Woodfree offset printing paper is an uncoated paper made from chemically pulped fibre and designed to run on offset presses. It is the sheet behind most books, forms, stationery, manuals and many label face papers. The name causes confusion, because "woodfree" does not mean the paper contains no wood.
All paper starts as plant fibre, and most of it is wood. "Woodfree" refers to how the fibre was processed. Chemical pulping dissolves most of the lignin, the natural binder that holds wood together. Lignin is what makes newsprint turn yellow and brittle in sunlight. In the trade, a sheet is usually called woodfree when it contains little or no mechanical (groundwood) pulp, commonly under about 10%. Strictly speaking, "mechanical-pulp-free" would be the more accurate label.
Removing lignin gives woodfree paper its three defining traits: a cleaner, brighter sheet, better resistance to yellowing, and higher strength for a given weight. These are the reasons printers and converters choose it over cheaper wood-containing grades.
| Property | Woodfree uncoated | Wood-containing (e.g. newsprint) | Woodfree coated (art / gloss) |
|---|---|---|---|
| Pulp | Chemical | Largely mechanical | Chemical, with a mineral coating |
| Ageing / yellowing | Slow | Fast | Slow |
| Writable by pen | Yes | Yes | Limited |
| Colour vibrancy | Moderate, natural look | Low | High |
| Relative cost | Medium | Low | Higher |
Four production choices shape how a sheet behaves in the pressroom:
Because the sheet is uncoated, ink dries mainly by soaking into the fibre network rather than sitting on a sealed layer. That brings two practical consequences. Dot gain is typically higher than on coated paper, often 20% or more at midtones, so uncoated-specific colour profiles and press curves are needed. Total ink coverage limits are also usually lower than for coated sheets. Printers who reuse a coated-stock setup on uncoated paper often get muddy images, and the paper gets blamed for what is really a calibration problem.
Datasheets list many numbers, but only a few drive real-world results. The table below shows the standard range of Guanhao's General Purpose Woodfree Offset Printing Paper, the test method behind each figure, and what it means in practice.
| Parameter | Standard range | Test method | What it means for you |
|---|---|---|---|
| Grammage | 60 – 120 gsm | ISO 536 | Weight per square metre; drives feel, stiffness and postage cost |
| ISO brightness | 80 – 95% | ISO 2470 | Reflectance of blue light; higher gives stronger contrast |
| Opacity | ≥ 85% | ISO 2471 | Limits show-through on double-sided jobs |
| Smoothness (Bekk) | 80 – 200 s | ISO 5627 | Higher is smoother; helps fine text and halftones |
| Moisture content | 4% – 6% | ISO 287 | Keeps the sheet flat; large swings cause curl and misregister |
| Sheet sizes | A4, A3, SRA3, custom; rolls available | – | Custom cutting avoids trim waste |
| Packaging | 500-sheet reams, bulk cartons, rolls | – | Moisture-proof wrapping protects flatness |
| Storage | 18 – 25 °C, 45 – 65% RH | – | Away from direct sunlight; keep in original wrap until use |
Brightness is not whiteness. ISO brightness measures only one narrow band of blue light. Two sheets with the same brightness can look different because of optical brightening agents or shade. Judge both under the same lighting before approving a job.
Higher brightness has a trade-off. Extra whitening adds cost. It also does little for text-heavy jobs where a slightly softer white is easier on the eyes. For long reading material, 80–90% is often the more comfortable choice.
Test conditions matter. Paper properties are measured after conditioning at 23 °C and 50% relative humidity (ISO 187). If your pressroom is hotter, colder or more humid, results will differ from the datasheet. Always test in your own environment.
| Grammage | Feel | Typical uses |
|---|---|---|
| 60 – 70 gsm | Light, flexible | Inserts, forms, lightweight logistics labels |
| 75 – 80 gsm | Standard office weight | Stationery, letterheads, A4 flat sheet labels |
| 90 – 100 gsm | Medium, opaque | Brochures, manuals, drug labels |
| 105 – 120 gsm | Heavy, premium | Reports, posters, covers, retail shelf labels |
A useful rule of thumb: if show-through is the concern on a double-sided job with heavy ink coverage, increase weight or opacity before increasing brightness. If the job will pass through a desktop laser printer or a high-speed web press, check that the weight sits inside the machine's rated range.
Woodfree paper is also the most common face material for self-adhesive labels. The same properties matter, with extra requirements: the sheet must stay flat through silicone and adhesive coating, accept laser or thermal-transfer print, and be die-cut cleanly. For the label-ready versions, see Guanhao's woodfree adhesive range, including Basic Woodfree Paper, General Purpose Woodfree Paper and Removable Woodfree Paper Label.
| Feature | Woodfree | Copperplate (coated) | Thermal | Film |
|---|---|---|---|---|
| Surface | Matte, uncoated | Gloss / semi-gloss | Heat-sensitive coat | Gloss or matte film |
| Handwriting | Yes | Partial | Limited | No |
| Water resistance | Low to moderate | Moderate | Low to moderate | High |
| Colour print quality | Good | Excellent | Basic | Excellent |
| Cost | Economy | Mid-range | Economy | Premium |
Match the paper to the label's working life. For example, logistics, retail and office labels suit woodfree stock. Labels exposed to moisture, oil or outdoor weather usually need film or a protective finish instead.
| Problem | Likely cause | What to try |
|---|---|---|
| Curling or wavy edges | Moisture imbalance | Acclimatise stock; keep packs sealed; check room RH |
| Show-through | Low opacity for the ink load | Raise gsm or opacity; reduce ink coverage |
| Dull or flat colour | Coated-stock profile used on uncoated paper | Use an uncoated profile and recalibrate |
| Dust or lint on blankets | Loose surface fibre or filler | Clean blankets more often; ask the supplier about surface strength |
| Set-off | Ink not yet dry in tall piles | Lower pile height; adjust ink and drying |
| Static or double feeding (laser) | Very dry air | Fan the stack; raise humidity toward 45–65% RH |
Chemical pulp is compatible with FSC-certified supply chains. If certified paper matters to your customers, request chain-of-custody documentation with your order, because certification applies to specific supply routes and not to a paper grade as a whole (see fsc.org). For documents that must last, look for acid-free, alkaline-buffered stock that meets ISO 9706 (permanence of paper), which sets requirements for pH, alkaline reserve and low lignin content.
Zhejiang Guanhao Functional Material Co., Ltd. is a wholly owned subsidiary of Guangdong Guanhao High-tech Co., Ltd. (stock code 600433), which is owned by China Paper Investment Co., Ltd. According to the company's About Us page, it operates four self-adhesive material production lines across two bases (Zhejiang and Guangdong), with annual capacity of 1.1 billion square metres, and exports to more than 50 countries and regions. Its quality system has passed ISO 9001 certification, and its products have passed RoHS environmental testing by SGS. Production is monitored from raw material inspection through silicone coating, adhesive coating, slitting and shipment.
Is woodfree paper really made without wood?
No. It is made from wood fibre that has been chemically pulped, so most lignin is removed. "Woodfree" is a trade term for the absence of significant mechanical pulp.
Can I use it on a desktop laser or inkjet printer?
Yes. Woodfree uncoated sheets accept laser toner, most inkjet inks and ballpoint pens. Check your printer's supported weight range first.
When should I choose coated paper instead?
Choose coated stock when photographic colour, gloss and fine detail are the priority, such as premium brochures or cosmetic packaging. Choose woodfree when readability, writability and economy matter most.
Can I order custom sizes or weights?
Yes. Custom weights, dimensions and roll formats are available on request. Minimum order quantities depend on the product, so ask the sales team for current terms.
