DIT PACKAGING / CUSTOM FLEXIBLE PACKAGING
Custom printed center-seal bags
DIT Packaging supplies custom printed center-seal bags with a longitudinal back seam, in flat or gusseted constructions subject to specification review. Request premade bags with an agreed filling opening, or printed rollstock for your forming and filling equipment. Send your product, dimensions and quantity to start a quotation.
At a glance
- Construction
- A longitudinal back seam with flat or gusseted construction as specified.
- Supply format
- Confirm whether you need premade bags or printed rollstock for your equipment.
- Size to specify
- Finished dimensions, seam layout and the opening used for filling.
- Start your brief
- Product, filling process, quantity with its unit and a reference pack or drawing.
Not sure about a detail? Start with your product and quantity.
Download a blank packaging quotation checklist (.txt) · Fill in what you know and send it to Jack.
Center seal describes the seam; gussets describe the folds
A center-seal or back-seal bag has a longitudinal seam on its back. A side gusset is an expanding fold at the side of a bag. These terms describe different features: a bag can have both a back seam and side gussets. Specify both rather than choosing from the names alone.
| Construction | What to look for | What to specify |
|---|---|---|
| Flat center-seal bag | Back seam without expanding side folds | Finished width and height, back-seam position and open filling end. |
| Side-gusset center-seal bag | Back seam plus folds on both sides | Front width, height and clearly labelled folded or expanded gusset measurements. |
| Three-side seal pouch | Sealed perimeter edges rather than a longitudinal back seam | Three sealed edges, their widths and the edge left open for filling. |
Choose premade bags or rollstock
Premade bags and rollstock are different supplies and require different specifications. With a premade bag, identify which end remains open for filling and which seals are already made. After filling, the remaining opening is closed using the agreed packing process.
With rollstock, the film arrives on a roll for forming, filling and sealing on your equipment. A finished bag size alone is not enough to specify the roll. Send the machine model, its film specification or a reference drawing so compatibility can be reviewed before production.
| Supply format | What you receive | What to confirm |
|---|---|---|
| Premade center-seal bags | Individual empty bags with the agreed back seam and an opening for filling. | Finished size, flat or gusseted shape, filling access, seal layout and quantity per design. |
| Printed rollstock | Printed flexible film supplied on a roll for your equipment to form into packs. | Film width, print repeat, eye marks, unwind direction, roll/core dimensions and order unit. |
Specify the premade bag and its back seam
For premade bags, provide finished outside width × height in millimetres. If side gussets are required, label their dimensions and show how the measurement was taken. Include the intended contents, fill quantity and any space needed for final sealing.
Mark the longitudinal back seam, end seals and open filling edge on the same drawing. Confirm artwork orientation against these features. The front of a bag and its back-seam area have different layout constraints, so front-only artwork is not a complete print specification.
- Identify flat or gusseted construction and label every gusset measurement.
- Show the filled direction, open edge and final sealing area.
- State total laminate thickness and material if known.
- Locate important text away from folds and seals using the agreed production layout.
Gusseted center-seal bag artwork layout reference
This reference shows the gusseted center-seal option. It illustrates how the flat artwork wraps around the front, side gussets and back; flat center-seal bags use a different layout.
Use this image to plan panel placement. Request a dimensioned dieline for your chosen size, with confirmed folds, seals and artwork margins, before preparing production artwork.
- Assign artwork across the front, side gussets and back sections in the order shown.
- Confirm the back-seam position, folds, filling opening and artwork orientation on the approved dieline.
Provide the rollstock and machine details
For rollstock, confirm film width and print repeat with the equipment requirements. Print repeat is the repeated printed layout along the web; it is not the total length of film on a roll. Eye-mark position and artwork direction must also match how the machine reads and handles the web.
Use a diagram for unwind direction and identify the printed side. State the required roll diameter and core dimensions, distinguishing the core’s inner diameter from its outer diameter. Do not assume a universal core or roll size will fit your line.
| Area | Details to send |
|---|---|
| Web and artwork | Film width, print repeat, eye-mark dimensions and position. |
| Orientation | Unwind diagram, printed side and artwork travel direction. |
| Roll and core | Maximum or required roll diameter; core inner and outer dimensions. |
| Packing process | Machine specification, product, filling conditions and sealing requirements. |
Agree material, quantity and production steps
Explain the contents, storage conditions and target shelf life when requesting material options. The laminate must be considered with the packing process. A compatible structure or machine setup for one product should not be assumed suitable for another.
For premade bags, state quantity per design and size. Selected digital-print projects may start from 500 pieces, subject to confirmation of the construction and material. Gravure-printed premade bags start from 50,000 pieces; confirm the applicable order basis in your quotation. For rollstock, agree the quantity unit and minimum separately instead of applying a premade-bag minimum.
Check a premade sample for product fit, filling access and final sealing clearance. For rollstock, arrange a line trial appropriate to your equipment before confirming repeat supply, checking film travel, print registration and seal results with the proposed material. A finished-pack photograph cannot confirm machine compatibility.
Include artwork status, the delivery destination and your desired arrival date. Confirm sample or trial requirements, artwork approval, production timing, payment terms and transport separately. DDP, FOB and CIF can be discussed once the address or named port is known.
YOUR PRODUCT. YOUR SPECIFICATION.
Request a packaging quote
Discuss custom printed center-seal bags with Jack. Start with what you pack and your reply email. Leave undecided details open.
- Tell us your product and quantity.
- We review the format, material and sample options.
- Confirm the specification, price and timing before ordering.
PRODUCTION BEHIND YOUR PACKAGING
Digital and gravure options for your project
DIT Packaging serves overseas buyers, supported by digital production in Guangzhou and gravure production in Shaoguan. The printing route is reviewed against your specification and order plan.
Company-supplied production photos. View our production overview · Read production licenses and their named holders
Buyer questions
How is a center-seal bag different from a three-side seal pouch?
The center-seal format uses a longitudinal back seam. A three-side seal pouch is defined by three sealed edges and one open filling edge. Compare seam placement, product access and the packing method before selecting a format.
Is a pillow pouch a center-seal bag?
Pillow-style packs can use a longitudinal back seam and end seals. The term describes the filled shape rather than a complete specification. Send a drawing to confirm the seam, gussets if required and open filling end; not every center-seal construction has the same shape.
Can a center-seal bag have side gussets?
Yes, a back seam and side folds can be part of the same construction. Label the front width, height, gusset measurements and seam on a drawing. Confirm whether a gusset measurement describes a folded or expanded dimension before artwork preparation.
Are premade center-seal bags supplied closed at both ends?
A premade bag intended for later filling needs an agreed open filling edge. Identify it on the drawing together with the supplied seals; do not assume the filled-pack image shows the condition in which empty bags are supplied.
Can rollstock be ordered using only a finished bag sample?
A sample helps explain the result, but the roll must also meet your machine’s requirements. Provide film width, print repeat, eye marks, unwind direction and roll/core dimensions for review.
YOUR NEXT STEP
Send Jack your packaging brief
Share your product, approximate quantity, bag dimensions and delivery destination. If a detail is undecided, say so; the specification can be reviewed before quotation.
jack@ditpackaging.com · +86 188 9665 3135
Guangzhou DIT Packaging Trading Co., Ltd.
广州迪爱特包装贸易有限公司
Supported by digital production in Guangzhou and gravure production in Shaoguan. See production photos and production licenses with their named holders.