Flat-screen and rotary-screen printing are both characterized by the fact that the printing paste is transferred to the fabric through openings
in specially designed screens. The openings on each screen correspond
to a pattern and when the printing paste is forced through by means of a
squeegee, the desired pattern is reproduced onthe fabric. A separate
screen is made for each color in the pattern.
Flat-screen printing machines can be manual, semi-automatic or completely automatic. One type of machine, which is still commonly found in printing houses, can be described as follows.The fabric is first glued to a moving endless belt. A stationary screen at the front of the machine, is lowered onto the area that has to be printed and the printing paste is wiped with a squeegee. Afterwards the belt, withthe fabric glued on it, is advanced to the pattern-repeat point and the screen is lowered again. The printed fabric moves forward step by step and passes through a dryer. The machine prints only one color at a time. When the first color is printed on the whole length ofthe fabric, the dried fabric is ready for the second cycle and so on until the pattern is completed.
In other fully mechanized machines all the colors are printed at the same time. A number of stationary screens (from 8 to 12, but some machines are equipped with up to 24 different screens) are placed along the printing machine. The screens are simultaneously lifted, while the textile, which is glued to a moving endless rubber belt, is advanced to the pattern-repeat point. Then the screens are lowered again and the paste is squeezed through the screens ontothe fabric. The printed material moves forward one frame at each application and as it leaves the last frame it is finally dried and it is ready for fixation.
In both machines the continuous rubber belt, after pulling away the fabric, is moved downward in continuous mode over a guide roller and washed with water and rotating brushes to remove the printing paste residues and the glue, if necessary. After this, the belt is sent back to the gluing device. In some cases the glue is applied in liquid form by a squeegee, while in other machines the belts are pre-coated with thermoplastic glues. In this case thetextile is heated and then it is squeezed by a roller or simply pressed against the rubber-coated belt, causing the glue to soften and instantly adhere.
After printing, the screens and the application system are washed out. It is common practice to squeeze the color from the screens back into the printing paste mixing containers before washing them
Flat-screen printing machines can be manual, semi-automatic or completely automatic. One type of machine, which is still commonly found in printing houses, can be described as follows.The fabric is first glued to a moving endless belt. A stationary screen at the front of the machine, is lowered onto the area that has to be printed and the printing paste is wiped with a squeegee. Afterwards the belt, withthe fabric glued on it, is advanced to the pattern-repeat point and the screen is lowered again. The printed fabric moves forward step by step and passes through a dryer. The machine prints only one color at a time. When the first color is printed on the whole length ofthe fabric, the dried fabric is ready for the second cycle and so on until the pattern is completed.
In other fully mechanized machines all the colors are printed at the same time. A number of stationary screens (from 8 to 12, but some machines are equipped with up to 24 different screens) are placed along the printing machine. The screens are simultaneously lifted, while the textile, which is glued to a moving endless rubber belt, is advanced to the pattern-repeat point. Then the screens are lowered again and the paste is squeezed through the screens ontothe fabric. The printed material moves forward one frame at each application and as it leaves the last frame it is finally dried and it is ready for fixation.
In both machines the continuous rubber belt, after pulling away the fabric, is moved downward in continuous mode over a guide roller and washed with water and rotating brushes to remove the printing paste residues and the glue, if necessary. After this, the belt is sent back to the gluing device. In some cases the glue is applied in liquid form by a squeegee, while in other machines the belts are pre-coated with thermoplastic glues. In this case thetextile is heated and then it is squeezed by a roller or simply pressed against the rubber-coated belt, causing the glue to soften and instantly adhere.
After printing, the screens and the application system are washed out. It is common practice to squeeze the color from the screens back into the printing paste mixing containers before washing them