How to make glow in the dark screen printing?

 Photoluminescent pigment or glow in the dark powder is strontium aluminate long afterglow luminous powder. It can absorb light energy for 5-20 minutes under sunlight or lamp, then store it in the crystal lattice. In a dark environment, it emits an afterglow for 8-10 hours. Moreover, the afterglow lasts more than 70 hours for the luminous intensity decays to the lower limit of human eye observation (0.32mcd/m2). This material's chemical properties are stable; the process of light absorption, storage, and glow can repeat for unlimited times. The life span is more than 20 years. It is non-toxic, eliminates repetition, and produces no harmful substances during the production process.

The glow in the dark powder can be added into the screen printing technology for many different applications to enhance artistic and safety performance, such as the pattern on the mugs, the signs on the signage, and the design on the clothes.

However, how to choose the right type of luminous powder, which kind of printing paste to apply, what to do to reach the best glow effect? These technical problems sometimes are challenging to solve. Today, we will talk about these issues from different aspects.

1.Printing Ink:

Ø The ink used in luminous printing is a glow in the dark containing photoluminescence pigment, organic resins, organic solvents, and additives in a particular proportion through a unique process.

Ø The higher the transparency of the ink, the better the glow effect. To protect the glow pigment's brightness, it should add into neutral or weakly alkaline transparent resin.

Ø The viscosity of the processed luminescent ink is about 300-500mPa.S. When printing, the printing speed should be slow, and the ink viscosity should be adjusted with the thinner to meet the printing requirements. Choose high-viscosity resin, and add an anti-settling agent to prevent precipitation.

Ø According to different printing materials, choose different types of transparent ink, such as select metal-specific inks for printing on metal materials, and page on PVC materials, choose PVC-specific inks for better firmness.

Ø Because the particle size of the luminous powder used for screen printing is usually more significant than that of ordinary color pigments, a more robust binder is needed to fix the color. Especially when it applies to the screen printing of glow clothes, if the adhesive quality is insufficient, the uniforms will quickly lose their glow effect after washing many times.

2.Glow In The Dark Pigment:

Ø When screen printing, the choice of luminous powder is critical. The particle size of the glow powder depends on the mesh's size, and it must be smaller than the size of the mesh. If the luminous powder is too big, the mesh will be blocked and cannot be printed, which will affect the printing effect.

Here is an example, if the size of the mesh is 200 mesh, then the 250-400mesh luminous powder is recommended. Because the glow powder's size is an average value, 200 mesh glow powder, the average particle size is between 50-60micron, but the maximum particle size may exceed 60micron. During screen printing, the bigger particle size will block the mesh.

When making signs and print clothes patterns, the screens used are generally 80 mesh and 120 mesh. Do not use very fine meshes; otherwise, the luminous powder cannot pass through the mesh, and the product brightness is not excellent.

Ø In the water-based ink uses water-proof glow powder. The luminous powder itself is not water-proof; it will hydrolyze in contact with water, become oxidized after a long time, and change into a white powder raw materials, and losing the luminous effect.

Ø The adding ratio of luminous powder: generally 30%-50% of the total weight, the amount of glow pigment is determined according to the printed objects' brightness requirements. The higher the pigment content, the higher the luminous brightness of the products printed with it, and the longer the afterglow time.

3.Others:

Ø When making screen printing, it is best to make luminous ink on a white background and use the bottom layer's reflective effect to improve the luminous brightness and the afterglow time of the glow pattern or logo. If the background color is not white or light, then print a white background color on the base surface.

If the brightness of the white fabric luminescent printing is 100, the dark fabric printing's brightness will be below 80. The main reason is that white or light-colored fabrics have a more durable light reflection effect than dark-colored fabrics, and dark colors will absorb some light from luminescent materials.

Ø When performing luminous screen printing, it is best not to add other colors of pigment. Other pigments will cover the glow pigments, prevent them from absorbing and emitting light, and affect the luminous effect. If adding other dye, it recommends adding fluorescent colors, which will reduce the impact on brightness.

Ø Adjusting the viscosity of the glow in the dark printing paste, to control the minimum film thickness of the luminescent layer on fabrics, and a reasonable printing film thickness should be no less than 100 microns, preferably about 130 microns. For this reason, use a thick plate rubber to ensure the thickness of the film and achieve the best luminous effect.

To having a super-brightness printing effect, choose a professional manufacturer of long afterglow luminous powder to ensure the quality and get some professional technical support.