Printing on Synthetic Substrates and Foil

[Cold]

Hello all,

I've seen a few topics on the forum regarding printing on synthetic substrates so I thought I'd share my suggestions based on my own experience and the recomendations I've been exposed to. Please feel free to add to or dispute the information below based on your own experience.

Cheers,


Cold

Conventional Off-set Printing
on Synthetic Stocks


1. Stock handling.
A. Carefully read the technical data sheet provided by the manufacturer.
B. Many synthetic stock manufacturers suggest that the stock be allowed to
sit in the press room for 24 hours prior to printing. Many also suggest not to
open sealed stock until within 4 hours of press time.
C. Some synthetic stocks are more susceptible to distortion than others. Take care in planning when fit is crucial.
D. Static electricity can be a real nuisance, prepare accordingly.
E. Dyne Level testing, if you have the ability to test the surface tension I
recommend a dyne level between 40 and 46.

2. Inks
A. High solids, fully oxidizable inks should be used.
B. Ink should be tested for suitability on each stock.
1. Flexible Vinyl - It is optimal to test inks on each lot of stock to
eliminate any issues that may arise from variations.
2. The printer may request that a co-ship sample of the ordered
stock be sent to their ink manufacturer.
C. It is suggested that graphics not exceed 220% due to slow drying issues.
D. Wind the sheets after 6-8 hours
E. Allow 24-72 hours for curing purposes before handling after the last side
has been printed.

3. Fountain Chemistry
A. Ensure that the chemistry is fresh and properly mixed to the manufacturer’s
specifications.
B. Run as little water as possible. The more water that is run, the more the
inks’ drying will be retarded.
C. Use Alcohol in place of alcohol substitute, if possible.

4. Lifts
A. Run short lifts. 250 sheet max. The shorter the lift the better air flow to
the press sheet, which will assist the inks in drying and preventing offsetting.

5. Spray Powder
A. Use larger micron powder >50 microns to help prevent offsetting.
B. It may be necessary to dust sheets when dry, prior to coating.

6. Load Temperature
A. Obtain proper load temps from stock manufacturer. (Beware heat and
plasticizers).

7. Coating
A. Ensure that coating being used is suitable for synthetic stock.

[Asures]

Don't forget to check the Dyne level of your stock!

You should be aiming for a 38 or above.

[Cold]

Don't forget to check the Dyne level of your stock!

You should be aiming for a 38 or above.

Absolutely. I have that under stock handling.

[Asures]

You're right, my bad. I missed that.

Sounds like you got it under control..

[DrummondAW]

One important thing I did not see is checking the underside of the sheet while printing with substrates that are prone to high levels of static (I do see you mentioned static, but I do not see the following reason addressed). The reason being that it will often times pick up any particles of dirt that is in the press. Those particles can then transfer to the printed side of the substrate during a run, or severely affect the printing of a two-sided job.

[herbert]

Hi all

Hopefully you can help on this subject.

We currently have a production Problem, here goes

Material trucard single sided Board 240gsm
Inks - Heidelberg Saphira UV ink
Foil - Pillows of Light From API Foils (Holographic Foil)

We have a Problem with the Ink Adhesion to the foil. Ink is Flaking off when folding. (Especially where there is a crease)

Can anyone explain why this would happen. We used the dyne test pen 38 and the foil is reticulating. is this correct?

Can anyone help on this matter or offer any advice, also are therer any quality procedures to stop this expensive problem happening again.

[Cold]

Hello Herbert,

I see two potential issues from the information you posted:

1. The dyne level should be higher than 38 at a bare minimum. If the 38 pen is reticulating on your foil(assuming test and pen are accurate), then in my opinion, this is not an optimal surface to print UV on. It may be that the corona treatment on this board was done too long ago and has since dissipated. A call to the foil supplier should be helpful in identifying if this stock needs replacing.

2. I am not familiar with the Saphira UV inks. Please verify from your supplier that this series is suitable for synthetic substrates, specifically specialty coated foil. It may be that the ink is not elastic enough for this substrate.


I hope this is helpful.


Cold

[Corey]

With these materials, you have to remove static from BOTH sides of the substrate, before it touches the machine. A common misconception is that you just have to remove it from one side by spraying it with anti-static spray or using those useless ionizing blowers.

There's a video of a Mimaki engineer who stretches an anti-static elastic cord, across the material before it enters the machine. This cord is placed on both sides of the machine. This is ideal for these types of materials and a good practice for printing on synthetic substrates and foils.

Here's the video. Pretty interesting set up this Mimaki engineer is using:
YouTube - Solving Printing Defects on Roll to Roll Printers - Static Eliminators

Good luck....!

[Steve Werner]

Cold, looks like you've got it covered. With fountain solution I would make sure that it's fresh, around 4.0 pH and at the manufacturers recommended conductivity for your mix proportions. I highly recommend ionized air bars on the press if it doesn't have them as well as using a static string that's properly grounded ( not tinsel but string ). Dyne levels will vary based on the material being printed but a minimum of 38 is always a good thing. Most rigid vinyls are going to run around a 42 dyne and styrene around 50 dyne. There is a product out there called Speedy Dry which alot of pressman swear by for printing on plastic, might also be a product worth looking into. Herbert, are you printing directly to the foil or is it an acrylic or vinyl coated product ? Sometimes holographic products are films and not foils.

[Steve Werner]

Just one more thing ( the old Columbo line ), in winter especially make sure you've got a decent humidity level or you will have so much static it won't matter what you do to knock it down it will wreak havoc.