Traditionally, membrane overlays are screen printed. Screen printing or silkscreen, also known as Serigraphy, was invented in China during the Song Dynasty (960-1279 AD) where silk was used to make screens. Screen printing is considered the most versatile of all the printing methods and works well for certain jobs and will always have its place in modern printing facilities. It’s important to have both tools in the tool box and know when and where to use it.
One drawback to screen printing is the cost for each addition color. Every color adds considerable extra cost. Digital printing works with 4 color process (CYMK) therefore once the 4 colors are achieved all additional colors after are at no cost. Designers today want lots of colors and special effects in their artwork, including gradients, shadow effect and detailed logos. Screen printing cannot easily achieve the desired effects as the digital process can.
Only recently has the technology been available and press cost aligned to make digital printing an option for screen printers. Membrane overlays are made of chemically resistant plastics which is why they are popular in industries like Medical devices and outdoor applications such as gas pumps. This same resistance to environmental attack makes it a challenge for the inks to adhere properly to the plastics as well. Digital printing solutions have been limited up to now and have included UV inkjet and sublimation transfer. UV inkjet is slow at best for the quality level required and sublimation requires too much heat for the transfer process causing material distortion.
The Indigo printing process uses 4 color (CYMK) printing process.
The operator sends a file to the printer and the software separates the incoming data to different plates. The printing plates are temporary and magnetically attract the ink which is electrical charged. The Indigo printer makes a new electronic plate for each print and is recreated after each print. The plate transfers very small inks dots of the 4 colors. When all the colors are printed in the correct order and orientation, the final image is created. This process can simulate a screen printed solid color or can print a photographic type image. The 4 color gamut can print thousands of colors.
Indigo sheet sizes are limited to 13 x 19, 12 x 18 being the standard and media thickness cannot exceed 15 mils. The Indigo cannot print metals at this time due to the magnetic nature of the printing process.
The HP Indigo printing technology is one of the fastest growing digital technologies in the market offering an offset like quality based on an electro-photographic (laser) printing process.
Do you limit the visual design of your graphic overlays because of printing capabilities that are available to you? What can you do with Digital Printing? Would it help you with your product’s presentations in the market place?
We’d love to hear your thoughts!