Hot Foil Stamping

[Tech]

I'm trying to understanding the process of hot foil stamping and how plates or heat is controlled to align multiple layers of foil stamping. We often prepare art files for this type of printing on covers but also consistently see test results that looks poorly where art work that should be align and not touch doing exactly just that. Usually to my untrained eyes, foil are easily spreading at least 2pts all around the die/plate area. Is the heat causing this problem or the plate pressure or both? What can we do on our end to construct our files better so we can help vendor prevent what seems like foil spreading issue?

Thanks in advance.

 

[prepression]

Better to discuss this issue with whoever is doing your stamping. Sounds like a problem with their machinery.
Amazon.com: Exploring Digital PrePress: The Art and Technology of Preparing Electronic Files for Printing (Design Exploration Series) (9781418012366): Reid Anderson: Books

 

[beermonster]

our foilers only want vectors - so only supply vectors

some kind of registration - sounds simple but you'd be amazed...

give them something to position and register to, and discuss and agree acceptable tolerances up front.

 

[jlee]

Heat definitely causes the spreading you are seeing. Our hot foil dies are compensated to account for this. Also, mentioning the pressure that would have an effect. registration is quite difficult to achieve and a lot of factors into how you're foil plates are manufactured and mounted can have significant effect.

 

[Tech]

We are working with a different vendor today and i'm instructed by some editorial staff to follow vendors exact spec and build-in a 3/64 gap between two foils in anticipation to compensate for foil spread. The logic is there but what happens if they manage to apply proper heat and pressure and foil doesn't spread out enough to meet and fill that gap? Why have such knee-jerk method as solution?

3/64 may not sound much but when you have very detail and thin artworks butting together that 3/64 is like the size of grand canyon. I rather have foils spread and overlap by each other knowing we don't have gaps showing through. Can anyone confirm that this is a common practice among vendors and I'm just light-years behind on proper file setup for hot foil stamp jobs?

 

[Gregg]

our foilers only want vectors - so only supply vectors.

Our vendors always prefer vector, but sometimes it is just not possible. In those cases we supply 1200dpi bitmap files (granted the artwork originally began as a 300dpi CMYK file), so the bitmap file is interpolated, but the end result is always pleasing.

 

[kerstenp]

Are you talking about a die that has expanded that is bigger than the original art, I.e. a 6" line now measures 6.032 inches? If that is the case, you need to order your foil dies with heat compensation. This is where the dies are made slightly smaller to allow heat expansion.
If you are talking about excess foil flaking off around the image, then the foil could be too hot or the wrong type of foil is being used for the job/paper stock.