Digital Printing The Right Way
Digital Printing The Right Way!
Relative humidity and temperature control might be one those issues in a printing company (both traditional and digital) that almost nobody knows about, but that can have a big influence on the production.
A couple of recent examples from companies with problems:
- One is working within extremely tight tolerances, less than a delta E of 1 (they are in very specific and demanding niche). But they had colour issues, to get reprints exactly the same as previous orders (almost all of their orders are reprints). The doors were open… “Yes, we have to do that, otherwise it gets too hot in here.” It was summer and the outside air was also quite hot and very dry.
- Another one is also dealing with a lot of reprints (but not the tight tolerances as the previous example). They deal with many ‘professional print buyers’ who are very picky on colour. So from time to time they get complaints that a new production run doesn’t resemble the old one close enough. Next to more obvious variables in the printing process: in winter time they print at 15°C, in summer time sometimes even over 30°C.
Having a relative humidity control / temperature control (air conditioning) in a printing room can be expensive but it will definitely make your production environment more stable. This will pay for itself in next to no time (less setup waste, less rejected jobs, less reruns equals bigger profits). Printers who have invested in air conditioning all love it! And one extra advantage: it’s also more comfortable for the press operators…
In the world of digital ink jet printing, there are many variables to achieving quality output. These different Variables can extremely affect the way printers function and inks lay onto media. Below are basic Recommendations for achieving optimal print quality.
Print room should be a clean, well ventilated, temperature and humidity controlled room. It should be in an Enclosed area away from direct sunlight. This will keep the printer and more importantly the print heads away from dirt, you should also dust off the media prior to printing. Gloves are recommended for handling the media as to keep fingerprints and oil from your hands off of the printed surface. Recommended relative humidity: 40-60% (less than 30% and more than 80% humidity will give you problems) Recommended temperature: 21-24° C (less than 18 and more the 28 will give you issues) All rolls of media should be stored in the press room for 48 hours prior to printing to adjust to the correct environment.
Having a controlled room also helps control static. Static can really affect ink lay down, create stray dots (similar to overspray) and attract dust towards the media and printing area. Avoid carpet or rugs in the printing area, these attract static. Static also thrives in low humidity environments. Static string is a relatively inexpensive way to help control static. You can find it at www.hitecink.com Apply the string to a metal piece of the printer (good to loosen a screw and tighten back). Then run across the web width of the media one inch away. Again, apply the other end of string to a metal piece of the printer and ground to the floor. Grounding to something away from the printer is important.
Using the proper profiles is the key to optimal printing. This includes proper heat settings, ink restrictions,Linearization, total ink limits and ICC profile. Without these correct profiles, the media will not print properly! Profiles will control output, increase production time and reduce ink usage (saving you money). Talk to your Media supplier about what profile should be used, Generally Media supply companies provide profiles for their media. A custom made profile can be made to suit your individual requirements,
Contact email@example.com for addition profile advice.
Follow all printer manufacturers’ guidelines for printer maintenance. Proper maintenance will ensure correct. Calibration and increase the life of the printer, print heads and mechanical parts (saving you money).
You must let printed graphics dry properly. Dry to the touch does not mean that the printed graphics are Completely dry or “cured”. The graphics must be accessible to the air to drive the solvents off of the media. Printing directly onto a take up roll and putting in the corner is not drying. There must be air flow to push the solvents off the media! We recommend 24-48 hours dry time before any type of finishing (over laminate or clear coat). Without the recommended dry time, solvents are trapped and migrate into the film causing it to soften and stretch improperly. These solvents will also migrate into and deaden the adhesive. We cannot stress enough the importance of drying the graphics properly. Latex printers are supper critical about using the correct profile to make sure the ink is cured, these can rewet and delaminate.
Follow these recommendations to control these variables in your printing process and you will be on your way to better controlled output, happier customers and an increased bottom line.