Require less ink to produce particular depth of shade More absorbent. Textured surface. This difference has implications in speed, drop size, drop frequency, nozzle life. Less absorbent, plain, smooth surface Fabric Paper

29. Paper printing VS fabric printing Different inks for different fibres Limited ink types Stringent fastness property requirements Low fastness property requirements High DPI Low DPI for design resolution Fabric Paper