Duplex paper and laminated paper: understand the composition to make the right choice
Duplex is the foundation of most folding boxes in Vietnam. Knowing the difference between grey back and white back will help avoid costly rework.
Duplex paper is a multi-layer board, with a white coated surface for printing and a gray or white back depending on the type, used for folding boxes for food, pharmaceuticals, and cosmetics. Coated paper is a thick board made from multiple layers, creating a rigid box that does not fold on its own, typically used for gifts and premium packaging. These two types are suitable when you need a box that maintains its shape well at a reasonable cost for medium to large production.
- food folding box
- medicine and pharmaceutical box
- hard gift box
- mid-range mass cosmetics
- needs to block moisture or retain fragrance
- need to print or expose the back using grey back
Most folding boxes in Vietnam, from cake boxes to medicine boxes to affordable cosmetic boxes, use duplex paper as the core. This material is so common that many people order boxes without knowing what they are using. Understanding the composition will prevent situations where the inside of the box is gray after printing, or the box is too thin to hold its shape.
What are duplex paper and cardboard?
Duplex paper (duplex board) is a multi-layer paperboard: the top side is coated white for printing, while the back has two main variants. Grey back uses recycled fibers in the bottom layer, is cheaper, and more common in regular folding boxes. White back looks better, can be printed on both sides, and is often used when the inside of the box needs to be displayed.
The common weight of duplex board ranges from 230 to 450 gsm depending on the paper grade and supplier. This figure is only a reference when discussing with the printer, not a strict technical specification. The actual thickness (caliper, measured in micrometers) also depends on each specific production batch.
Paperboard is the next step: multiple layers of cardboard are glued together to form a thick, sturdy sheet, then wrapped in printed or art paper. The result is a rigid box, which is a type of box that cannot fold itself and must be manually assembled. Premium phone boxes, wine boxes, and perfume boxes are typical examples.
When to choose, when not to
Duplex is a reasonable choice when you need a sturdy folding box that maintains its shape well, with a medium to large production volume, and a budget that is not in the luxury segment. Food packaging, pharmaceutical boxes, and common to mid-range cosmetic boxes are all suitable for duplex. Coated paper is appropriate when upgrading to a premium rigid box, such as for corporate gifts, product launches, or high-end cosmetics.
- Strengths: Sturdy, maintains stable form. Grey back significantly reduces costs for large volumes. Recycled fiber core is more environmentally friendly than virgin paper. Offset printing on white surface for sharp colors. Easy to further process: lamination, foil stamping, die-cutting.
- Limitations: Grey back cannot be printed on the back; the inside of the box will be gray if not lined additionally. Duplex is not moisture-resistant or odor-retaining; a lining is necessary if the product comes into contact with moisture or oil. Rigid boxes require manual lining, resulting in longer production times and higher labor costs compared to folding boxes. Foil stamping or plastic lamination reduces recyclability.
Do not choose duplex grey back when the inside of the box is exposed and needs to look good. Do not use unlined duplex boxes to directly hold food that has moisture or oil. If you need a refined luxury tactile feel, coated art paper would be more suitable. If moisture, gas barrier, or airtight sealing is required, composite films are the right direction.
Costs, time and quantity
The minimum quantity depends on the printer and the type of box. Folding boxes are usually more flexible, allowing for smaller runs than rigid boxes. Rigid boxes typically have higher minimum quantity requirements due to preparation costs and manual lining labor.
Sinh Vũ does not guarantee printing prices and does not represent the printing house.
One point to note: the folding box requires a dieline that matches precisely with the printer's die-cutting machine. If the design file does not match, the printer will have to make adjustments, which may incur additional costs. Therefore, it is advisable to request the die specifications from the printer before finalizing the layout.
What do you need to prepare before placing the order?
To choose the right type of duplex and outline the appropriate box structure, you need to have the following ready:
- Number of SKUs to be designed and the dimensions of the products inside (length, width, height, weight)
- Type of product: food, pharmaceuticals, cosmetics, or gifts, as each industry has different labeling requirements according to Vietnamese regulations.
- Does the inside of the box show when opened, to determine if it has a grey back or white back?
- Projected yield per print run and total annual demand
- What is the budget and timeline needed for the completed file?
- Have you chosen a printing house yet, or do you need to find more to compare?
With all the information above, selecting the box structure, type of paper, and working process with the printer will be more specific and require fewer revisions.
Decision checklist
Topic: Duplex paper and laminated paper. Sinh Vũ guide, sinhvu.com
Select each item you find appropriate, then print or save as PDF to take with you.
If you have marked most of the signs above, this is the time to discuss in more detail. Sinh Vũ can help you review and propose a direction.
References
ChinaPaperGroup, Duplex Board Explained: Grey Back vs White Back. GreyPaperBoard, Duplex Paper Board Manufacturer. PakFactory, Clay Coated Newsback Duplex Paperboard. Practical experience from Sinh Vũ Studio.
Frequently asked questions
What is the difference between grey back and white back, and which one is cheaper?
Grey back has a gray recycled fiber backing, which is cheaper and sufficient when the inside of the box is completely concealed. White back has a white backing, looks better, can be printed on both sides, and is suitable when customers can see the inside. If the budget is a priority and the inside is not visible, grey back is a reasonable cost-saving choice.
Does a duplex box protect moist or oily food?
No, duplex board is a secondary layer, meaning it is a protective and display layer on the outside, not the layer that comes into contact with food. If the product has moisture or oil, an additional lining or filter bag inside is necessary. The appropriate box structure depends on the product's characteristics, so those characteristics should be confirmed before selecting the structure.
How long does it take to produce a rigid box compared to a regular folded box?
Rigid boxes require a manual lining process, so the production time is longer than that of standard folding boxes. Duplex folding boxes are typically completed significantly faster. The specific timeframe depends on the printer and actual quantity, so ask the printer before confirming the schedule.
This article is for reference. The scope, pricing, and specific commitments of Sinh Vũ are detailed in the proposal and signed contract.