Washing printing process

An especially important and critical aspect of the application of reactive dyes, whether by dyeing or printing, is the washing-off process necessary to remove unfixed or hydrolysed dyes,... 

Virtually all commercial textile dyeing and printing processes take place by the application of a solution or a dispersion of the dyes to the textile material followed by some type of fixation process. The dye solution or dispersion is almost always in an aqueous medium. A major objective of the fixation step is normally to ensure that the coloured textile exhibits satisfactory fastness to subsequent treatment in aqueous wash liquors. In view of the overriding importance of water as a transfer medium in dyeing and printing it seems reasonable to begin with a discussion of the properties of dyes in solution and in dispersion. 

The basic light-sensitive substance used in all of these papers is silver chloride with an excess of silver nitrate. Once the image has been printed and toned, it is fixed, washed, dried, and preserved in much the same way as a silver print. Because the silver particles of printed out images are a much finer size than those of developed out prints, they are often more susceptible to deterioration. But with proper processing, they will stand the test of time as well as any process. Indeed, collodio-chloride is actually the most stable silver printing process because the nitrocellulose binder hermetically seals the silver from the harmful atmosphere that fades all silver base photographic prints. 

Print adhesion on plastics (and foil) is normally checked using a self-adhesive tape peel test. A few inches of a suitable standard tape is firmly pressed onto the print area then pulled off, slowly at first, then more rapidly. An assessment of print adhesion can be made from the quantity (ideally none) removed. Adhesion can vary according to the type and colour of the ink, the degree of pretreatment, the surface involved and the printing process, etc. In order to test print under likely use conditions, product immersion tests may be necessary 60°C (140°F) is a frequently used condition, for 3 to 6 h. If product-pack may be used with soapy hands, a solution of soap can be employed. A print adhesion test, as above, can then be carried out, on the washed material, after it has been cooled to room temperature. 

Consideration of the impact of washing and water within the life cycle of inkjet printed textiles might be complemented by steps in the supply chain that are upstream or downstream from the inkjet print process. Downstream are the uses for the printed cloth, usually as raw material for another industry, such as fashion, before it reaches the final consumer. Upstream, the process of inkjet printing on textiles, can be considered to begin with the preparation of the fabric for ink jet or digital printing. 

This additional step in the printing process, with the introduction of an object, either stamp or stencil in whatever form, has the most far-reaching consequences for the use of water, because this additional item will need to be washed. Water under pressure is often used to remove excess stencil film or material residue during the... 

The screens are manufactured by stretching a mesh tightly over a printing frame to a prescribed tension. The stretched screen is then coated with a layer of photosensitive polymer and dried, before exposure to ultraviolet light. A photopositive which may have been produced at 2 1 original size is then used to protect required stencil areas from exposure and subsequent polymerization, these areas remaining soluble in warm water in the final wash-out process. 

Fill up all necessary liquids, including dH O, printing buffer, and wash buffer. Start the printing process (see Note 6). 

Uses Antifoam for washing, dyeing and printing processes... 

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