An inquiry arrives asking for NBKP. The desk that receives it quotes BSKP. Both sides think they are talking about different things for a moment, and then someone works out that they are not. It happens constantly, and it is entirely an artefact of two naming conventions that grew up separately.
Where the letters come from
The international convention describes the tree by its wood: softwood or hardwood. So bleached kraft pulp from softwood is BSKP, and from hardwood, BHKP.
The Japanese convention describes the tree by its leaves. 針葉樹 — literally "needle-leaf tree" — is softwood, which gives the N in NBKP. 広葉樹 — "broad-leaf tree" — is hardwood, which gives the L in LBKP.
That is the whole mystery. N is not "northern" and L is not "low-grade". They are needle and leaf, and the two conventions are describing the same two categories of tree from different angles.
| Japanese term | International term | What it is |
|---|---|---|
| NBKP | BSKP | Bleached softwood kraft pulp. 針葉樹晒クラフトパルプ |
| LBKP | BHKP | Bleached hardwood kraft pulp. 広葉樹晒クラフトパルプ |
| NUKP | UKP (softwood) | Unbleached softwood kraft pulp |
| LUKP | UKP (hardwood) | Unbleached hardwood kraft pulp |
An inquiry written in either column is understood here. There is no need to translate before writing to us.
Where the mapping breaks — and this one costs money
The table above is safe. The trap is the next layer, where two very common abbreviations get treated as synonyms for the category and are not.
NBSK is Northern Bleached Softwood Kraft. The N here really does mean northern — pulp from the slow-growing softwood of Canada, the Nordic countries and comparable latitudes. It is a subset of BSKP, not another word for it. Southern bleached softwood kraft from the US South is equally BSKP and equally NBKP, and it is not NBSK.
BEK is Bleached Eucalyptus Kraft — a specific species, predominantly from Brazil and the Iberian peninsula. It is a subset of BHKP. Birch, aspen, acacia and mixed tropical hardwood are all BHKP and none of them are BEK.
NBKP → BSKP is a translation. BSKP → NBSK is a narrowing.
Answering an inquiry for NBKP with an offer of NBSK may be right, or it may be a different product at a different price. Answering an inquiry for NBSK with southern softwood is simply wrong, even though both are BSKP.
This matters commercially because NBSK is the grade most price references are quoted against. A buyer saying "NBSK" may mean the actual northern grade, or may be using it loosely as shorthand for softwood pulp generally. Those are different contracts, and the gap between them is not small.
What the two categories actually do in a sheet
Behind the naming is a real physical difference, and it is the reason mills buy both rather than choosing one.
- Softwood (N / S) fibres are long — typically in the range of 2.5 to 4.5 mm. Length is what builds a fibre network that holds together, so softwood is bought for tensile and tear strength. It is the structural component of the furnish.
- Hardwood (L / H) fibres are short — generally under 1.5 mm, and often around a third the length of softwood. Short fibres pack more densely and more uniformly, giving bulk, better formation, a smoother surface and higher opacity. It is the printability and body component.
Which is why a furnish is normally specified as a ratio rather than a single grade. A mill asking for a change in its N/L ratio is adjusting strength against formation, not switching supplier.
The grades that do not map at all
Not every pulp fits the two-category scheme, and trying to force it causes its own confusion.
- BCTMP is a high-yield chemi-thermomechanical pulp. It is bought for bulk and opacity in board and tissue, and it is neither a softwood nor a hardwood question first — the process defines it.
- Fluff pulp is softwood kraft, but it is specified by absorbency and defibration behaviour for hygiene products, not by the usual strength properties.
- Dissolving pulp is a chemical feedstock measured on alpha-cellulose content. It is not a papermaking pulp at all, and quoting it against paper grades makes no sense.
How to write an inquiry that cannot be misread
Three lines remove the entire problem:
- Category: BSKP / NBKP, or BHKP / LBKP. Either convention.
- Origin or species, if it matters: northern softwood, southern softwood, eucalyptus, birch, mixed hardwood. If you do not state it, you are leaving the choice to the seller.
- Mill, if you have a preference. Pulp is quoted on a named-mill basis, and two mills producing the same nominal grade are not interchangeable to a machine that has been run on one of them.
Add tonnage, destination port and Incoterms, and the offer can come back firm rather than as a question.
The grades we quote, with the Japanese and international names shown side by side, are on the prime pulp page. Off-specification pulp is handled separately — see off grade is not scrap.