Warming up guide brochure (pdf) - Metsä Board

WARMING UP
GUIDE
WARMING UP GUIDE FOR
PAPERBOARD
Paperboard should have the same temperature as
the print room before being unwrapped. If sheets or
reels are moved from a cold warehouse to a warm print
room, any unwrapped edges may absorb humidity
from the air and expand. These edges may become
wavy, causing creases to occur during printing or
converting. Cold paperboard may also result in print
mis register, or affect ink-setting in offset printing.
Metsä Board's fresh forest fibre paperboard is manufactured to
optimal moisture content for perfect print and converting results.
To maintain this moisture content, the material is packed in a
moisture-proof wrapper, which protects it during shipment, delivery
and storage.
The moisture-proof wrapper should remain sealed until the
paperboard has warmed up to room temperature. The recommended
relative humidity of press and converting rooms is 50 to 55% and
the temperature 20 to 23° C

for optimum results, let paperboard warm up
before unwrapping
How long does it take for the paperboard to warm up
The warming-up time depends on the pallet or reel
weight and the temperature. The enclosed table indicates
how long the pallets or reels should be stored at room
temperature before being unwrapped.
To work out the required warming-up time, refer to
either the weight or the shortest dimension of the pallet
or reel, and to the difference in temperature between
the paperboard (or the warehouse) and the print room.
If the weight and the shortest dimension indicate different
warming-up times, the shorter time can be chosen.
Warming-up time of paperboard pallets or reels (hours)
Weight or Shortest
dimension
temperature difference (°C)
KG mm 5° 10° 15° 20° 25° 30° 35° 40°
200 650 10 30 45 60 75 85 95 100
400 700 15 35 50 65 80 90 100 105
600 750 20 40 55 70 85 95 105 110
800 800 25 45 60 75 90 100 110 115
1000 850 25 50 65 80 95 105 115 120
1200 900 30 55 75 90 105 115 125 130
1400 950 35 60 85 100 115 125 135 140
1600 1000 40 70 95 110 125 135 145 150
Metsä Board is Europe’s leading producer of fresh forest fibre cartonboards, the
world’s leading manufacturer of coated white-top kraftliners, and a major paper
supplier. It offers premium solutions for consumer and retail packaging, graphics
and office end-uses. The company’s sales network serves brand owners, carton
printers, corrugated packaging manufacturers, printers, merchants and office
suppliers. Metsä Board is part of Metsä Group.
metsaboard.com