The Importance of Kraft Paper Selection for Paper Bags
Every paper bag begins with a roll of kraft paper — but not all kraft paper is the same. The grade you choose determines the strength of the bag, how it prints, how it feels in the hand, what it costs, and whether it can hold a hot croissant or a heavy bottle of olive oil. Manufacturers who understand paper — the types, the GSM scale, the coatings, and the strength characteristics — produce better bags, quote more accurately, and avoid the two classic mistakes: using paper that is too weak (bags that tear and destroy your reputation) or too heavy (cost overruns that destroy your margin). This guide gives you the practical material knowledge every paper bag manufacturer needs.
Common Types of Kraft Paper for Bag Production
The two workhorse materials of the bag industry are natural (brown) kraft and white (bleached) kraft:
Brown kraft is unbleached, made from wood pulp that retains its natural brown color and long fibers. It is the strongest paper per gram of weight, the cheapest, and the classic look of eco-friendly packaging. Brown kraft is the default choice for bakery bags, takeaway bags, and shopping bags where the natural aesthetic is part of the appeal.
White kraft is bleached to a bright white color, offering a clean, premium surface for printing. It costs more than brown kraft and is slightly weaker per gram because bleaching shortens fibers slightly. White kraft is chosen when brand colors must appear true and vivid — coffee roasteries, cosmetics, and premium retail favor it.
A useful middle option is pre-coated or natural white kraft — brown kraft with a white mineral or clay coating on one or both sides. It prints nearly as well as white kraft at a lower cost and higher strength, which is why many mid-market shopping bags use it.
GSM Standard and Practical Selection Rules
GSM — grams per square meter — is the universal measure of paper weight. It directly determines bag strength, feel, and cost. Here is a practical guide for bag production:
30–45 gsm: Lightweight. Suitable for very small bags, tissue-style wrapping, and light single-item carry (a small pastry, a handful of produce). Runs fast on machines, but offers little structural strength.
50–70 gsm: The everyday workhorse. Ideal for standard bakery bags, fast-food bags, and small shopping bags. This range accounts for the majority of square bottom and sharp bottom bag production.
70–100 gsm: Medium-heavy. The standard for retail shopping bags with handles, coffee bean bags, and packaging that must carry several kilograms. Combines good strength with a premium feel.
100–120+ gsm: Heavyweight. Used for large shopping bags, wine and gift bags, and industrial packaging. Requires machines rated for heavyweight paper — confirm the maximum before buying.
Fiber type. Softwood (long-fiber) pulp gives tear and tensile strength; hardwood (short-fiber) pulp gives smoothness and printability. Kraft paper is mostly long-fiber, which is why it outperforms recycled or mixed papers at the same GSM.
Wet strength. Standard kraft loses most of its strength when wet. Wet-strength treated kraft resists moisture for chilled or frozen food applications.
Functional Coatings and Paper Treatments
Water-based barrier coatings: Provide grease and moisture resistance without plastic, appealing to eco-conscious food brands.
Each treatment adds cost, so apply them only where the application demands it: PE coating for greasy takeaway, barrier coating for bakery bread (keeps the bag from going soft), and no coating at all for simple dry-goods bags.
1. Order samples and test, don't trust spec sheets alone. Run a sample reel on your machine at full speed. Check: does it feed cleanly, fold precisely, glue reliably, and print well? Paper that jams or creases costs more in waste than any price discount saves.
4. Control storage conditions. Kraft absorbs moisture: store rolls in a dry warehouse (under 60% humidity), and use the oldest rolls first. Moisture-damaged paper is the silent cause of many production problems.
Paper is the largest variable cost in bag manufacturing and the single biggest influence on bag quality. Understand the difference between brown and white kraft, choose GSM by the bag's job rather than habit, look beyond weight to strength properties, apply coatings only where needed, and build disciplined material handling — and you will produce stronger bags, lower your waste, and quote more profitably.