Printer has me confused about document setup

[Crista Anderson]

Hi.

I started working with a professional printer and his setup requirements have me confused. I am a newb btw. 

I created an 11x17 doc with an 1/8 bleed all around. He printed it on 11x17 paper and it came out weird. So he told me to make the document's canvas size 12x18 instead, and to add a 1/8 bleed around the 11x17 doc, and that he would print it on a 12x18 piece of paper to be true to size. 

My question is, why do I need to add the canvas size to my 11x17 document? Why can't I just create an 11x17 doc, add the bleed and he print the sucker on 12x18 paper? I truely don't understand why my file needs to be 12x18 when that gets cut off anyway.

Please help. 

[Conrad C · Accepted solution]

I created an 11x17 doc with an 1/8 bleed all around. He printed it on 11x17 paper and it came out weird.

By @Crista Anderson

How did it come out weird? What we know is that those specs are guaranteed to fail. If you have 11 × 17 with a 1/8 bleed on 11 × 17 paper, there is not enough space to print the bleed because the total area including bleed has to be at least 11.25 by 17.25, which obviously can’t work because it’s larger than the paper.

That is why the printer next said to create a 12 × 18 document. That provides enough room to print the image (11 inches wide) plus the 1/8" bleeds on both sides (2 * 0.125, or 0.25). The resulting 11.25 inch wide document will fit within a sheet of paper 12 inches wide.

If you are unsure about what bleeds are for and how they work, I found this document from a quick web search, and it explains it well:

Photoshop How-To: Adding Bleeds and Crop Marks

The printer may have told you that your document needs a bleed if they noticed you have artwork that goes all the way to the edge of the canvas. The document would not need a bleed if the design had no elements near the edge of the canvas.

[Crista Anderson]

Thank you for answering.

I read the article you sent, and I think what he described to me is called adding "trim marks." It was just communicated poorly. I was very confused.  I think the doc came out weird because those guides were absent from the canvas. I have a multi-page project with odd fold lines. Again, the article you sent was very helpful. I'll use it as a reference going forward. Thanks.