Applications
Kraft paper for sacks
A paper sack is two or more plies of kraft, formed into a tube and closed at the ends. Our kraft suits bag and sack converting where tear strength decides. Heavy filling lines call for specialist sack kraft.
01 / The build
How a paper sack is built
A multiwall sack stacks two or more plies of kraft into a tube. The ends close by pasting, by sewing, or with a valve the filling spout enters.
Sacks carry cement, chemicals, fertiliser, animal feed and food. The fill is heavy, and the sack takes drops and stacking on the way to the user.
02 / The ply
What a sack ply needs
Strength comes first. The kraft process keeps fibres long, and fibre length drives most of the tear and burst strength.
Sack mills also make extensible sack kraft, built to stretch before the paper breaks, so the sack absorbs the shock of a drop. Lines filling powders also need porous paper, so air escapes as the sack fills.
03 / Grades
Grades for bags and sacks
Pick 1
Kraft
60–120 GSM
Long-fibre, unbleached kraft, listed for bags and sacks where tear strength decides.
- Reel widths
- 600–1,800 mm
- Roll lengths
- 1,000–3,000 m
- Sheet sizes
- 700×1,000, 900×1,200 mm
- MOQ
- 1 tonne per GSM/width
- Lead time
- 3–6 weeks after spec approval
- Food contact
- Not for direct contact. Use butter paper or OGR.
Pick 2
Bleached Kraft
60–120 GSM
Bleached kraft for an outer ply carrying print or a clean white look.
- Reel widths
- 600–1,800 mm
- Roll lengths
- 1,000–3,000 m
- Sheet sizes
- 700×1,000, 900×1,200 mm
- MOQ
- 1 tonne per GSM/width
- Lead time
- 3–6 weeks after spec approval
- Food contact
- Ask us before food use
Figures from the KEIKO PAPERS specification sheet. See every paper grade
04 / Fit
Where our kraft fits
Our kraft is a general strength grade from 60 to 120 GSM. We have not verified extensibility or porosity figures for our kraft, and we do not sell the grade as sack kraft.
This puts our kraft in paper bags, small sacks and outer wraps, where the converter sets and runs the tests. For high-speed filling of cement or fertiliser, buy a specialist sack kraft.
05 / Testing
Before you specify
Send us the fill, the fill weight, the ply count and the filling method. We will send samples for a trial on your line.
Run drop and stacking tests on filled sacks before you set a standard.
06 / Ordering
Formats and order size
Kraft reels run 600 to 1,800 mm wide and 1,000 to 3,000 m long. The MOQ is 1 tonne per GSM and width, with 3 to 6 weeks after spec approval.
Our kraft is not for direct food contact. For food fills, ask us before you specify any ply against the food.
Questions
Before you specify
Is your kraft paper sack kraft?
No. We supply a general long-fibre kraft from 60 to 120 GSM. We have not verified extensibility or porosity figures for sack filling lines.
What weight of kraft for paper bags?
The weight follows the load. Light bags sit towards 60 GSM. Heavier loads point towards 120 GSM.
Do you supply kraft reels for bag makers?
Yes. Reels run 600 to 1,800 mm wide and 1,000 to 3,000 m long, from 1 tonne per GSM and width.