Material Testing Best Practices

[Newtothezoo]

I know UV printing is challenging at best, but we can't seem to find the right help in making the process a little more smooth.
Challenges are: ink / water balance. We have tried several inks and fountain solutions, had vendors in many times.

Printing on non paper substrates. This is where I really need guidance. We have been burned many times with taking a job on a material and getting to press and something not working. Have one right now where ink is not adhering. Very costly and time consuming.
Can anyone share with me some best practices on handling these jobs from inception to delivery.


Thanks in advance.

 

[ThePrinter]

The proper way is to do a drawdown of the ink on the actual substrate. Typically, different inks are used on plastics vs papers. If you are still having difficulty getting adhesion you can try putting down a UV coating over the top of it to give it an added layer of protection. We recently had a project where we were getting poor adhesion on foil board with plastic inks. We switched to paper inks and it ended up being a little better. After applying gloss UV coating over the top of the ink it passed the tape test.

 

[Cornishpastythighs]

I know of a printer who does not have what I would call a powerful Heidelberg UV press, he does not have interdeck lamps and only has one lamp after the last print unit plus end of press for UV after the coater. He prints on plastic and other non absorbent stocks very well. His secret was to develop a really good primacote that he applies on a seperate pass through a print deck to give him 100% adhesion when he prints his inks. It means 2 passes but his inks stick like glue. Just a suggestion.

 

[turbotom1052]

id recomend only buying a substrate contingent on its recent corona treatment and its passing of a dyne test.

 

[jonprintz]

You need to begin an approved stock list that document stocks that you have been successful printing on and all the variables, ink, etch, press speed, lamp age, stock, dyne level, primer needed?, what primer, what top coating, etc.

Primer is needed on certain stocks. There are several good primers available. The suppliers will be happy to take some of your stock samples to their lab and let you know which of their products works best on it. Same goes for the ink companies but a drawdown does not account for water introduction and will not be entirely accurate.

The ink company is usually willing to share the etch used by other printers using their inks with good results. We have found that running consistent conductivity levels is crucial.

Adding coating may help pass an adhesion test but is only masking a problem that may come back to you later. It does add a layer for scratch resistance but many times ink to substrate adhesion will be less as the ink / coating bond is normally the tightest link.

Plastic inks generally work on paper very well. The opposite is not usually true in my experience.

Certain stocks are problematic even with good dyne level and primer. Some manufacturers have better quality control than others on very similar substrates. Experience is the only teacher.

Over a period of time when good documentation is maintained you will learn how to be successful with your equipment and materials.