In-line Flexo Printing Guidelines
Introduction for the bag buyer and packaging sales person
In our experience, most custom printed bag projects get started with people not trained to get the art ready - the person needing the bag and the packaging salesperson. It is important to have a basic understanding of what is needed to get a custom printed project off to a good start. Indications of plate costs and lead times we provide are based on receiving correctly prepared B&W or digital art work.
The following are not “correctly prepared art”:
• Business cards, letterheads, photocopies, faxes, etc.
• B&W or scanned art requiring more than 50% enlargement.
• Previously printed paper bags or other packages.
• Overall designs not positioned on one of our bag templates.
• Films and/or plates not to our specifications.
• Multi-color designs with tight register and trapping requirements not prepared to in-line flexo specifications.
• Designs with halftones (photos) and/or flat screens requiring adjustment for in-line flexographic printing.
• Images saved as Illustrator files
This is not to say it is impossible to complete a project with these materials - only that it may cost more and take more time.
Supplied artwork formats that work best
• Adobe Illustrator or high resolution PDF (600dpi or higher) files preferred.
• Original vector art with fonts outlined and high quality images embedded.
• CD for Mac or CD/DVD for PC.
• As email attachments to email@example.com or firstname.lastname@example.org. Typical maximum email attachment is 7 to 10 megabytes. We use Stuffit compression utility. Files can be uploaded to our online dropbox, at https://www.hightail.com/u/TULSACK-art
• With digital art please send all fonts and image source files and confirming PDF or hard copy indicating correct output.
• All supplied production materials subject to review for quality and suitability in our process. Supplied plates and/or dies must be accompanied by film negatives.
Introduction for the graphic artist
Most artists and designers have a background in offset lithography, not flexography. If there is some flexo experience, it is in narrow web for labels, not the wide web used for paper packaging. These Art Guidelines are intended as a basic “how to” for designers and artists working on new flexographically printed shopping bag projects. The Guidelines should help to get the art done correctly the first time, minimizing prep expenses and prep time. If anything is unclear please ask.
In-line flexographic printing & bag making
Flexography is a relief printing process using photopolymer plates that are .112 thick. In many respects flexo is like printing with rubber stamps. Our printing is done in-line with the bag making. Rolls of paper are unwound into the bag machine, printed up to three colors, handles applied, side folds formed and seam glued, individual bag cut away from web of paper, bottom folded and pasted, and the finished bag is packaged for shipment. Click here to view pictures of this process.
Ink color matching and proofing
• We use Pantone colors specified, or can custom match submitted materials. Please specify colors from the solid uncoated Pantone book, with the exception of colors listed on pages 1.3-1.5.
• There is no charge for color matching. GCMI colors may be used.
• PMS ink color standards and formulations are per our ink supplier’s current PMS swatch book. Please specify the PMSU shade that best matches color(s) previously printed on coated paper. May be a different PMS #. There are PMSC colors that can not be matched on uncoated papers.
• Ink drawdowns for PMS colors on TULSAKRAFT™ VERSA (white side) and White Kraft sent only when requested on P.O., or when there are traps or overprints that should be approved prior to production. We send ink drawdowns for all PMS matches on Natural Kraft and TULSAKRAFT™ VERSA (natural side), as well as for custom matches to colors other than PMS. Approval is needed before bags can be produced.
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Design templates, logo positioning and bag proofing
Unless the design is no more than a spot print, the designer should have a template before starting artwork. Each bag size has its own template. Click here for templates. Orders for spot imprints not on a template must include logo size and positioning instructions on the P.O., e.g., “Enlarge to 6” wide, position center left to right, 3” up from bottom.” An art fee will be applied when art is not sent on templates.
All bags are proofed, usually as a hand-folded color bag printed with an inkjet printer on the actual paper type. The hand-folded bag is to be viewed for logo size & positioning only. Colors on the proof are an approximation, the ink drawdowns will show the true ink colors used on press. The proofs do not show actual screens. When there are screens, a conventional dylux blueline will be burned from a negative for approval of the screens. Alternative proofs may be furnished when tight register and/or complicated trapping of multiple colors are involved. Bag proof approval is needed before production.
Line width and type size
• Minimum positive printing line width: Two (2) point
• Minimum reverse printing line width: Three (3) point
• Minimum positive printing type size: smallest letter should measure .10" in height
• Minimum reverse printing type size: smallest letter should measure .12" in height
These guidelines are subject to review with serif type faces, and with designs including areas of broad solid coverage along with small type in the same color. In these situations type/line may need to be larger and/or bolder. Think big for visual merchandising. Promote the brand to everyone who sees the bag, not just the person holding it. Bags are Walking Billboards.
Register tolerance and trap
Wherever two colors meet, a minimum 4.5 point - 1/16” - is required to trap the colors. Where two colors are adjacent and not to touch, there should be a minimum 4.5 points of space between them. As a general rule this register tolerance precludes the use of two overprinting colors to create a third color, whether with solids or screens. If attempted this would need a third color such as black to outline the shape.
Screens and halftones
• The line screen used in our process ranges between 45 and 55. The coarse screen is not apparent from typical viewing distance and insures cleanest possible dot reproduction. Due to the differences between how wide web flexo and offset litho reproduce screens and halftones, we request the opportunity to review the design elements to provide specific production art direction as early in the planning process as possible.
• Halftones must have strong contrast, as must steps between manually selected screen values of the same color. Subtle tone variations will not reproduce. Please have the artist contact us before going very far with a design using halftones and screens. We're happy to supply printed bag samples with halftones upon request.
Post Print & Hot Stamp Guidelines
Post printing and hot stamping are executed on bags after they are manufactured. There are limitations to these processes, including:
• Logos combining heavy coverage and reversed images may not print well. Positive images are preferred.
• Screens, borders and heavy coverage areas will likely distort when post printed over the folds of a bag. Click here for templates, fail safe tools to size art correctly and avoid distorting areas of the bag.
• No metallic inks.
• Logos containing fine detail and small reverses will probably fill in when hot stamped. Enlarge these areas or consider post printing for a better result.
• Click here for typical art reproduced successfully in post printing and hot stamping.
• P.O. must specify logo size and positioning instructions, e.g., “Enlarge to 6” wide, position center left to right, 3” up from bottom.”
• Logos must be positioned at least 1” below the handle/patch.
• Specifications to center top to bottom may be adjusted to “center best” when true center will cause image quality problems due to folds, patches, handles, etc.
• Screening limited to 30% density at 30 line screen.
• We strive to produce the highest quality in our printing and hot stamping. Changes will be suggested when necessary to achieve a quality job within the capabilities of our processes and the materials available.
• Click here for copy size guide. Substrate and design combinations may reduce size capability.