There is no such thing as a perfect ink mixing system (or even a really good mixing system).  Formulas are often inaccurate by several shades (yes, I’ve experienced this consistently across several mixing systems and it is not for lack of a high-end scale).  So what do you do when you know a color will not pass in-house QC or customer approval?  Most shops will modify the formula or simply adjust the mix by eye.  This creates a BIG problem with repeatability in your shop.  Honestly, can you rely on your ink-smith’s record keeping skills enough so that you trust that every modified formula has been properly documented?  If adjusting by eye, do you trust that all parties in your shop have the same eye for color?  Of course not, but in the midst of a busy production day, when you just need to get the job off your press, expediency wins.  Don’t let this happen!  It is a trap that seemingly all printers fall into, including myself.  After years of acquiescing to expediency our ink inventory, heavily modified without documentation, had become such a burden on production that we decided to decommission it.  The old inventory (tens of thousands of dollars worth of ink) was palletized and placed on racks where is rests today (another problem in and of itself).

Time for a fresh start.  When we moved into a new facility in 2012 we started mixing a new ink inventory.  Today, this is how we handle an inaccurate mix:

1. To be fair to the manufacturerWe’ve established a one-shade, up or down, tolerance for all ink mixes (in the bucket, not on the shirt)
2. If a formula is off by more than a shade we set the mix aside and request a new formula from the manufacturer (amazingly the revised formulas are almost always perfectly accurate, why can’t/don’t they do that the first time???)
3. If we do not have time to wait for a new formula we substitute with another similar color from inventory or mix a similar formula (which is hopefully accurate)
4. We’ve arranged a buy-back program with our supplier for the inaccurate mixes.  To do this we had to convince them that the accuracy issues were in the formulas and not “operator error”.  It wasn’t easy, but it was worth it.

The whole point of an ink mixing formula is to provide accuracy, repeatability, and a level of ease in your ink department.  Modifying colors over time will create nothing but a headache and, well, maybe a little job security for you “expert” ink-smith who knows or thinks he/she knows how to modify every color just right.

Don’t let this happen!