Flexographic (Flexo) Printing

What is flexographic printing?

Flexographic printing (flexo) uses flexible relief plates made of rubber or photopolymer, mounted on cylinders. Fast-drying, usually water-based inks are transferred from an anilox roller to the raised areas of the plate and then onto the board. Flexo is the most common method for printing directly on corrugated shipping boxes, and it is also widely used for labels and flexible packaging.

Strengths

• Low unit cost at volume
• Fast production on large runs
• Prints directly on corrugated, even rough kraft liners
• Water-based inks keep boxes recyclable
• Bold, durable graphics for logos and handling marks

Limitations

• Plates per color add setup cost
• Less fine detail than offset or digital, especially on fluted board
• Best with 1–3 spot colors; full-color process flexo is possible but less common for small runs

How flexographic printing works

Flexography (flexo) uses flexible relief plates made of photopolymer, mounted on cylinders. The raised image areas pick up ink from an anilox roller, a precisely engraved cylinder that meters a consistent film of ink, and transfer it to the substrate. Each color has its own plate and print station.

Flexo is used across packaging: corrugated boxes, paper bags, labels, flexible films and tape. For corrugated, there are two main approaches:

• Post-print: finished corrugated sheets are printed directly, often on a flexo folder-gluer that prints, slots, folds and glues regular slotted containers in one pass.
• Pre-print: the liner is printed on a roll before it is made into corrugated board, giving higher quality on very long runs.

Water-based inks are standard for corrugated flexo, which dry quickly into the absorbent liner and keep boxes easy to recycle.

Why flexo dominates shipping boxes

• Speed: flexo folder-gluers convert and print boxes at high speed.
• Low cost per unit at volume.
• Durable inks that withstand shipping.
• Ideal for simple, bold graphics: logos, handling marks, text.
• Integrated converting: printing, slotting and gluing in one machine for RSCs.

Most brown shipping boxes with a one- or two-color logo are printed by flexo.

Designing for flexo on corrugated

Corrugated board is not perfectly flat: the flutes create subtle ridges, and the liner absorbs ink. Design with that in mind:

On kraft board, dark colors look best; on white-top liners, colors are brighter.

Plates and setup costs

Each color needs a photopolymer plate sized to the print area. Plates are a one-time cost per design and can be stored and reused for reorders as long as artwork does not change. Plate costs are moderate, which is why flexo is most economical at roughly 1,000 boxes and above, and very economical at tens of thousands.

Flexo vs. digital on corrugated

Many brands start with digital for small runs and switch to flexo for their highest-volume shipping boxes once designs are settled.

Flexo beyond boxes

Flexo also prints many packaging accessories: custom packing tape, paper bags, poly mailers, labels and flexible films for stand-up pouches. On films, modern high-definition flexo achieves detailed full-color graphics.

Sustainability

Water-based flexo inks on corrugated are compatible with standard recycling. Flexo printing on kraft with one color is one of the lowest-impact ways to brand a shipping box: minimal ink, no lamination and easily recyclable.

When to choose flexo

• Shipping boxes and mailers in quantities of 1,000+ with simple graphics
• One- to three-color logos and text
• Reorders of a stable design
• Cost-sensitive, high-volume programs

Choose digital for full-color short runs and offset or litho-lamination for photographic premium graphics.

A short history of flexography

Flexography grew out of "aniline printing" in the early twentieth century, when rubber plates and fast-drying dyes were used to print paper bags and wrappers. The name "flexography" was adopted in the 1950s to give the process a fresh identity as inks and plates improved. The real transformation came with photopolymer plates, laser-engraved ceramic anilox rollers and digital plate-making, which brought dramatic gains in detail and consistency. Today flexo prints a huge share of the world's packaging, from corrugated shipping boxes to labels and snack bags, and high-definition flexo can reproduce fine graphics that once required offset or gravure.

The anilox roller: why flexo is consistent

The anilox roller is the unsung hero of flexo. Its surface is engraved with millions of tiny cells, each holding a precise volume of ink. A doctor blade scrapes away excess ink so only the cells remain filled. The plate then picks up exactly the ink it needs.

• Higher cell volume carries more ink for strong solids on absorbent kraft.
• Finer cell counts carry less ink for detailed images and halftones.
• Printers choose anilox rollers to suit the substrate and design, which is part of the press setup for your job.

For brands, the takeaway is that flexo color is controlled mechanically and repeats well across long runs and reorders.

