I found this on the internet on how to measure delta E
How to interpret Delta E values.
(2–10): The difference is easily noticeable at a glance.
I wanted to place the measurable value around 4. The concern is if the printed envelope has consistent color throughout the entire job. We do have pantone colors that would need to match what come off of a press for logos as well.
The human eye is very subjective, and often biased or wrong since many of us have a slight color blindness, and we're effected by the surrounding lighting, etc. Going back to
@SteveSuffRIT asking if you have a device to measure this...such as a spectrophotometer, is much more reliable so you can go by the true measured numbers, and not an opinion. Based on what you typed above, it seems like you're relying on your eyes.
Back to your original question, we have the
Postmark RapidColor Pro 1170 Pro which is the same machine with a different label (they all use HP print heads)....
Would asking for Registration of print must not exceed 0.5mm be realistic?
No...due to the nature of how the blank envelopes themselves are made very inconsistent in shape and size. Also, the open conveyor belt feeding method of these machines does not allow for the most consistent positioning. There is no side guide or front grippers once it hits the final belt. Every machine has a stated positioning tolerance listed in a specification guide somewhere. I couldn't find it in the
brochure, so you'll have to ask the sales rep if they can provide that. I'm guessing it's closer to 1-1.5mm.
Would asking that Colour matching must be within 2–10 threshold using Delta E:
Again, you should ask for the specification guide that lists this information. However, I never had any expectation when we bought this machine that it's for high quality and high color accuracy. It's meant to produce decent-looking envelopes cheap and fast. If you decide you want to battle with the vendor on this point, make sure you're operating environment is perfectly within their specifications. That's the first thing they'll push back on if you're complaining about color shifting/accuracy. Furthermore, they may insist you purchase envelopes made specifically for inkjet. On our machine it states the temp and humidity must be as follows:
- Operating Temperature Range 15°C to 30°C (59°F to 86°F)
- Operating Humidity Range 15% to 80% RH (non-condensing), (20% to 80% recommended)
- Storage Temperature Range -40°C to 60°C (-40°F to 140°F)
- Non-Operating Humidity Range 10% to 90% (non-condensing)
