Application of LS117 Densitometer in Screen Printing Industry

Screen printing mainly refers to using a screen as a substrate to print ink on a carrier by a photosensitive plate-making method. Printing ink into pictures or text is usually used for decoration. If ink is printed on glass then this glass is called silk screen glass. Screen printing glass is widely used, such as refrigerator doors. Screen printing glass usually needs to be measured with an densitometer.

1.What is screen printing

  Screen printing is a printing technique where a mesh is used to transfer ink onto a substrate, except in areas made impermeable to the ink by a blocking stencil. A blade or squeegee is moved across the screen to fill the open mesh apertures with ink, and a reverse stroke then causes the screen to touch the substrate momentarily along a line of contact. This causes the ink to wet the substrate and be pulled out of the mesh apertures as the screen springs back after the blade has passed. One color is printed at a time, so several screens can be used to produce a multicoloured image or design. (quoted from wikipidea)

2.Making method and application of screen printing

(1) Direct plate making method of screen printing

The direct method is to lay the light film of the wrist film coated with the photosensitive material on the work surface and place the stretched wrist net frame on the film base. Put the screen frame on the photosensitive paste and apply it under pressure. After natural drying, it is cured with ultraviolet rays. After the screen is dried, a screen printing screen can be produced. After drying, use the translucent material for densitometer detection. After drying, we can use the desitometer to detect the transmittance and optical density value of the translucent material.

(2) Indirect plate making method of screen printing

The method of indirect plate making is to expose the indirect film first and then peel off the negative film after warm water development and drying. When making a plate, the film surface of the graphic film is tightly adhered to the stretched screen. The film is compacted with the wet screen by pressing and the film base is peeled off. Finally, the screen printing screen is made by air drying.

 3. Measure the light transmittance and optical density value of screen printing screen with Linshang LS117 densitometer

   The light source of the Linshang LS117 densitometer is 380nm-760nm, which conforms to the CIE photopic luminosity function. The densitometer adopt the diffuse transmission principle. It is a high-precision densitometer with an integrating sphere effect. Its transmittance measurement accuracy is ± 1% (0% --- 50%), ± 2% (50% --- 100%), optical density measurement accuracy is ± 0.02 (0 --- 2.00 OD), ± 2% (2.00 --- 6.00 OD). The instrument has the following characteristics:
●High measurement accuracy and wide range, the optical density value can be measured to OD6.
●Measurement for both optical density value and the light transmittance.
●The LS117 densitometer uses a diffuse transmission light path design and also has an integrating sphere effect.
●The densitometer has passed the test of the Chinese Metrology Institute, and the light source conforms to the CIE photopic luminosity function.
     Linshang LS117 densitometer has two measurement methods, fixed base measurement and handheld measurement. The fixed base measurement is more suitable for small-sized objects and the handheld measurement is suitable for large-sized or irregular objects. The figure above showed the fixed base measurement method. It can be seen that the measured transmittance of the mobile phone cover ink is 0.5863% and the optical density is 2.264. For hand-held measurement mode, please read "How to Choose lampshade Advanced Light Transmittance Meter?"