In my printing experience, the ink and water balance measurement has always been a feel thing. It wasn't hard to tell if an ink was behaving properly just based on my experience and instinct.
I was soon introduced to a method of actually measuring the window that gave me a tangible number. This allowed our pressroom in a number of ways:
- comparing different ink brands
- keeping historical accounts of the same brand
- tracking quality
This method, I can assure you will work for any press, web or sheetfed. So here it is:
1. At a specific running speed, get a water reading at the bottom of the window. This means, run the absolute minimum amount of water until the product is about to scum. At that point take a reading on the dial you use to adjust your water. Or it could be a reading on the motor itself. It's not really important where you take it from. The main thing is that the number represents a reading from the water motor speed. We'll call this number Y.
2. Now bring the water up until the point where you are just about to start losing density. That is, up to it's maximum. That's right, the top of the window. Again, take a measurement. We'll call it X.
3. Do the math. Take X-Y and divide it by X+Y. This will give you a fraction. Multiply it by 100 and you have your number. Make a record of it and use it to compare.
Thought there have been many articles that speak about what makes an ink water balance stable, as of yet, I still have not seen anything more practical to use in the pressroom from GATF or anyone else, so if you are looking for something simple and easy to compare, this formula may work for you. If you have better ideas, leave your comment below.