90g Butter Paper Industry Standard for Engineering Copying and Blueprint
90 g/m² butter paper is the classic standard specified in GB/T 1468‑2011 for engineering drawing reproduction. With transparency ≥66%, tearing resistance ≥240 mN, and smoothness 13s, it offers the best combination for manual tracing, diazo blueprinting, and long‑term archival storage. Its dimensional stability (MD stretch 4.5%) ensures accurate scale reproduction.
| Parameter | Unit | Value |
|---|---|---|
| Basis Weight | g/m² | 90 (±5%) |
| Transparency | % | ≥66 |
| Tearing Resistance | mN | ≥240 |
| Smoothness (Bekk) | s | ≥13 |
| Machine Direction Stretch | % | 4.5 |
| Cross Direction Stretch | % | 15.0 |
| Sizing Degree | mm | ≥1.5 |
| Moisture Content | % | 7.0±1.0 |
90g paper uses the same acid‑free high‑viscosity beating (≥90°SR) but with optimized fiber blend (75% softwood, 25% hardwood). The stock is formed at 0.6‑1.0% consistency, then pressed and dried at low temperature. Semi‑dry calendering at 100 kN/m linear pressure compacts the sheet. Surface sizing with formaldehyde‑free biological glue ensures water resistance. Final moisture balanced at 6‑8% to prevent curl.
- Engineering Drawing Reproduction – The go‑to weight for manual tracing and master drawing creation.
- Diazo Blueprint Making – Ideal base paper for ammonia‑based blueprint machines; light‑fast and stable.
- Architectural Archiving – Long‑term storage without yellowing or brittleness.
- CAD Plotting – Compatible with wide‑format inkjet plotters; high tear resistance.
90g is the industry benchmark – proven reliability for professional engineering and architectural workflows.
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