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Important!! Crop & Trim Marks - What, When & How
09-22-2012, 03:23 PM (This post was last modified: 10-10-2012 01:31 PM by Base_Camp.)
Post: #1
Solved: 4 Years, 8 Months, 4 Weeks, 2 Days, 13 Hours, 3 Minutes, 47 Seconds ago Information Crop & Trim Marks - What, When & How
What we're not referring to here is circles in a wheat field made by passing Martians, we refer instead to the eclectic collection of symbols one often observes on printed items before they're trimmed to size. We see more versions of this little device than I can recall, mostly they cause problems when making negatives but usually because of the different ideas folks have about how to make them and how they like to work.

  1. What Are Crop Marks?
    If you use Adobe software you'll often see them referred to as 'printer's marks' in the document setup dialogs. That's the point, they're mainly a device for the printer to monitor and control colour in the print process (lithographic or four colour process) including the depth of black. These are seen in the bars of colour and black each side and the bottom of the image below.

    Additionally the marks include positioning marks known as 'registration marks' seen as cross hairs in the corners of our image. These marks allow the printer to ensure with each press run the colours are being accurately overlaid so you don't get that awful ghosting in images which you sometimes see in poor colour printing or your newspaper.

    Finally (and more importantly for us) are the trim marks - sets of two right angle dashes in the four corners of our image - which allow the printer to cut stacks of the finished job accurately, trimming away anything not desired on the finished print but which was useful whilst going through the print process, including the printer's marks. This also includes 'bleeds' an area of the artwork which extends beyond the margins by design, often used with large solid areas of colour or pictures and photo's.

    [Image: crops_diag.jpg]

    In image 2 you see a red box fills the width of our page. If we simply sat a red box on our page and printed it then tried to trim the job any pages that were even 0.05 mm out of line would have white space at the side of the box. To combat this we use bleeds which ensure there's always a clean edge from our cut without 'unprinted' space showing where it shouldn't.

    But trim marks also allow the designer to configure accurately the way their layout will work on the page so they get the desired results when the job returns from the printshop. They help the designer foresee problems with their design and make improvements before a costly press run, or see how the space works on the finished product. In all good design and print work 'white space is just as important as filled space' a subject not in the scope of this article. A very good read though is "White Space Is Not Your Enemy" by Kim Golombisky & Rebecca Hagen, published by Focal Press ISBN 978-0-240-81281-6.

    [Image: bleed_diag.jpg]

  2. When Do I Need Them?
    Designing for Letterpress, standard design rules still apply, layout is important and therefore you will often benefit from the use of trim marks as a means of governing this principle. You may use a pattern on a piece of stationery which travels the width of your print area but do you want to risk the trimming process leaving the pattern slightly off centre by even a tiny amount which will show? It may be safer to bleed the pattern a little off the print area and trim away the waste. You can also use the trim marks to help you position press runs if you're using multiple colours in your design and you therefore need to align the plates so your colours appear in the right place and square on the page.

    There is a cost though. The crop or trim marks will set the size of your plate at the whole page size you're working with and if there's nothing in the bottom half of your plate except trim marks then you're paying for plate area that has no value, so use sparingly and only if you have to. You can still align your job on the paper when you print by printing a proof from your computer then measuring your ink position from the paper's edge against the corresponding distance on the proof.

    Even if you are printing two or more colours it is still possible to print all your colours on one plate and separate them for the press in a method we call 'dovetailing' which saves you wasting plate area you pay for and makes for very quick and easy 'plate swap' for your second colour run. This will be covered in another article.

    You may also find trim marks helpful for specifying how you would like your plates cut in which case just send directions with your file that the crops or trims are for separation purposes only and not to appear on the plate.

  3. How Do I Use Them?
    This will depend on your graphic design application software and there's a long list, Corel Draw, Quark, Gimp, Photoshop, Illustrator and Xara to name a few. We do favour Adobe software and Illustrator is the main program we use however, the common denominator between these programs now is often the 'pdf' (portable document format an Adobe file format designed by co-founder John Warnock back in '91) which allows designers to work in their favoured application but hand off files to media professionals in a more universal format. So you can design in Corel Draw and publish to .pdf which we can then work with in Illustrator to make film negative files.


    [Image: letterpress_layout_diag.jpg]


    If you need to use crops or trim marks then, it will depend on your application and we can't cover them all. We prefer clients to use the onboard features in their design package as these generally have consistent features that avoid some of the problems that occur with 'DIY' trim marks. However we ask clients NOT to use the crop marks in Illustrator found in the application menu under Effect -> Crop Marks (CS5). These are difficult to work with and can't be edited easily, please do NOT use Japanese crops either. We prefer Illustrator's trim marks found in the menu under Object -> Create Trim Marks (CS5) which by default have a 0.3pt line which is the minimum we can carry in an isolated line on a plate. If you work in InDesign then you can use the preferences dialog to specify the size and thickness of your crops, we suggest 3 mm long and 0.35pt - 0.5pt line thickness as per your preference. If you use the Illustrator trim marks we will shorten these for you, (nothing for you to do - we'll take care of it) to 3 mm this makes sure you're not paying for added plate area. To crop your artwork select all then on the menu Object -> Create Trim Marks. If this doesn't give you the page area you want put an empty white box the size of your page in the background of your artwork and centre to your page. Then click the box and form the menu choose Object -> Create Trim Marks, once you have your trim marks just delete the box.


This article for brevity sake is limited in it's parameters but feel free to contact us or post in the forum if you need help or have particular requirements.

LBP - The Team
http://lymebaypress.com
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10-25-2013, 02:18 PM
Post: #2
Solved: 4 Years, 8 Months, 4 Weeks, 2 Days, 13 Hours, 3 Minutes, 47 Seconds ago RE: Crop & Trim Marks - What, When & How
I would very much like to add just a brief footnote to LBP explanation on trim marks, if it hasn't been added elsewhere. When supplying artwork for plates many of our clients utilise trim marks from the object dropdown. Normally this will create trim marks using a Registration black, (100%,100%, 100%, 100%) and not a CMYK black, (0, 0, 0,100%). It is important that the artwork files supplied for plates have the correct CMYK black.
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