Uncoated stocks have a porous surface, which absorbs ink and can make colors appear more dull and not as crisp.
If you think about it in simple terms, coated stocks are like a pane of smooth glass and uncoated stocks are like a sponge. Ink will sit nicely on top of a coated (glass) stock surface, giving a bright and colorful, clean crisp output. In contrast, uncoated stocks will absorb some ink (like a sponge) causing colors to appear more dull and less vibrant; even not as sharp.
Print settings are optimized and calibrated for each type of stock to give the best output; however, this effect is a property of the paper. Many designers will add more saturation to colors when designing for an uncoated stock due to this effect. Others will create their designs with this "inconsistent" look as a desired effect, as it does tend to make the print feel more rustic, or handmade.
Due to unavoidable shifts that occur during the production process, it is important to place any important content of your design (text and graphics) at least 0.125” away from the edge (trim line). Content within our recommended safety margin of 0125” will not be trimmed.
The safety margin can be defined in Adobe InDesign during the document setup process or in the Margins and Columns section under Layout. In Illustrator and Photoshop, you will have to set up these guides in the document.
Setting up proper safety margins will help avoid having your objects look as if they are about to fall off the page and ensure they are not trimmed off.
Bleed is the artwork that extends past the trim line or finished size of your product. If any element of your artwork is designed to be printed to the edge, it must be extended past the trim line and into the bleed area by a minimum of 0.125".
The addition of bleed compensates for uncontrollable shifts that occur during the printing and trimming process; and ensures that any content touching the edges does not leave unwanted gaps or borders.