Making Projects Stand Out with Spiral Coil Options

By Rafael Renderos, PEL Manufacturing

Mechanical binding uses many products, including Wire-O, combs and spiral coils (aluminum spirals, wire spirals and plastic spirals). This article focuses on spiral coils, as they are the most popular and most customizable product within the mechanical binding method. Spiral coils come in several diameters, colors, thicknesses, hole spacings and materials.

Spiral coils are measured by inside diameter, with diameters ranging from 3/16″ (4.76 mm) to 4 ½″ (114.3 mm). Currently, the largest diameter in plastic is 3 ½″ (88.9 mm), and 4 ½″ in wire or aluminum. With diameters, gauge (material) thickness comes into play, as each diameter recommends a suggested gauge. But the beauty of spiral coils is there are no “standards.” As mentioned, spiral coils are customizable – it depends on the look one is going for, budget and supplier. For example: a 9/16″ (14.29 mm) 2.5:1 (hole spacing will be covered later) may suggest a gauge thickness of .103, but a gauge thickness of .135 also can be used. Customization can be done with all diameters, hole spacings and materials (aluminum, wire or plastic).

Hole spacing, also known as pitch, refers to the number of holes per inch. For example, a 4:1 pitch means that there are four holes for every inch. There are 10 different pitches available – all serving a purpose – depending on the look one is going for and overall thickness of the project. However, there is no need to worry about having all pitches available – having a couple of them will be enough for most projects. If possible, have a 5:1, 4:1 or 2.5:1. A 5:1 pitch is perfect for calendars, short books/binding edge and thin books/projects. It offers a more appealing look due to the holes being closer together. It is something a project manager may want to suggest to clients, especially when binding short books. A 4:1 pitch can cover a wide range of diameters. It can be used with coil from ¼″ (6.35mm) up to 2″ (50.8mm). This pitch is one to have in inventory. A 2.5:1 pitch is great for larger projects. With a 2.5:1 pitch, a 3 ½″ (88.9 mm) coil can be used. A wider pitch will make the coil easier to insert on thicker projects – something to keep in mind for projects that call for a 2 1/8″ coil or larger.

There currently are three types of materials being used to manufacture spiral coils: plastic, wire and aluminum. In the 1920s, plastic spirals were common. Wire spirals were introduced in the 1980s, and in the 1990s came aluminum spirals.

So, which one is better? This is a question often asked, and it is difficult to give a simple explanation. There are a few components to consider: type of binding project, the look the client is going for and the client’s budget, just to name a few.

Plastic spirals are great for most binding projects, especially children’s books. Plastic spirals come in a variety of colors. About 40 colors readily are available, but custom colors always can be made. Plastic spirals also come in various lengths, ranging from 6″ to 40″, depending on the supplier. Among all three materials, plastic spirals are the most economical so, if the budget is tight, plastic spirals will be the way to go.

Wire spirals, not to be confused with Wire-O, are single-loop spirals, just like plastic and aluminum (yes, the same punching and inserting equipment can be used with all three materials). They also come in a variety of colors, including custom colors. One common complaint is that the material is too thin and the spiral could distort after heavy use. This issue easily can be resolved with a little customization – a heavier gauge can be suggested. For example, many menu companies are using heavy-gauge wire for their projects – .055 gauge with a 7 mm spiral coil. Wire spirals also come in various lengths and pitches.

Aluminum spirals, the newest of the bunch, are becoming popular. Aluminum spirals have been around for almost 25 years but did not gain popularity until the early 2000s, when planner companies started using them. Aluminum spirals also are in high demand with marketing companies, as they always are looking to stand out with a unique product. Many binderies are making a switch from wire to aluminum, as it is a strong alloy but lighter in weight, allowing them to save in shipping costs. The base color for aluminum spirals is silver or “plain aluminum,” but like the other materials, color can be added. Aluminum spirals, made in the USA, are manufactured from “virgin” aluminum and are an eco-friendly product. Like wire and plastic, aluminum spirals also are single-loop continuous coils. Aluminum spirals also offer a wide range of diameters, from 3/16″ (4.76 mm) to 3 ½″ (88.9 mm), and they can be manufactured in 10 different pitches.

Mechanical binding offers a wide range of products, not just plastic spirals, and within each of the materials used there are options. Each binding project is different – each customer is different – and it is up to binders and finishers to make customers aware of all available mechanical binding options.

Rafael Renderos is a sales and marketing specialist at PEL Manufacturing. Learn more at