What Does "Registration Shift" Mean?
Almost every print method is subject to slight registration shift during the printing and cutting process. "Registration" refers to the alignment of ink plates for transfer onto the substrate, the correlation of multiple colors to create a single image and the positioning of the blade or die to cut a precise line along the edge of the sticker. All of this occurs in motion, hence the likelihood of some shift.
Some print methods, such as flexography, have registration allowances up to 1/64” because the flexible plate technology used for this method will inevitably slip a little bit during production. 1/64” is still pretty minuscule and shouldn’t be discernible to the eye, however it can be noticeable when there are small strokes of different ink colors around text or drop shadow effects. This can result in blurry lines or a weird “ghosting” appearance around text, therefore we often advise removing such features if we are printing your labels on a flexographic press.
Borders can also be an issue with flexo printing. The image below illustrates how this slight shift can affect the borders that are printed over the edge of a label. For this reason, we often recommend either removing borders from the very edge of the label design or insetting the border at least 1/8″ from the label’s edge.
The human eye is so perceptive that even a fractional shift will be visible making the border look out of alignment – thicker on one side than the other. This is especially true with thin borders and less so with very thick borders. If you have an outside border in your artwork, we generally make our recommendations about revising your artwork ahead of time.
In digital printing, registration tolerance is about 1/100”, which is extremely accurate thereby making visible shift pretty much a non-issue. However, shift can certainly occur, particularly when there is complicated custom shape that the plotter has to cut around. Part of the beauty of digital printing is that it enables unique contours without the need for dies, but the more curves and peaks a blade needs to trace around, the more probable a little misalignment will occur. This will be more noticeable in the case of borders once again. But in most situations, digital printing registration is very precise. Digital printers make registration marks outside the sticker cutlines for the plotter to read to ensure great accuracy while printing and cutting, so if shift is very apparent, it likely means there was an issue with printing, like a foot was loose or the feeder slipped.