Flash Strikes Again!

Troubleshooting a problem at a customer’s print shop is part of our sales managers’ or print production manager’s repertoire.  We’ve asked Kieth Stevens, our Western Regional Sales Manager, to share one of his recent experiences:

 “Things are tough out there!

 If you find that your whites (inks, that is) don't flash fast enough, have patience – you may be over-flashing the ink.

 I often get calls regarding the flash times of any one of our white inks. Usually, it’s a white that I know flashes quickly.  (A flash cure unit is used during production to cure the surface of the ink only.   This allows subsequent colors to be printed on top of a white underbase for example, as it is in this case.   Fast flash times for inks are important as it speeds up the production process).

 I scratch my head for a moment and think.  Then I ask the customer a few questions:  Are they using an IR (Infra-red) flash or a quartz unit?  What is the distance from the heat source to the substrate?  What is the flash time they used?  What is the temperature set at?  Do they have a cool down station?  And of course:  Which white ink are they using?

 Recently, I was asked to visit a shop that had a problem with one of our whites that previously had been performing well.  According to the customer, the ink now was not flashing as fast.  Prior to making the appointment to visit the shop, I asked the usual questions and was left scratching my head again saying to myself that something didn't add up.

 I went ahead and visited the customer, whom I knew very well and also knew that they do great work.  First I asked the ink supervisor if they had a cool-down station after the flash station and he assured me that they did.  I asked him how long of a period they were flashing and he informed me that they had to increase the flash time up to 8 seconds – which is a long time for normal print production - so I said: ‘Whoooh. That's too long.  Are you sure you’re not over-flashing?’  ‘Oh no,’ they said, everything was right-on production-wise, so it must be the product:  The same container of product that was working well previously on another job…Hmmm.

 Well, after talking with the actual press manager, I found out that they were in fact not using a cool-down station.  But because they found the ink sticking to the screen at the next print station, they added another flash to get it to flash faster.  What they didn't know is that the ink was, in fact, over-flashed and actually needed LESS flashing time.   When an ink is over-flashed, it liquefies or melts due to the excessive heat rather than hardens as it should when the ink surface is cured.   That is why the ink was sticky after flashing.

 What People need to keep in mind is that the press is cold in the morning but after running the machine for several hours, the platen starts to warm up.  In fact, it can get very hot.  So the flash time and/or temperature setting should actually be reduced to have the same results as when the machine was run in the morning.

 I know it’s tough out there, so call your supplier and have them work with you to help troubleshoot any production problems. You're not alone!”

 For more on International Coatings’inks visit our website or our Product Bulletin page.