Inks for flexo packaging

On corrugated, water-based inks absorb into the liner and dry fast, which is why flexo-printed shipping boxes come off the line ready to bundle.

Pantone matching in flexo

Flexo usually prints with mixed spot inks rather than CMYK, so your brand color can be mixed to a Pantone reference. The final appearance depends on the substrate:

• On white-top liner, colors look close to the Pantone guide (use coated or uncoated references as advised).
• On kraft liner, colors look darker and warmer; a Pantone color mixed for white board will not look the same on kraft.
• Drawdowns (ink samples on the actual board) are the best way to approve color for flexo jobs.

Quality checks in flexo production

Printers check flexo work for:

• Registration between colors
• Solid density and color against the approved standard
• Fill-in or dot gain in fine text and halftones
• Washboarding (ridged appearance) on fluted board
• Barcode readability with a verifier
• Ink rub resistance so print survives shipping

Common mistakes with flexo artwork

1. Fine serif text and hairlines that fill in or break.
2. Photos and soft gradients that band or posterize on corrugated.
3. Tight registration between colors (thin outlines around shapes).
4. Expecting white-board colors on kraft.
5. Barcodes too small or printed across flutes without checking scan grade.
6. Full-bleed solids on B/C flute, which can look uneven.

Worked example: a wholesale shipping carton

A food brand ships cases of 12 jars to retailers in a 16 × 12 × 10 in RSC, 5,000 boxes per order.

1. Board: C-flute 32 ECT kraft.
2. Print: two-color flexo: brand logo in dark green, product name and case count in black, plus handling icons.
3. Barcode: case-level barcode (for example ITF-14) printed large with quiet zones.
4. Result: a durable, recognizable case at a very low cost per box, easy to recycle.

Flexo plates and dots

Flexo plates are made from photopolymer, a light-sensitive material that hardens where it is exposed. The raised areas of the plate carry ink; the recessed areas do not. Modern digital platemaking images plates with a laser, which gives sharper detail and more consistent results than older film-based methods. Flat-top dot technologies help plates hold small highlight dots and print smoother tones, which has steadily improved how photographs and gradients reproduce in flexo.

Plates are flexible, which lets them wrap around a cylinder and print on uneven surfaces like corrugated board. That flexibility is also why fine detail is harder: the plate compresses slightly under pressure, and dots grow. Designers working with flexo allow for this "dot gain" by avoiding very small highlight dots, using minimum line weights and keeping type above a minimum size.

Pre-print and post-print corrugated

There are two main ways to print corrugated with flexo.

Post-print means printing directly onto finished corrugated board. It is the most common method for shipping boxes. Because the press prints onto the ridged surface of the flutes, very fine detail is limited, and heavy solids can show slight "washboarding", a faint striped pattern where the flutes sit under the liner.

Pre-print means printing the liner paper on a roll before it is made into corrugated board. Printing on smooth, flat paper allows much finer detail and process color, often close to offset quality. Pre-print is used for high-volume retail-ready packaging and displays, but it requires large quantities because the printed liner must be run through a corrugator.

For short and medium runs where high graphic quality is needed on corrugated, litho-lamination (an offset-printed sheet laminated to corrugated) and digital printing are the usual alternatives.

Spot colors, process color and simple graphics

Most flexo printing on shipping boxes uses one to four spot colors. Each color is a separate ink mixed to a specific shade and needs its own plate. Spot colors give strong, consistent brand colors and keep setup simple. Process color (CMYK) flexo reproduces photographs and full-color artwork, especially on pre-print and on smoother boards, but post-print process color on corrugated has limits in detail and smoothness.

For many brands, a one or two-color design on a kraft or white box is the most cost-effective and recognizable approach. Bold logos, simple icons, patterns and clear typography all reproduce beautifully.

Registration and trapping

When several colors print one after another, each plate must line up precisely. Small variations in registration can leave thin gaps or overlaps where colors meet. Designers use trapping, a slight overlap of adjoining colors, to hide these variations. Flexo generally needs more generous trapping than offset. Your supplier's prepress team usually applies trapping, but designs that avoid very tight color fits, such as thin colored outlines around other colors, print more reliably.

Barcodes on flexo

Barcodes print well in flexo when a few rules are followed. Bars should run in the direction of print travel where possible, so any slight stretching makes bars longer rather than wider. Prepress applies a bar width reduction to compensate for ink spread. Print barcodes in a single dark color on a light background, never in a tint or several colors, and keep quiet zones clear. Ask for barcode verification on the first run if your products are scanned at retail or in warehouses.

