Screen printing on GLASS – A Key Process!
It's hard to believe that a glass maker, no matter what their speciality is (automobile, cosmetic, architectural packaging, household appliances with curved or flat glass), it is often judged by the quality of the printing rather than the core initial product, the glass itself.
The image, and therefore the printing, becomes a critical key element.
Global standards, requirements and expectations are increasingly high and require discipline, excellence and standardisation in the screen printing process. I have met many glass-makers from all over the world, engaged in many activities.
I have to say that manufacturers who have neglected screen making have met some real obstacles. The screen making laboratory laboratory is often screen printing’s poor cousin.
Unskilled printing is sometimes synonymous with poor quality in the finished product. Now that takes the biscuit! But it's a reality. Screen printing on glass is not just an artistic process à la Andy Warhol, but mostly an industrial printing process with its methods and procedures that require discipline.
Two factors are intrinsically connected: Quality printing and repeatability.
It is a shame to find that screen printing know-how is generally in decline, mostly due to the lack of training, innovation and the limited interest that our craft inspires in the younger generation.
The curves intersect: demand is increasingly exacting, and print masters do not pass on their know-how and are not very innovative.
We should raise awareness, however: screen printing on glass deserves better, because it is the only process that achieves special effects, ink thickness and printing consistency with high productivity requirements.
Whatever our involvement in the process, excellence is everyone's business.
To me, the quality of the screen is essential.
It is very important to control ink deposit in microns, to achieve great detail from the first to the last print.
The screen becomes a strategic element
Indeed, multiple printing factors, such as machine settings, rheology of enamels or organic inks, IR, UV, pigments, squeegee, squeegee pressure and angle, will never achieve satisfactory results if the screen is neglected.
For these reasons, it is imperative to know and master the tools available to printers.
- There are many types of fabric
Polyester, Polyamide (nylon) fabrics, dyed yellow, white, plasma-treated, metalized polyester, stainless steel.
The question is: which fabric should we choose? Ink deposit is determined by thread diameter.
Example: PE AM HI GLASS 77 48 PW fabric versus PE AM HI GLASS 77 55 PW fabric
PE AM HI GLASS 77 48 PW = 77 threads per cm with 48 micron thread and a mesh opening of 36% theoretical deposit 31.7 cm3/m2
PE AM HI GLASS 77 55 PW = 77 threads per cm with 55 micron thread and a mesh opening of 28% theoretical deposit 25.8 cm3/m2
An identical number of threads per centimetre yields a different deposit.
Furthermore, plasma surface treatments increase the longevity of the screen and promote passage of the ink through the mesh;
What machine should be used, what is the fabric breaking point? What is "elastic memory", why is it important to know the thread count before following tensioning?
Should we take into account the solid content of the emulsion, as it influences the final dry deposit: rheology, viscosity, diazo system, Dual Cure, triple cure or pure photopolymer, according to REACH standards?
Coating must be controlled using an automatic coating machine, or capillary films
- Stencil Imaging
Traditional with film or engraving with a DLE/CTS machine: the choice of the DPI?
So many important questions need to be addressed in order to create a screen.
This is why Saati endeavors to answer your concerns and stand behind you in your expertise. A top notch result is our goal business. Our goal is to give you the components for a perfect screen.
As a manufacturer of fabrics and chemical lines, we have the expertise, the complete stencil for an excellent result. Our staff and I are at your disposal to enhance your performance.
Don't hesitate to contact us and discover our new HI GLASS fabric and our new HRX emulsion specially developed for a screen made for printing on glass.
13.11.2015, Saati SPAprint
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