The blanket is the transfer medium that touches plate, sheet and ink directly, the third printing surface of offset. China blanket market value is expected to pass RMB 4.5 billion in 2026 with compound growth of 6 to 8 percent a year, and uneven consumable quality shows up more in peak seasons. When a used press produces weak images, barring or uneven ink density, do not rush to reset pressures or clean the ink rollers: the fault is often in the blanket itself.
- Lost highlights and washed-out images: glazed or photo-oxidised surface with reduced transfer capability.
- Periodic barring: local crush or swelling causing pressure to rise and fall.
- Ink density drifting: glazing unbalances surface ink affinity.
- Excessive thickness difference between corners and centre: creep ageing destroys flatness.
1. Three signals on the sheet that mean a new blanket
Look at dot reproduction: comparing recent sheets from the same plate, weak midtones and missing fine dots that extra ink cannot recover usually indicate surface glazing. Look at barring: periodic light and dark bands matching cylinder rotation, where stopping the press and feeling the blanket reveals hard spots or swelling. Look at ink consistency: with the same plate and ink, density that drifts and briefly improves after washing shows that surface affinity has become unstable.
2. Three checks on a stopped press
First, thumb pressure and recovery: a new blanket rebounds quickly, an aged one responds slowly and keeps a mark. Second, visual surface check: hold it to the light along the weave for cracking, and note glazed areas that look glossy and hard. Third, thickness measurement: measure corners and centre with a micrometer; a difference above 0.03 mm, an empirical reference subject to the machine manual, calls for replacement, and check that total packing thickness is within specification.
3. Fitting and daily care
Keep the same packing when fitting a new blanket and do not add or remove shims at random. Tighten clamp screws diagonally in stages, then fully, and re-tighten once after about five minutes of running when the fabric has settled. For daily care, wash every shift with a dedicated cleaner and never leave strong solvent on the surface; release the impression if the press will stand for more than eight hours to avoid permanent marks in the print zone; and store spare blankets flat, away from light, radiators and direct sun.
Conclusion: The blanket is a low-cost, high-return maintenance item: wash every shift, check recovery and thickness weekly, and replace it when the printed signals appear rather than repeatedly adjusting the press afterwards. On a used machine, fit a new blanket and calibrate printing pressure first as the baseline for whole-machine acceptance.