Flexo on films, labels and pouches

Flexo is not only for corrugated. It is widely used for flexible packaging such as films, pouches and wrappers, for labels and for paper bags. On films, flexo prints with high speed and consistent color across long runs, often with white ink as a base layer under colors. Many flexible packaging lines print, laminate and slit in a series of steps, producing printed rolls that are later formed into pouches or wrappers. If your packaging system includes cartons, pouches and labels, aligning color references across all three helps the brand look consistent even though each is printed differently.

Water-based, UV and solvent inks

Flexo inks fall into three main families:

• Water-based inks are standard on corrugated and paper. They dry by absorption and evaporation and are well suited to recycling.
• UV-curable inks dry instantly under ultraviolet light, giving sharp detail and good rub resistance. They are common on labels and some cartons.
• Solvent-based inks are used mainly on non-absorbent films where fast drying and adhesion are needed, with emissions controlled at the printing plant.

For paper-based packaging, water-based inks are usually the right choice. They support recyclability and perform well on kraft and white liners.

Costs and reorders

Flexo has a fixed setup cost in plates and, for die-cut boxes, a cutting die. These are one-time costs for a given design and size. Once made, they can be stored and reused for reorders, so the second and third orders of the same box are cheaper than the first. If you change artwork, only the affected plates need to be remade. For brands with stable designs and regular reorders, flexo becomes very economical over time. Keep artwork changes to scheduled updates so you do not pay for new plates more often than necessary.

Proofing flexo jobs

Flexo proofs are usually digital PDFs showing artwork on the dieline with colors indicated. For color-critical work, ask for a printed draw-down of your ink on the actual board, which shows how the color looks on kraft or white liner. On the first production run, a press check or approved production sample becomes the reference for future reorders.

Flexo artwork checklist

• One to four spot colors where possible, with Pantone references.
• Minimum line weights and type sizes confirmed with your supplier.
• No fine gradients or very small highlight dots on post-print corrugated.
• Barcodes in a single dark color, oriented correctly, with quiet zones.
• Generous trapping between adjacent colors.
• Artwork placed on the correct dieline, allowing for flaps and folds.

Flexo for retail-ready and display packaging

Retail-ready packaging, cases designed to go straight onto shelves, and corrugated displays often combine flexo with other methods. High-volume retail-ready trays may be printed by pre-print flexo for strong graphics. Smaller runs of displays may use digital or litho-laminated printing. Flexo's strength is consistency across very large quantities, which suits national retail programs where the same case appears in many stores.

Choosing board color for flexo

Flexo prints on kraft and white liners. Kraft is economical and natural-looking, and dark inks such as black, navy and deep green print with strong contrast. Light colors and pastels look muted on kraft because the brown shows through. White liners give brighter colors and suit designs with lighter tones. Mottled white liners are a cost-effective middle ground. Choose the liner color with your design rather than after it, because the same artwork looks very different on each.

Flexo color consistency across runs

Flexo is highly consistent when ink color, anilox volume, plate and board stay the same. Changes in board, such as a different liner supplier or a recycled liner with a different shade, can shift appearance. Keep an approved reference sample and share it at every reorder. For brand-critical colors, ask your supplier to record ink formulas and press settings so they can repeat the result.

Flexo printing on the inside of boxes

Shipping boxes can also be printed inside with flexo, often in one color. A message or pattern inside a plain kraft shipper adds a surprise at modest cost. Interior flexo printing is usually planned with the outside print and requires the board to pass through the press for each side, or a press set up to print both sides.

When flexo is not the best choice

Flexo is excellent for long runs of simple graphics, but other methods may suit better when you need fewer than a few thousand boxes, when artwork changes frequently, when you have many versions in small quantities, when you want photographic detail on corrugated post-print, or when you need samples quickly. Digital printing and litho-lamination fill these gaps. A good supplier will recommend the right method for each project.

Flexo glossary

• Anilox roller: an engraved roller that meters a precise amount of ink to the plate.
• Plate: the flexible, raised image carrier made from photopolymer.
• Dot gain: the growth of printed dots compared with the file, managed in prepress.
• Trapping: a slight overlap of adjacent colors that hides registration variation.
• Post-print: printing directly on corrugated board.
• Pre-print: printing on liner rolls before corrugating.
• Washboarding: faint stripes caused by flutes under the printed liner.

