Screen printing is ane of the pop printing techniques. It is an quondam historic period process. Different screen is needed for each color. In this printing method, meshing is used to transfer ink onto a substrate, except inward areas made impermeable to the ink past a blocking stencil. H5N1 blade or squeegee is moved across the concealment to fill up the open meshwork apertures alongside ink, in addition to a opposite stroke and so causes the cover to impact the substrate momentarily along a business of contact. During screen printing procedure or so common defects come about. Important covert printing defects, causes too remedies are explain below.
|Fig: Screen printing|
Screen printing defects:
ane. When uneven pressure level is exerted past the squeegee during the stroke, the resulting print becomes lighter on i selvedge together with becomes gradually deeper towards the other. Uneven steaming may as well atomic number 82 to this mistake.
two. The prints may come up out lighter inward the eye in addition to deeper towards the selvedges. This occurs when likewise much cloth is steamed inward 1 batch or when the cloth is very thick.
three. Very small-scale specks of color appear on the ground (unprinted portions) when the covert has tiny holes inwards the blocked areas. In this example, the cover should live inspected and lacquer applied at these places.
iv. When the printing has likewise much solids in it, specially inwards paint printing, the cover may got choked during working. This results inward light prints subsequently working for roughly time.
5. When the concealment is placed on a previously printed expanse amongst some other color, which is non dried, the back of the covert picks up more or less glue as well as transfers it to the adjacent area where it is placed, leading to smudging of the print.
half-dozen. Deeper prints are obtained irregularly throughout the cloth. This may due to uneven table surface in addition to thence the squeegee exerts different pressures at different places.
seven. Deeper prints seem throughout the material in the management of the weft (management of the squeegee stroke). Uneven border of the squeegee leads to this mistake. This may remedied by sharpening inwards the squeegee border.
viii. If the squeegee vibrates spell applying the pressure level deep stripes along the warp look.
ix. When a glue containing a big sum of foam is printed, lighter prints are obtained throughout the material.
10. Lighter prints occurring irregularly may live due to uneven application of eh mucilage patch fixing fabric on the tabular array.
eleven. If a soft tabular array is used on a hard tabular array surface deeper prints are produced. On the other hand, if a difficult squeegee is used on a soft tabular array surface, fine lines of the designs are not obtained.
You tin may similar: Difference between Rotary Screen Printing and Roller Printing
Roller printing is i of the almost economical too fasted style of printing. It is likewise called straight printing. Influenza A virus subtype H5N1 sort out dye paste for each colour is applied to the material from a metal roller that is intaglio engraved according to the pattern. Designs alongside upwards to sixteen colors introduce no job inward roller printing. Common causes and remedies of roller printing are given below:
Roller printing defects:
one. When grit particles in the printing paste cut the smooth surface of the unengraved roller, the scratches produced will besides transfer the paste to the cloth. By burnishing the roller besides every bit by straining the printing glue once again this mistake may live removed.
ii. Sometimes large double stripes of color called snappers look along the length of the material due to firm coming under the color physician edge. Washing, cleaning the doc blade, roller as well as filtering the paste are to forbid this defects.
three. Very minute snappers called litts are produced at regular intervals on the material because of particles of steel getting embeded inward the engraving of the roller. Cleaning the roller engraving can prevent this mistake.
4. Streaks look equally fine lines or serial of lines running along the piece as well as parallel to selvedge due to scratches on the engraved roller together with cutting in the color physician blade edge. Polishing the roller in addition to sharpening the MD blade border tin remedy this job.
5. Scumming is the fault arising out of insufficient scraping of the printing glue from the unengraved component part of the printing roller past the physician blade.
6. Uneven printing is some other error due to the faulty of the material, the roller, the printing paste too working of the motorcar.
7. The printed textile with deeper shades nearly one selvedge than most the other due to uneven pressure exerted past the engraved roller on the pressure bowl too faulty setting.
viii. If the plumbing equipment of the engraved roller on the mandrel is not perfect, it slips spell rotating, this defect known every bit lobbing of the engraved roller.
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