Here's a troubleshooting idea for ink that we came up with not too long ago. It is especially useful during summer months or in any hot or humid climate. You can find other ink troubleshooting advice here or check the menu on the left. But here is one that works to help with ink and water balance.
In our experience, we lose ink and water balance when running at high speeds with high humidity. When trying to achieve a proper ink and water balance, we end up scumming on the plate while emulsifying in the roller train. The window becomes so narrow because the humidity bubble around the printing unit is adding to the water supply and back tracking into the fountain. When we do a measurement of our ink and water balance window, our result is zero.
After an hour or so, or ink fountain is so waterlogged that the ink becomes useless. (This can also happen if you simply run too much water, but I assume you know what your doing and this is not the case). So here is the troubleshooting tip:
Run the fountain to a low level. In other words, calibrate your ink leveller to maintain a very low level of ink. This keeps the ink "fresher" within the fountain. It's not a solution, but your ink will resist getting waterlogged as it is more consistently getting a fresh supply.
Additionally, you may want to consult with you ink supply and inquire about your water pickup value for you ink.
I've discussed how to control this from a printing unit environment perspective in the past, but I want to bring up another tip that helps. Hope you find it useful.
Related articles:
What Causes Blanket Piling?
Ink and Water Balance Concepts
Scumming - Causes and Solutions
You can also run an air blast blowing across the apex where the ink and fountain ball meet to help evaporate the water that waterlogs the ink. This also helps keep the fountain ball from stripping and not wanting to pick up ink when you run a slow stroke on light coverage work.
ReplyDeleteincrease unit roller temp and fountain solution running temp and add more fountain solution to mix so you can run water down so it dont back feed into fountain also it keeps slip rollers clean during run. (air on fountain ball also helps but is only a bandaid not a cure)
ReplyDeleteVery helpful.
ReplyDelete