Floating eyewear is one of those categories where the marketing runs well ahead of the engineering. A pair either floats or it does not, and whether it does comes down to one measurable property: the density of the frame material relative to water.
What floats: frames moulded in TPX (polymethylpentene), a low-density olefin copolymer
Why it floats: TPX density is below 1.0 g/cm³, the density of water
What does not: TR90, polycarbonate and nylon frames sink, whatever the coating
Minimum order: 300 pieces per floating model
1. What TPX actually is
TPX™ is a 4-methylpentene-1-based olefin copolymer. It is a crystalline olefin polymer that nonetheless transmits light, which is unusual for that family — most crystalline polyolefins are opaque. Mitsui Chemicals, which owns the TPX trademark, lists its defining characteristics as heat resistance, release properties, chemical resistance and low weight.1
That combination is why it turns up in laboratory ware, food packaging and medical components as well as in eyewear. It is not a material invented for sunglasses; it is an industrial polymer that happens to be unusually light.
2. Why a TPX frame floats
An object floats when its overall density is lower than the density of the liquid it sits in. Fresh water is 1.0 g/cm³; seawater is slightly higher, around 1.025 g/cm³. TPX sits below both.
The exact figure depends on the grade — TPX is supplied in several grades with different flow and impact characteristics — so we do not quote a single number here. The relevant point for a buyer is the relationship, not the decimal: the frame material is less dense than the water, so the frame rises. A frame moulded from TR90 or polycarbonate is denser than water and sinks, regardless of how the lens is coated or how the temples are finished.
Two practical consequences follow:
- A floating frame can still sink if enough metal is added to it. Hinge screws are unavoidable, but metal inlays, heavy decoration and metal-moulded nose bridges add mass. This is why the material specification and the hardware specification have to be considered together.
- A floating frame floats. It does not hover, and it does not resist being pushed under. It returns to the surface when released.
3. Where TPX sits against TR90 and polycarbonate
| Property | TPX | TR90 | Polycarbonate |
|---|---|---|---|
| Density relative to water | Below — floats | Above — sinks | Above — sinks |
| Transparency | Transparent | Transparent | Transparent |
| Chemical resistance | High1 | Moderate | Moderate |
| Heat resistance | High1 | Moderate | Moderate |
| Typical use in eyewear | Floating frames | Sport and lifestyle frames | Shield lenses, sports frames |
Density is the property that decides the category. The others decide how the frame behaves once it is in service.
4. Which frame shapes can be made in TPX
This is where the specification gets narrower.
Supplier process specification
Full-rim frames only. Half-rim and rimless constructions cannot be produced in floating material. The frame relies on a continuous rim for structural integrity in this material; remove the lower rim and the construction does not hold.
Metal structures are excluded. Frames with metal components — and metal-framed categories generally — are not available in floating material.
Some ranges are excluded outright. Cycling eyewear and certain sport series are not produced in TPX, for the same structural reasons.
The consequence for a buyer is straightforward: if the design you want is a half-rim or a rimless shield, floating is not an option at any quantity. If it is a full-rim wrap or a full-rim square, it can usually be built.
5. Frame colour: what is realistic
Colour in TPX is more constrained than in TR90 or polycarbonate, and it is worth being precise about why rather than simply listing what is available.
The material is processed at high temperature and has a low melt viscosity compared with the styrenic and polyamide materials used for conventional frames. Pigments and effect additives that disperse cleanly in TR90 do not always disperse evenly in TPX, and some effect pigments — the ones that produce the deep amber, tortoise and metallic flake finishes — are the hardest to stabilise.
Supplier process specification
In practice, standard production colours for floating frames are black and grey, in matte and transparent finishes. Other colours can be discussed, but they should be treated as a development question rather than a catalogue choice: feasibility, minimum quantity and lead time all need to be confirmed against the specific colour before it is quoted.
If a specific frame colour is essential to your range, the sensible sequence is to settle the colour question before the frame is specified, not after. On conventional materials the colour range is far wider.
6. Where floating frames earn their cost
- Shore and boat fishing. Dropping a pair over the side is the single most common way anglers lose sunglasses. A frame that returns to the surface is recoverable.
- Kayaking, paddleboarding and open-water swimming. Same logic, higher consequence.
- Any water-adjacent activity where the wearer cannot retrieve a dropped item.
It is worth being honest about the limits. Floating material solves one problem. It does not make a frame more impact resistant than polycarbonate, it does not improve optical clarity, and it does not replace a retaining strap — a strap keeps the glasses on your head, which is a different failure mode from losing them in the water. The two are complementary, not alternatives.
7. Common questions from buyers
Does the lens have to be polarised?
No, but in practice floating frames are almost always built with polarised lenses because the two features serve the same customer. Our floating range uses polarised TAC lenses.
What is the minimum order?
300 pieces per floating model. The minimum is per model, not per order, so a mixed order of three floating models starts at 900 pieces rather than 300.
Can I have my logo on a floating frame?
Yes. The logo is applied to the frame after moulding, so the material does not restrict it. Standard single-colour silk-screen is the usual choice.
Can an existing frame in your range be converted to floating material?
Sometimes. The frame has to be full-rim and free of metal structure, which rules out a significant part of any catalogue. Where a frame qualifies, the conversion is a tooling and material change rather than a cosmetic one, and it is quoted case by case.
Does salt water damage the frame?
TPX has good chemical resistance, so the frame itself tolerates salt water. The lens coating is the part that needs attention in a saltwater environment, which is why an anti-saltwater coating is available as an option and is generally worth specifying for sea fishing.
8. Sources
- Mitsui Chemicals — TPX™ (Polymethylpentene) product page. Material definition and stated characteristics (heat resistance, release properties, chemical resistance, low weight). jp.mitsuichemicals.com
Structural and colour statements in sections 4 and 5 are supplier process specifications rather than published material data, and are marked as such. They reflect current production capability and are confirmed per order. Density figures for TPX vary by grade; consult the material supplier’s technical data sheet for the specific grade in use.
WORLUX SPORTS supplies floating eyewear in TPX from 300 pieces per model. Download the floating catalogue or request a quotation.