Proofing

mstewart

Member
Does anyone have or know of a good definition of a contract proof? We colour manage an Indigo Press for our proofing. We proof for printers worldwide; usually on their supplied stock. Some printers will put a loop to the proof and see 'dots' on the proof that are not in the file and then all production stops until we try to explain the colour management process of creating a proof.
 

SteveSuffRIT

Well-known member
On a digital production printer, a quantity of one (1) is a contract proof because its the uses the same device/conditions/settings that will be used later for the larger production quantities.
We should NOT evaluate or judge color through a magnifier (loupe). This should be done at normal viewing distances of ~18".
The loupe is only used for troubleshooting and problem solving to investigate why there is a noticeable difference between proof & press.
A "contract" proof sets the expectation (target aim) for the color. Of course, it should also be "matchable". Then next, the conversation may be about color accuracy, uniformity, and consistency.
Are you making proofs for other printers (who should know better) or for customers (who may need education)?
Steve Suffoletto
 

mstewart

Member
We are making proofs for the printer on printer supplied stock. Each proof has the three tiered Idealliance colour bar printed as well. When measured the colour bar 'Passes' when measured against Gracol 2013 or when measured against Fogra 39. We also proof uncoated. The colour bar is there for the printer to measure for colour accuracy for they print specification they say they print to. The problem comes with light tints. the printer will use a loop and see a slight 'dot' of magenta in a 20% yellow tint. At that point in time they will halt production and say they will not be able to match our proof as there is magenta in the yellow. Indigo yellow ink is not quite the same as ISO 2846, hence the colour management and hence the slight bit of magenta in the yellow.

I'm trying to find a definition I had years ago for a contract proof. It stated that a contract proof was a 'simulation ........' and I can't remember the rest.
 

gordo

Well-known member
On a digital production printer, a quantity of one (1) is a contract proof because its the uses the same device/conditions/settings that will be used later for the larger production quantities.
That assumes that the OP is using their Indigo Press to proof for other Indigo Presses. The OP may be proofing for a completely different type of press.
 

mstewart

Member
Gordo - you are correct. The Indigo is being used to proof for offset printing, sheetfed, web (both cold and heatset) and UV presses. On another note - how are you enjoying the weather out your way - from one canuck to another.
 

Puch

Well-known member
Back in the old days when inkjet proofs were catching up, we had the same problem at the print room. "What are these dots in the yellow, cyan?" But eventually pressmen started to realize that the color was indeed good, no matter how it was constructed. As Steve Suffoletto said, proofs are meant to be evaluated with the naked eye, from 30-50 centimeters. If the certification is "passed", they can stop complaining and can try to adjust the machines to match the proofs' color. A loupe is a tool to check registration and other press parameters, but not color.
 

gordo

Well-known member
Gordo - you are correct. The Indigo is being used to proof for offset printing, sheetfed, web (both cold and heatset) and UV presses. On another note - how are you enjoying the weather out your way - from one canuck to another.
The primary functions of a contract proof are to set expectations for the final presswork and to mitigate liability if the presswork.
The only true proof of final presswork is a press proof (a.k.a. wet proof) done by the same press and target substrate that will be used for the final job. Anything else is a compromise. The less the proofing system has in common with the actual production of the job the greater the risk and hence potential for failure. The (signed off) contract proof and stated expectation qualifiers mitigate liability. The classic example of this is an inkjet proof that does not show the subject moiré that appears in the final presswork. The customer may reject the job (and payment) even though they signed off on the proof)
Never use the term "match" when it comes to proof and presswork - it's too absolute a term. Use "align" instead. It allows for some wiggle room.

RE: your question - Here on the wet coast we have white fluffy stuff falling from sky. Unusual for us. Lasts maybe a week each year. The view from my backyard.
Backyard.jpeg
 
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narseman

Active member
We are making proofs for the printer on printer supplied stock. Each proof has the three tiered Idealliance colour bar printed as well. When measured the colour bar 'Passes' when measured against Gracol 2013 or when measured against Fogra 39. We also proof uncoated. The colour bar is there for the printer to measure for colour accuracy for they print specification they say they print to. The problem comes with light tints. the printer will use a loop and see a slight 'dot' of magenta in a 20% yellow tint. At that point in time they will halt production and say they will not be able to match our proof as there is magenta in the yellow. Indigo yellow ink is not quite the same as ISO 2846, hence the colour management and hence the slight bit of magenta in the yellow.

