How does a print provider manage transparent areas within a PDF file?

Question

Case 1: Suppose I have simply a text to print on a plastic transparent sheet unlike paper. Just like the example shown below. If you see text is printed on a plastic sheet and then sheet is pasted on bottle.

Now, I created my document in Illustrator with no BG, but PDF shows white even when it's not there. It's not there actually if we open PDF again. But how would printer manage transparent BG print? Can it be done with PDF or I need to send a PNG image instead and tell him dimensions of print vocally?

Case 2: If I don't want even plastic sheet, just letters to be printed of a cursive text (letters attached together so I can paste it on bottle or wall with glue), be it made of any material, can this be done with PDF too? Or some other way? And how does printer manage this? (To understand more what I want to ask, see the word hello. Imagine it's made of any material, paper, plastic etc., I give the printer guy a file for the same without background.

How would printer print this hello, unlike other stuff which have backgrounds/rectangles/circles?

Basic doubt in both cases is related to transparency after print and a document recommendation for the same if it's not possible with PDF just like normal prints.

Answer 1

If you print a PDF to your home inkjet printer.. does it print white ink to make the paper white? No.

What is white does not print. White = transparent on press.

It doesn't matter what substrate you are printing on (plastic, metal, paper). It doesn't matter if there's a die cut or not. In most printing white is seen as transparent.

The only way white ever prints is if a white ink is specifically asked for. And even in those cases the artwork is rarely set up using white as a color because cameras/platemakers don't see white.

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As for things like those large letters.. there's no artwork there.. It's all merely a die cut. Which is similar to a "cookie cutter" if you will. The entire shape is created by "stamping" a cut in a rectangle, leaving the remaining graphic shape. There may not be any actual printing taking place for such decals, merely custom dies made.

Answer 2

You never send a PNG for printing. Forget that.

Yes, transparent background shows up as white artboards in Illustrator/InDesign, but it is still transparent background.

No, transparent background will never print as a solid white background.

Send a PDF to print.

Answer 3

White does not generally print. If you want to print white then you need to be very careful about communicating with your printer. Even if the file has a white channel they might omit it.

The letters on the wall are most likely laser cut, or surface cut. Mainly due to their size. I mean they can be die cut, but since making the die costs money and a big die needs a big machine and lots of time for die preparation. Laser cutting and surface cutting with a blade and creasing with die roller is pretty cheap these days. Since the file is prepared the same way there's no difference.

What you do is you buy acrylic or polypropylene/polyethylene, and stick it in the laser cutter. This is ok for runs that aren't in the thousands or tens of thousands for small pieces. Certainly if you only need 1-100 it is the way to go.

Why acrylic? Well you can get it in nearly any color imaginable and it laser cuts beautifully. Also it is a traditional signmaking/advertisement material. The picture below does not do the color justice as they over exceed the gamut of your monitor by a safe margin. You have to see the material samples as they can have surface and internal texture to them, tranparency and translucency.

Image 1: One of my limited (not full set) color sampler. Note the fluorescent colors look really dull in the picture, they hurt your eyes in reality.

Note that there is a lot more you can do with a laser than diecut, you can engrave, mark and even 3d contour the surface. Also the polyethylene sheets can be printed in most normal printers and then laser cut. Likewise the acrylic can be printed on with UV printers and sublimation processes.

Answer 4

As everyone else has already stated - white = transparent in pretty much all print applications, unless you are explicitly asking for something in white to be printed (ie. white text on a transparent label/sticker).

Regarding your question using the "Hello" as an example, that would likely involve the use of a custom die, which can run your costs up fairly substantially. In a project where I needed a 4" x 7" soapbox shape with a hole near the top (it was a door hanger), the custom die to produce this ran me $700CAD.

What this does is, instead of the printers just cropping your print run into your standard square/rectangle/whatever, a die is used to cut the shape custom.

Imagine graphic stickers, and how they're usually cut around the shape of the artwork, rather than the artwork being on a big white background. This is more of a print press/company capability, but if you really want it, you can typically do your own hand-cutting with an exacto knife and a bit of time, if it isn't scaled too small.

Answer 5

All above asnwer are good. I will just like to illustrate to help other better realise what is the real conent of the file that translated to "print this".

Here we have file in CMYK with objects.

As you can see the panel show ALL colors that are used for CMYK AND every additional SPOT ones that you might added. Those colors are translated to plates (or any other printing medium depending on chosen method). So only Cyan, Magenta, Yellow and Black are "Visible" and used. Anything else you see (like the white background) is "visualisation helper" just like the checkered one used to show transparency. Some programs go even further and in "separation/print preview" allow to simulate color of the medium you would print on (because magenta look totally different when printed on green paper).

Now the Magenta outline around the Lorem Ipsum is what printer would see if you wanted to have a styro letters (like in the second photo you show). What color you would use inside have no role as only the outline is translated to the path of cutting (of course after some cleanup, joining and making it more efficent).

THE MOST IMPORTANT THING It's your role, as a designer, know that what you see is not what you get. A white background in program is not something that is printed. Guide lines, text boxes are not things that are printed (unleast you want it to be).
There are additional rules for specific type of print or purpose.
If you look on your bottle you will see a barcode on WHITE background. This mean that on design stage you need to be aware of this. You need to know you don't print with only black (text) but you also need to arrange (with printhouse) the print of SPOT color. That need to be printed before black (for various reasons). Then you need to remember that you need to place that spot color. You cannot assume "oh everything in the BCKGRNG shows white so I just place barcode and make square around it".