The Platen Gap

In today’s post, ImagePrint Today tackles the subject of the platen gap.  Though often ignored or misunderstood, this setting can be a key factor in achieving sharp, problem free prints.

So.. just what is the platen gap, anyway?

The platen gap is simply the distance between the print head and the surface of the paper as it passes through the printer.  As papers of different thicknesses are loaded, this distance will necessarily become either larger (with thinner papers) or smaller (with thicker papers).

These differences in distance can affect the quality of the print.   Narrow gaps caused by thick papers can cause the print head to scuff the surface of the media, not only damaging it but potentially damaging the print head as well. Wide gaps caused by thinner papers can result in print banding, or may cause the output to look too soft due to inaccurate dot placement.

So, in order to keep the gap consistent it’s important to adjust it to compensate for different paper types.

Bridging the gap

Methods for setting the printer gap can vary from printer to printer, but there will typically be a method available either through software or via  the printer’s front control panel, or both.

From the Front Panel

For most Epson professional series printers, if your printer has a front control panel you can set the platen gap to Standard, Narrow, Wide, Wider, and Widest.  (As a guide here’s the paper weights (gsm) each setting corresponds to:  Narrow = 150 gsm, Standard = 190 gsm, Wide = 260 gsm, Wider = 320 gsm and Widest = 500 gsm.)

Standard is the default platen gap setting, and it’s a special case as it can be overridden by software—if set to Standard the printer will automatically change the gap based on the Media Type chosen in the printer driver or RIP.  Because of this characteristic Standard is the preferred platen gap setting in most cases (more on that later).

Custom Papers – In addition to the standard platen gap settings, Epson also offers a Custom Paper configuration option from the printer’s front panel.  This allows you to setup user defined settings specific to the media you use, and can help you fine tune your platen gap if you are unable to get a good result with the default offerings of the printer or printing software.  As part of the Custom Paper setup process a paper thickness pattern is printed containing a series of printed lines.  You then pick the line that is most vertically straight and enter that into the printer’s front panel—the printer uses that information to determine the best platen gap for the loaded media.  At the end of the Custom Paper creation process you give your new settings a unique name and will be able to recall it via the front panel for future use.  When a Custom Paper is active, it will NOT be overridden by any paper settings sent via software.

From Software

As mentioned earlier, for Epson printers your printing software (whether the standard driver or an advanced driver like the ImagePrint RIP) will set the platen gap programmatically when the printer’s front panel is set to Standard (or if the printer has no front panel) and the Media Type setting in the software is set to one of the Epson papers.  (The Media Type is chosen via a drop-down menu—in ImagePrint you’ll find it in the Print Dialog’s OPTIONS window).

Each Media Type setting contains parameters that will be sent to the printer with information on how best to handle that paper.  But…since that list is supplied by Epson, only Media Types for Epson papers are provided.  So, when using a third party media you must choose an Epson paper closest to the thickness of the paper you are using.

Because you are limited to Epson papers in the media list, choosing the correct media type for your desired platen gap can sometimes be a matter of trial and error often prone to mixed results, especially when using third party papers that do not have specific media type settings associated with them.

This is even more true when using the standard Epson driver with 3^rd party papers.  Why?  Because with the standard driver, not just the platen gap is set via the Media Type setting–the inking characteristics of the paper are also determined by that selection.  That can be a huge headache if you want to avoid banding and other issues caused by over or under inking on non-Epson papers.

With ImagePrint we specifically store the inking information (we call them recipes) inside the actual ICC paper profiles so that a mismatch can never occur.  Changing the media selection in ImagePrint will have no effect on how much ink is put down on the paper—it only affects the platen gap and other paper feed related settings.

So there you have it—hopefully we have helped to fill any “gaps” in your understanding of the platen gap!