Twin Loop - Wire-O and Spiral Binding
Posted: 21st July 2020
Twin Loop or Wire-‘O’ Binding holds the covers and pages of a document firmly in place by a double-loop wire inserted through holes drilled in their left edges. The wire is pre-formed, and open as a 'U' shape, the leaves are threaded over the wire loops and the wire is then compressed to 'close' the wire. The wire can only be closed once and therefore when in place, if changes are required, the wire is taken out and new wire used.
All of the document's pages lay flat when opened, can turn easily through 360°, and stay in perfect registration with adjoining pages. Wire-O bindings are frequently used to bind reference books, reports, proposals, and calendars. For wire bound wall-hung calendars the binding wire is in two pieces either side of a hanger, which has a matching 'thumb cut' cut into the page.
Spiral Binding uses a continuous spiral of wire or plastic that is wound into the article being bound. It is most commonly used for the production of very thick price lists, road atlases, reference manuals and training manuals. One cannot add pages to documents once they are spiral bound, but pages from spiral bound documents cannot come undone from the binding.
The application of spiral binding is more limited than for wire-O binding and therefore is not common