Flexo printing and the shipping box journey

Printed shipping boxes face rough handling: conveyor belts, stacking, rain and scuffs. Flexo inks on corrugated are designed to withstand this, but design choices also help. Dark, heavy solids show scuffs more than patterns or lighter coverage. Bold logos and patterns hide minor marks and still look good after transit. If boxes will travel without an outer carton, consider a protective varnish or choose designs that tolerate wear.

Flexo for multi-SKU programs

Brands with many products in different shipping boxes can standardize designs to share plates. A common brand pattern or logo can be printed on several box sizes with the same plates if the artwork is placed consistently. Product-specific information can be added with labels rather than separate printing plates. This reduces setup costs and simplifies reorders while keeping the brand consistent.

Reading a flexo quote

A flexo quote typically includes plate costs (one-time per color and design), die costs for die-cut boxes, board, printing and conversion per unit, and freight. Some suppliers amortize plates into the unit price; others list them separately. When comparing quotes, check whether plates and dies are included, how many colors are quoted, which board grade and liner color are specified, and whether reorders reuse existing plates and dies. A clear specification makes comparison easier.

Environmental benefits of flexo on corrugated

Flexo with water-based inks on corrugated board is one of the most recycling-friendly printing combinations. Corrugated boxes are widely recycled in the United States, and water-based inks do not interfere with recycling. Simple one or two-color designs use relatively little ink. For brands focused on sustainability, a well-designed flexo-printed kraft box can be both practical and attractive.

Flexo printing timeline

A typical flexo job follows a predictable sequence: artwork approval, plate and die making, printing, die-cutting or slotting, gluing and packing. Plate and die making usually takes a few days. Printing and conversion run quickly once set up. For reorders, plates and dies already exist, so lead times are shorter. Plan first orders with enough time for platemaking and any adjustments after the first proof.

Specification checklist for flexo printing

• Board grade, flute and liner color (kraft, mottled white, white).
• Number of colors, with Pantone references.
• Print sides (outside, inside or both).
• Artwork on the correct dieline, respecting minimum line weights.
• Barcode orientation, size and quiet zones.
• Quantity, delivery date and reorder plans.

More flexo FAQ

How many colors can flexo print?

Flexo presses for corrugated commonly print one to four colors, and some print more. Most shipping box designs use one or two colors for cost and clarity.

Can flexo print photographs?

Yes, with process color, especially on pre-print and smoother boards. On post-print corrugated, photographs look softer than on offset or digital.

Do I pay for plates again on reorders?

No, if the artwork is unchanged and plates are kept in good condition. Only changed colors or designs need new plates.

Quick decision guide: is flexo right for this job?

Design tips that make flexo shine

• Use bold logos and clear typography that reads from a distance in warehouses and on doorsteps.
• Use the kraft color as part of the design rather than trying to cover it.
• Choose one strong brand color and one neutral rather than many colors.
• Use patterns that hide minor scuffs from transit.
• Keep fine details and small text for labels rather than box print.

How to brief us on a flexo job

Flexo jobs are quoted on plates, dies and run size. Send:

• Box style, size and board. Including liner color.
• Colors. Number of colors and Pantone references.
• Quantities and reorder plans. Plates and dies are reused.
• Artwork. Vector logos and any patterns.

Send what you have, even if some answers are rough. Our specialists reply within one business day with recommendations, a price estimate and next steps, and every order includes free design help and a 3D proof before anything goes to production.

Flexo in one paragraph

Flexographic printing is the workhorse of shipping box printing: fast, consistent and economical at volume, especially with one or two bold colors on kraft or white corrugated. Plates and dies are reused for reorders, making flexo increasingly cost-effective over time.

Corrugated prices with one- and two-color print

Flexo is the workhorse for simple, bold corrugated graphics. Estimated unit prices with one-color print:

A dash means the quantity is below that style’s minimum. Prices are estimates from our published model; the actual print process is chosen for your run length and design.

How to order flexographic printing

1. 1Request a quote

   Tell us the style, size, quantity and artwork you have. Use the form or the live estimator.

2. 2Free design & dieline

   We send a dieline for your exact size, check your artwork and help with layout at no charge.

3. 3Approve your proof

   Review a digital 3D proof (and an optional physical sample) before anything is printed.

4. 4Production & QC

   Your boxes are printed, finished, die-cut and inspected against the approved proof.

5. 5Delivered to your door

   Shipped flat-packed with tracking to any address in the contiguous US.

Written and reviewed by the CustomPacka Packaging Team · Updated October 21, 2026