Resistance band ranges are almost always sold as a ladder of levels, and every buyer inherits the logic the supplier used to build that ladder. Two suppliers can both list five levels and still deliver very different force at the same colour. A level system becomes procurable only when it is anchored in measurable geometry and a stated elongation, so that factory, buyer and retail partner all read the same number.
Defining a level by thickness and width, not by feel
Feel is not a specification. Two people squeezing the same band will rate it differently, and a band stored cold reads firmer than the same band at room temperature. A durable definition starts with the two dimensions anyone can measure with a caliper and a tape: wall thickness and cut width for a flat strip, wall thickness and tube width for a closed loop. Because resistance scales with cross sectional area, a ladder can be built by changing one variable at a time, width first and thickness second, and then recording the pair as the level definition. That produces a table the factory can cut to and the buyer can audit on arrival. Elongation completes the definition, because a level means nothing unless force is quoted at a fixed stretch, such as at one hundred or two hundred per cent elongation. When a supplier describes the compound rather than the finished band, the recognised reference for tensile behaviour is ASTM D412, the tension test method for vulcanised rubber and thermoplastic elastomers, and asking for results in that language keeps the conversation technical.
Colour coding conventions and where they collide
Colour is a label, not a measurement. The common convention moves from pale yellow or tan through red, blue and green to black as resistance increases, but that sequence is a habit rather than a standard, so the same five colours can describe a light rehabilitation range in one catalogue and a heavy strength range in another. Collisions appear in three places: two ladders from different origins placed side by side in one studio, a brand keeping its own palette while sourcing from several factories, and markets where red is read as a warning rather than as a level. Colour vision deficiency adds a fourth problem, since red and green pairs are the most frequently confused. The safeguards are simple. Give every level a number as well as a colour, print the number on the band and on the polybag, and publish the level table as part of the product data so a replacement order can be checked against a number instead of a shade.
Equating loop bands with flat strips
A closed loop and a flat strip are sold as if colours carried across, but the geometry does not match. A loop presents two legs of material to the load, so its resistance at a given stretch is roughly double that of a single strip of the same wall thickness and width, before any allowance for the shorter free length and the pre tension built in when the loop is anchored at a fixed distance. Converting between the two therefore needs three facts: the cross section of one leg, the free length at which force is quoted, and the elongation at that length. With them, a force per unit of cross section can be calculated for each product and levels mapped one to another. Without them a colour chart is only a marketing device. Suppliers publishing both formats should state the reference length for each, and buyers comparing quotations should confirm that quoted force refers to the same elongation and the same free length, otherwise a lighter loop will appear stronger than a heavier strip.
What belongs on the band, and how buyers verify it
Marking has a content boundary. A band body can reasonably carry the level number or name, the nominal width and thickness, the compound family, the nominal force at a stated elongation, a lot reference and the brand. It should not carry a full specification, a certification claim the supplier does not hold, or a force figure quoted at an elongation the buyer cannot reproduce. Everything else belongs on the polybag, the carton label or the product data page. Verification at goods inwards is then a routine rather than a debate:
- Measure width and wall thickness with a caliper at three points along the band and record the range.
- Hang a known mass from a fixed free length and measure the stretched length to check the quoted force at that elongation.
- Compare the colour and number on the band against the published level table, never against a band from another supplier.
- Check the lot reference against the first article sample approved for that level.
Language adds one more layer. Colour names translate badly: natural usually means translucent and additive free rather than a beige shade, and in some markets red is the lightest level while in others it is the heaviest. A neutral numbering system on the band, with colour as a secondary cue on packaging, keeps a multilingual range consistent in studios where staff read different languages. Buyers building a private label ladder can define their own geometry and numbering with the factory through the custom programme, and should have the level table and marking layout approved in writing before the first production run.
None of this is complicated, but it has to be decided before the first order rather than after the first complaint. A documented ladder, a colour table with numbers, a stated elongation behind every force figure and a marking layout that actually fits on the band are the four documents that make a range workable across borders. To review an existing range against this framework, the production background described on the about page shows how such specifications are applied in practice, and the contact page is where a current level chart can be sent for comparison.
Frequently asked questions
Should the level be defined by colour or by a number?
By geometry and by number, with colour as a secondary cue. A number survives a change of factory, a change of palette and a buyer who reads a different language. Colour alone does not survive any of those.
Can a loop band and a flat strip share one level table?
They can, but only if the table states the free length and the elongation behind each force figure. A loop carries two legs and a shorter free length, so its force at the same stretch is much higher than a strip of identical wall thickness and width.
What is the minimum marking for a private label band?
Level number or name, nominal width and thickness, compound family, force at a stated elongation, lot reference and brand. The full specification belongs on the packaging and the product data page.