Printing films TIP:
This may be more of a RIP tip.
I recently had been asked why a 3 color file would print one of the colors out of register or (as explained to me,) stretched or distorted.
Generally, we all will print all seps at once, (having the file open and printing to film) and completing that task before closing out of the file. If using a CTS/DTS, we will move the file to a transfer folder for a RIP (one time). Then we close out of that file and move to the next job. If, by chance, you need to open the file again to revise a color and you only print out that one color, THIS, is a 2nd time of ripping the job (since you have already closed out of the previous time you had printed these films.
Everything else can be the same, but you made some changes to only one of the colors....and you find out that the new color change does not line up with the previous separations. Why?
It’s because each time you open a file and send to the RIP, it’s a single, unique instance in the ripping process. Oddly enough, this is not exact each time an entire file is sent and ripped. Each is slightly different. I can’t tell you why, other than it’s a math thing. It has to do with the entire document, reading and converting (vector) images into Raster. It’s looking over the entire file, and calculating and plotting where each cel area of a grid will be turned on or off for a solid color of ink to be placed. (that there, has to also do with printer resolution) but that is another topic.
When all of this calculation is complete, the file is ripped in your specific RIP. I’m using AccuRip here at our shop. It’s a low end RIP but it does it’s job. Still, there are some issues with low end rips. THIS miss registration (is the result of a 2nd send) and is one of those issues that can come from low end rips.
During the change from the first time you opened the file and printed, NEW DATA had been added to the file, thereby undergoing a whole new algorithm configuration (plotting and turning on or off) of the grid cels. As a result, your art and registration marks will not be in the exact same location as the previous send of the other colors.
How do we resolve this issue? Sadly, the answer is, you must reclaim the previous screens, (re-send all new films) together in one event - again. Otherwise, your screens will not line up and production will continue to fight with it and cause extended production time before they even begin to run the order.
You might think that having a higher end RIP is the answer, but not always. Here is another issue with sending a file with color separations when sending the separations. I’ve seen this happen in the CTS/DTS world for file sending. Here we go!
As we all know, there are many ways, methods, processes to print color separations. For those who separate a multi color file with an under base white, and will send the base white as a separate file, introduce the opportunity for miss registration. It’s actually not so much as “miss registration”as it is “distortion" from the other file that you are trying to match. A miss registration implies that the separation “could be”moved into position. In these descriptions, we are talking about distortion from one send to another send. This math issue - as described above, can play a role in file distortion of the same job file (because of) sending as two separate files. Each is read individually, treated differently, and therefore, can introduce a lack of exact alignment. How do we fix this?
To resolve this as being an issue, we send all colors (together) in one send. Some people have found it difficult to learn how to send colors together in one file. If it’s not set up properly, the colors sitting over the base will knock out anything that is underneath of it. There are ways to prepare your file so that it does not do this. In my opinion, this method is THE way to prepare a file for color separations in vector. That will have to be another topic.
Lastly, there can be other reason for miss alignment and/or distortion from separation to separation, but those typically have to do with older, more archaic printers and film material that are not as widely used today such as velum and older printers that heat up more than usual due to prolonged operation. The heat from these printers will soften the film positive material and cause it to stretch or elongate. A similar result comes into play with the older velum. Some people still have great results from these If you can learn to work with those as needed.
Thanks
Dot-Tone-Dan
