15% CMYK color range?

[zil.xodarap]

Hi, I'm fairly new to having products printed by a commercial printer and have found a 4-color process printer who do gang printing and say they guarantee colors to be accurate within 15%. I'm wondering how to "calculate" the range so I can see ahead of time how broad the range is. For example, if I have a CMYK color that is:
80
35
0
5
...is 15% accuracy anything in these ranges:
65-95
20-50
0-15
0-20

...? That seems like a big range. Or is there some other way they calculate 15%?

Thanks,

Liz

[jimking]

They are referring dot gain. Another words that 80% can range from 80% to 95% depending on the press, paper, operator, the weather in the building. 15% gain is pretty much the norm.

[PrintDriver]

Sometimes I think they mean visually 15%. As in, if it's close at all, you can't complain. We try to come within 5-10% of hitting a color if it's not in the easy spot-on gamut.
Usually it's a judgement call.

[budafist]

This is the problem with gang run stuff. If they make 1 card look good, the others might not.

If I were you I would print a sample and ask them to colour match. If you make a fuss about it before you start, maybe they will match the whole job to yours and the other jobs in that lay will be the ones that are 15% off.

[PrintDriver]

15% is actually a pretty wide margin because it goes both ways. Above and below (darker/lighter) than your original. If color is that important to you, I highly suggest going to a brick and mortar rather than an online gang shop.

[jimking]

15% is actually a pretty wide margin because it goes both ways. Above and below (darker/lighter) than your original. If color is that important to you, I highly suggest going to a brick and mortar rather than an online gang shop.
Pertaining to offset I disagree with the below % aspect. If a plate is output with a 80% dot, in normal situations, the press will print that 80% dot because that is what is on the plate. Those dots are not going to shrink or dissapear unless something is wrong with the offset press such as blanket packing problems etc. or a poor operator, at the helm, printing -no good color- Dots growing larger (spreading) on the sheet from the plate (dot gain) is the nature of the beast. And yes, gang runs can effect the color of different color pieces on a sheet depending how they are imposed (sometimes). A color proof should be provided by the printer especially if color is critical.

[PrintDriver]

Jim, what if the printer is digital 4-color?

[jimking]

A digital offset press which is an offset press with a ctp (computer to plate) built into it such as this Presstek http://www.presstek.com/dipresses/
Even though the description somewhat discounts ctp it is still "direct to plate" in which plates are imaged on press opposed to a stand alone ctp and fed from a roll of plates in order to deliver the image on paper. It still has dot gain, but claims it is less than average.

[zil.xodarap]

We have already had a few items printed by the company and found that there is variation in the color (the business cards were to the blue side, the post cards (using the same colors/graphics) printed to the purple side (slightly)). It's not that we need specific colors so much as I would like to be able to preview the range myself so I have an idea what to expect.

If it makes a difference, the company is GotPrint.com and we've been happy with the quality of postcards, business cards and brochures they've printed. Our last two orders are the first time we've ordered something with the same colors on two different items and our first (known) exposure to the effects of gang printing.

At this point, cost is more an issue for us than exact color; I just like knowing what I'm gonna get and couldn't figure out how to adjust a color in the software I'm using to see a 15% variation - if that's even possible...

Thanks,

Liz

[PrintDriver]

Ah, got it. For us it can go in both directions. No plates. Just spewing ink. Which also means we can get it damn close. Unfortunately it also means designers think because there are no plates, there's no problem with using 20 PMS colors.
:(

[jimking]

Ah, got it. For us it can go in both directions. No plates. Just spewing ink. Which also means we can get it damn close. Unfortunately it also means designers think because there are no plates, there's no problem with using 20 PMS colors.
:(
There are also toner based digital press such as the iGen. http://www.xerox.com/digital-printing/digital-printing-press/color-printing/Xerox-iGen3-110-90/enus.html. Good press for variable data work and the quality is decent but limited, priced around $500,000. It uses no plates, so I'm sure the dot gain is at a minimum. It could be possible on this machine to have reduced % of dot.

[steve2112]

I have a heidelberg di press and we have curves done on it about every 4 to 5 months. Color is usually consistant but it will fluctuate if not measured ever few weeks. Pressroom condition greatly affect the color on these boys and we do not guarantee exact color matching at all. It usually looks pretty good. If you are worried schedule a press ok if not get a matchprint that is comes from a professional color managed printer and it should be close.

steve