I'm trying to find a definition I had years ago for a contract proof. It stated that a contract proof was a 'simulation ........' and I can't remember the rest.
I found this... "A hard proof (sometimes called a proof print or match print) is a printed simulation of what your final output on a printing press will look like. A hard proof is produced on an output device that’s less expensive than a printing press."
Does that help? (Print a hard proof)
 

mstewart

Member
Narseman - This works - I can massage it a bit. Thanks

Gordo: I am well aware of 'Wet Proofs'. Unfortunately the ones we have come across have been made on a specific system, almost like a silkscreen system and they have been absolutely hopeless. I don't think we have ever seen a 'Wet Proof' come off the actual press that would be printing the job - using the same plates, etc. At least I haven't seen one in about 30 years. Your notes on proofing are helpful in what I intend to put together. Now I just have to hammer 'align' into the sales department as I cringe every time I hear 'match'. Thank you.
 

gordo

Well-known member
Narseman - This works - I can massage it a bit. Thanks

Gordo: I am well aware of 'Wet Proofs'. Unfortunately the ones we have come across have been made on a specific system, almost like a silkscreen system and they have been absolutely hopeless. I don't think we have ever seen a 'Wet Proof' come off the actual press that would be printing the job - using the same plates, etc. At least I haven't seen one in about 30 years. Your notes on proofing are helpful in what I intend to put together. Now I just have to hammer 'align' into the sales department as I cringe every time I hear 'match'. Thank you.
I've seen wet proofs being used in China and Malaysia for printing for N American buyers. I agree they're not as much used as once they were.
One thing to note - all the posters on this thread talk about proofing color. However, although important, that's not the only thing a contract proof is used for. You're also looking for moiré (subject and screening), ribboning, sawtoothing, missing graphics, font swaps, bitmapped fonts, the list goes on and on. Some printshops affix a tag to their proofs where the customer signs it off that succinctly explains what the proof is used for and what its limitations are. Although it's good that you include color bars for clients to measure note that there can be a wide variance in measuring instruments. The proofs may pass with your instrument but not your client's. Also, they should be made made aware of the importance of the lighting conditions under which the proof should be evaluated, especially as regards the OBA issue, and especially when proof and presswork are directly compared. I've seen printshops that use regular office fluorescent tubes in their light booths instead of the correct ISO specified bulbs.
Most folks haven't a clue why they're looking at proofs or presswork under a loupe. If you see a customer doing this it's worth asking them what they're looking for.
 

mstewart

Member
Yes - the proof we supply is more than just colour - graphics, fonts, trapping, moire, etc. are all looked at. When we read the colour bars and sometimes a P2P we always supply the verification process print report which states, among many other items; spectrophotometer used settings used, M0, M1, etc., print target. We do this because we do run into differing results when a printer reads the same P2P or colour bar. Once we receive their report, there is inevitably a difference in settings; mostly M0 versus M1 or △76, △00. Every bit of this keeps us on our toes. OBA's are taken care of in ORIS Press Matcher where new proofing templates are created to deal with specific papers and the the amount of OBA's in those papers. For the past 5 years or so we have been doing very well but occasionally we run into the 'loop scrutiny' of light tints and that's where we have a communication issue.
 

Repro_Pro

Well-known member
In my experience from overseeing printing on Indigo Presses, there are instability issues with very light pastel colors (tints of 5% and less).
BTW, I had to re-read several times until it struck me I should read "loupe" in order to understand "loop"...
 

mstewart

Member
Thanks for the spelling update ; )
Light pastels can be an issue; but with proper press maintenance can be maintained. We haven't had too many issues with very light tints.
 

gordo

Well-known member
Just a sidebar about pastels...
The affect of OBAs in paper are most pronounced in pastels and as a result can lead to what appears to be a press problem. This is because ink blocks the affect of UV in the viewing light and, since there is little ink on the paper in pastels, the impact of OBAs is strongest in those areas. This is true for any print process - digital or not - where the substrate contains OBAs.
 

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