Ir al contenido Kangchuang Paper’s sulfur-free packaging paper is a factory-manufactured, low-sulfur specialty paper (<5ppm sulfur content) designed for wrapping, interleaving, and packaging silver, copper, brass, bronze, and plated metal components that require protection from hydrogen sulfide tarnishing during long-term storage, ocean freight transit, and warehouse holding. Unlike standard packaging paper or generic acid-free tissue — which may control pH but contain sulfur residues from pulping chemistry that off-gas tarnish-causing H₂S gas — our sulfur-free wrap is specifically manufactured and batch-tested to prevent sulfide-driven discoloration of precious metal surfaces, plated finishes, and bare copper contacts. Available in standard widths of 300mm, 500mm, 800mm, and 1,000mm or any custom dimension from 20mm to 1,600mm, in paper weights from 35gsm to 150gsm. Factory-direct from Dongguan, China — free samples shipped via DHL Express to United States buyers.
The most common misconception among industrial buyers is that ‘acid-free’ and ‘sulfur-free’ mean the same thing, or that acid-free paper automatically provides anti-tarnish protection. They do not. These are two independent paper specifications addressing two different chemical degradation mechanisms.
Acid-free paper is defined by its pH value — neutral (pH 7) to slightly alkaline (pH 8–9) — and is produced without acidic sizing agents (alum-rosin) that generate sulfuric acid as the paper ages. Acid-free paper prevents the acidic degradation of cellulose fibers and the acid-driven corrosion of metal surfaces it contacts. This is the primary specification for archival document storage and certain metal packaging applications.
Sulfur-free paper is defined by its sulfur content — typically specified as <5ppm total sulfur — which controls the emission of hydrogen sulfide (H₂S) gas from the paper. Sulfur enters paper during the kraft pulping process (which uses sodium sulfide as a cooking chemical) and is difficult to fully remove. Even papers made by alkaline papermaking (acid-free by pH) can contain significant sulfur residues that off-gas H₂S and tarnish silver, copper, and other reactive metal surfaces.
For comprehensive metal protection — particularly for silver and copper, which are highly reactive with sulfide gases — both specifications are required simultaneously. Kangchuang’s sulfur-free packaging paper achieves: pH 7.0–8.5 (acid-free) AND <5ppm sulfur (sulfur-free). This dual specification is what distinguishes electronics-grade and precious-metal-grade packaging paper from generic ‘neutral tissue’ or ‘acid-free wrap’.
Electronics Manufacturing: Wrapping silver-plated SMD brackets, LED lead frames, gold-plated connector pins, copper bond wire assemblies, and bare-copper PCBs during inter-facility shipment, warehouse storage, and component staging before assembly.
Silver Jewelry and Silverware: Wrapping individual pieces and interleaving between stacked items in retail packaging, transit packaging, and long-term storage display boxes where H₂S tarnish from standard tissue paper would require polishing before sale.
Copper and Brass Industrial Hardware: Wrapping copper busbars, bus duct segments, machined brass fittings, and valve bodies for extended storage before installation. Standard kraft or newsprint packaging causes rapid surface oxidation of copper and brass during multi-month storage.
Precision Instrument Components: Packaging optical mirror mounts with silver-coated reflective surfaces, precision weight standards with polished metal surfaces, and laboratory instruments with silver-brazed components requiring surface chemistry integrity.
Automotive Electronics Supply Chain: Wrapping silver-plated connectors, tin-plated terminals, and copper wire harness assemblies for ocean freight shipment from Asia to North American and European assembly plants.
35–50gsm Tissue Grade: Lightweight interleaving for fine jewelry, small electronics components, and precision optical components where minimum bulk addition and maximum flexibility are required. Suitable for manual wrapping of individual items and interleaving between component layers in rigid trays.
60–80gsm Standard Grade: All-purpose industrial wrapping for hardware components, electronic assemblies, and packaged goods requiring a balance of flexibility and tear resistance. The most commonly specified grade for general anti-tarnish packaging applications.
100–150gsm Heavy Grade: Reinforced outer wrap for heavy hardware, large copper assemblies, and applications where the paper must provide mechanical protection in addition to chemical protection during rough freight handling.
| SPECIFICATION | DETAILS |
| Sulfur Content | <5ppm — XRF analysis verified per production batch |
| pH Value | 7.0–8.5 (acid-free with alkaline reserve) |
| Available GSM Grades | 35gsm | 45gsm | 60gsm | 80gsm | 100gsm | 120gsm | 150gsm |
| Roll Width Range | 20mm to 1,600mm — custom slit to specification |
| Sheet Sizes Available | A4 (210×297mm) | A3 (297×420mm) | Custom cut sheets on request |
| Width Tolerance | ±0.5mm for roll widths up to 500mm | ±1.0mm for widths 500–1,600mm |
| Color | Bright white (bleached) | Natural cream (semi-bleached) | Unbleached kraft-tone on request |
| Core Diameter | 3-inch (76mm) standard | 6-inch (152mm) | Custom on request |
| Roll Length | 500m–5,000m per roll depending on gsm and width | Customer-specified |
| Tensile Strength | ≥1.2 kN/m (MD) for 35gsm | ≥2.8 kN/m (MD) for 80gsm |
| Moisture Content | 5–8% at 23°C / 50% RH |
| Packaging | Rolls in polyethylene sleeve | Sheets in ream wrapping or carton |
| MOQ | 2 rolls / 1 ream for sample evaluation | 500kg for production orders |
| Lead Time | 5–7 days (samples) | 7–12 days (standard production) |
| Shipping | DHL Express (USA samples — free) | FOB Dongguan sea freight (production) |
| Documentation | Sulfur test report | pH certificate | Batch traceability record |
Sulfur-free packaging paper is a specialty paper manufactured with sulfur content below 5 parts per million (ppm) — a threshold established by the electronics and precious metals industries to prevent hydrogen sulfide gas from off-gassing from the paper and tarnishing reactive metal surfaces. Regular paper (kraft, newsprint, standard tissue) is produced by pulping wood with sodium sulfide as a cooking chemical, leaving sulfur residues in the finished sheet. These sulfur residues emit H₂S gas under ambient conditions that reacts with silver, copper, and certain plated surfaces to form dark metal sulfide tarnish. Sulfur-free paper removes or reduces these sulfur residues to below the threshold at which harmful H₂S emission occurs.
