Index Stock, Mylar and Die-Cutting: What They Actually Are

Index stock is a stiff, uncoated paper made to be handled rather than read. It takes ink well, it does not curl in a binder, and it holds a cut edge — which is what a tab is.

The confusion is the number. US paper weight is the weight of 500 sheets at that grade's own basis size, and every grade uses a different basis size. So 90 lb index and 90 lb text are not the same thickness, and 20 lb bond copy paper is not one quarter of 90 lb index. Compared like for like: 90 lb index is roughly 163 gsm and 110 lb index roughly 199 gsm, where 20 lb bond is about 75 gsm. That is why a tab printed on copy paper folds over inside a week — it is less than half the substance.

Tabzoola prints paper tab dividers on 90 lb or 110 lb white index stock. 90 lb is the production standard for tab dividers and 110 lb is chosen when a set will be handled daily for years.

• 90 lb index ≈ 163 gsm — the standard for tab dividers
• 110 lb index ≈ 199 gsm — stiffer, for heavy daily handling
• 20 lb bond (copy paper) ≈ 75 gsm — not a tab stock
• Weights are not comparable across grades; gsm is the only fair comparison

Mylar is a polyester film applied over the tab so the extension survives being pulled. It is often called laminating, which is misleading: a laminate encases a whole sheet in plastic, while tab Mylar is a narrow strip bonded along the tab only, leaving the rest of the sheet as plain paper that still takes a pen.

The order of operations is the part people get wrong, and it is the reason this cannot be done at home. The sheet is printed on a press; the Mylar is then applied and the tab cut in a single second operation. The film goes on BEFORE the tab is cut, so the cut passes through paper and film together and the edge seals as it is made. Adding film to an already-cut tab leaves an unsealed edge that peels.

Mylar also carries colour. Tabzoola offers 19 Mylar colors, and because the colour sits on the tab it is what identifies a section from the edge of a closed binder. It comes on paper tabs only — solid poly dividers are already tear-proof and are never Mylar-reinforced.

• A strip on the tab, not a coating on the sheet
• Applied before the cut, in the same operation — that is why it seals
• 19 colors; the colour is what you see from the edge of a closed binder
• Paper only. Poly is never Mylar-reinforced

A die is a shaped steel rule mounted in a press that cuts a specific profile in one stroke. A guillotine or a printer's trimmer can only make straight cuts across a whole sheet, which is why neither can produce a tab: a tab is a shape that stops partway along an edge, with square shoulders and a specific length.

One stroke also means every sheet is identical. Hand-trimming twenty sets produces twenty slightly different tabs; a die produces the same tab until the steel wears. That repeatability is most of what you are buying when a set has to look the same across a hundred binders.

Anselmo Die & Index is named for the die: the company cuts its own tab dies, which is why cuts from 1/2 through 1/15 are all standard here rather than a special order, and why a set can be matched to an existing book from a sample.

• Shaped steel rule, one stroke, one profile
• A trimmer cuts straight lines across a sheet — it cannot make a tab
• Every sheet identical, which is what consistency across binders means
• Cuts 1/2 to 1/15 are all standard, not special orders