What 100gsm actually means, and why it is worth paying for
Paper weight is the least glamorous specification on the page and the one that decides whether you use the whole notebook.
GSM is grams per square metre: the weight of a single sheet one metre on each side. It is a measure of mass, not thickness, but for the uncoated paper notebooks are made from the two track each other closely enough that gsm is the number worth reading.
What the numbers feel like
| 70-80gsm | Office printer paper. What most notebooks use. |
|---|---|
| 90gsm | Noticeably sturdier. Safe for gel pen and most fountain nibs. Our journals. |
| 100gsm | Holds a broad fountain nib and highlighter. Our planners. |
| 120gsm+ | Sketchbook territory. Heavy to carry a year of. |
Bleed-through and ghosting are different problems
Bleed-through is ink physically passing through the sheet and appearing as a wet mark on the back. It ruins the reverse side. Ghosting is only seeing the shadow of what is on the other side; the reverse is still perfectly writable.
Some ghosting is normal on any paper light enough to carry around, and it is not a defect. Bleed-through is the one that costs you half the book, because nobody writes on a page with wet marks coming through it. 100gsm is roughly where bleed-through stops for the pens most people use.
What bleeds on what
| Ballpoint | Fine on anything from 70gsm up |
|---|---|
| Gel pen | Usually fine from 80gsm, can bleed at 70 |
| Fountain pen, fine nib | Wants 90gsm or more |
| Fountain pen, broad or wet | Wants 100gsm |
| Highlighter | Wants 100gsm — the usual culprit |
The cost, honestly
Heavier paper costs more per sheet and weighs more to post, and both end up in the price. A 200-page book at 100gsm is meaningfully heavier than the same book at 80. That is a real trade and we have made it deliberately in one direction, because a notebook you stop using halfway through was not cheaper, it was wasted.
How to check a book you already own
- Hold a page to the light. If you can read the text on the other side rather than just sense it, the stock is light.
- Draw a highlighter line and turn the page over. A shadow is ghosting and is fine; a wet-looking mark is bleed-through.
- Feel the edge of the block. Heavier stock has a distinct stiffness when you riffle it.