No — acid-free and sulfur-free are two different and independent paper specifications. Acid-free paper has a neutral or alkaline pH (typically pH 7–9) that prevents acid-driven cellulose degradation and acidic gas emissions that corrode metals. Sulfur-free paper has <5ppm sulfur content that prevents hydrogen sulfide gas emissions that tarnish silver and copper. Both specifications are needed for comprehensive metal protection. Many acid-free papers contain significant sulfur and will still tarnish silver surfaces. Kangchuang’s sulfur-free packaging paper is both acid-free (pH 7.0–8.5) AND low-sulfur (<5ppm), providing dual protection.
Silver and silver-plated surfaces are the most sensitive to sulfide tarnish and the primary driver of sulfur-free paper specification in electronics and jewelry industries. Copper and copper alloys (brass, bronze) also react with H₂S to form copper sulfide tarnish, though at a slower rate than silver. Gold-plated and tin-plated surfaces can also be affected by sulfur contamination reducing solderability and surface bondability. In practice, any packaging application involving reactive metal surfaces — silver, copper, brass, bronze, or electronics with plated terminals — benefits from sulfur-free paper.
Every production batch of our sulfur-free packaging paper is tested by XRF (X-ray fluorescence) spectroscopy in our quality laboratory before approval for shipment. The test report showing the measured sulfur content in ppm for your specific batch is included with every shipment as a standard document — not on request. For customers requiring third-party laboratory verification, we can arrange independent testing at an accredited external laboratory. We do not claim ‘sulfur-free’ without measurement.
For individual silver jewelry piece wrapping: 35–50gsm tissue grade is ideal — thin enough for folding and wrapping delicate items without adding bulk, with sufficient coverage for tarnish prevention in standard storage conditions. For interleaving between multiple pieces in a tray or box: 35–45gsm tissue provides the separation layer needed. For high-value or delicate silverware requiring additional mechanical protection alongside tarnish prevention: 60–80gsm provides better tear resistance. We can supply a sample of each grade for your evaluation.
Yes. Copper busbars, bus duct segments, and copper cable assemblies are commonly wrapped in sulfur-free paper for storage periods of weeks to months, and for ocean freight transit from manufacturing facilities to installation sites. Without sulfur-free packaging, copper surfaces develop visible oxidation within days to weeks in standard packaging. Our 80–120gsm grades provide both the chemical protection (low sulfur) and the physical protection (heavier weight for handling and stacking of heavy copper components) needed for copper busbar applications.
Sample evaluation orders: minimum 2 rolls (or 1 ream for sheet format) at your specified dimensions — no minimum weight for samples, shipped free via DHL Express to USA. Production orders: minimum 500kg total weight across all grades and widths ordered. Container-load orders (15–20 metric tons) receive our best FOB pricing and fastest lead times from maintained inventory.
Yes. We supply sulfur-free packaging paper in pre-cut sheet format as well as rolls. Standard sheet sizes are A4 (210×297mm) and A3 (297×420mm). Custom sheet sizes to any dimension are available for orders above 500kg. Sheets are supplied in ream packaging (500 sheets per ream) or in carton packs for bulk orders. Sheet format is popular for manual wrapping operations, retail packaging inserts, and applications where roll-fed equipment is not available.
Yes, for orders above 3,000kg we offer custom printing on sulfur-free packaging paper — company logo, product code, handling text, or regulatory markings. Print inks used on sulfur-free paper must themselves be low-sulfur to avoid re-introducing sulfide contamination to the paper surface. We verify ink sulfur content before use and use water-based, low-VOC inks compatible with the anti-tarnish paper specification. Contact us with your artwork and order volume for a printing quote.
Store sulfur-free packaging paper in its original polyethylene sleeve or carton wrapping in a clean, dry warehouse environment: temperature 15–30°C, relative humidity 30–65%, away from direct sunlight, chemical storage, and any sulfur-containing materials (rubber products, certain adhesives, industrial chemicals). Do not store near kraft paper or standard newsprint, which off-gas sulfide compounds that could contaminate the sulfur-free paper over time. Properly stored, our sulfur-free packaging paper maintains its specification for 24 months from production date.
Kangchuang Paper operates under ISO 9001 quality management certification. Our manufacturing processes include documented procedures for incoming material inspection, in-process quality monitoring (pH, conductivity, caliper), and finished product testing (sulfur content, pH, tensile strength). Batch traceability from incoming pulp through finished roll is maintained for 3 years. We can provide our ISO certificate and a supplier qualification questionnaire for buyers conducting formal supplier audits.
Yes. We supply sulfur-free packaging paper to industrial buyers, packaging converters, electronics manufacturers, jewelry companies, and hardware distributors throughout the United States. Sample rolls ship via DHL Express (3–5 business days to most US locations) at no charge. Production orders ship FOB Dongguan by sea freight. We provide all standard export documentation (commercial invoice, packing list, certificate of origin, and material test reports). Contact us with your specification and US delivery location for a full delivered cost estimate.
Kangchuang Paper specializes in high-quality industrial papers — sulfur-free, coated, release, and anti-rust. Tell us your requirements and we’ll recommend the right grade with fast turnaround.
