How to stop helmet visor fogging, in one paragraph: a visor fogs when warm, moist air from your breath meets a cold visor and condenses on the inside. You stop it by keeping that inner surface warmer than the dew point of the air touching it, and by cutting how much breath reaches it. In practice that means a pin-style anti-fog insert first, then correct ventilation, then breath management. Sprays and home remedies are a distant fourth, and several of the popular ones damage a visor permanently.
That is the whole mechanism in one paragraph. The rest of this guide explains why each fix works, when it stops working, what to do at a wet set of traffic lights in February, and how to pick a visor that suits the riding you actually do. It is written for UK riding conditions, where the problem is cold rain rather than dry cold, and where the law about visor tints is widely misunderstood.
What this guide covers
- Why a visor fogs, in plain physics
- How to stop helmet visor fogging at the roadside
- Anti-fog inserts: the durable fix
- Fitting and tensioning an insert properly
- Factory anti-fog coatings and how they fail
- Sprays, treatments and the home remedies that ruin visors
- Using your helmet’s ventilation properly
- Breath guards, chin curtains and breathing technique
- Riding in glasses without fogging both lenses
- Cold, rain and the British winter
- Cleaning a visor without destroying the coating
- Choosing a visor: clear, photochromic or tinted
- Finding a visor that fits your helmet
- The legal position in the UK
- Nine mistakes that keep riders fogging
- Frequently asked questions
Why a visor fogs, in plain physics
Condensation is not a helmet fault or a visor fault. It is what air does when it cools past the point at which it can hold the water vapour it is carrying. Warm air holds more water vapour than cold air, and air leaving your lungs is close to body temperature and effectively saturated.
When that air reaches a visor chilled by the airflow of a cold morning, it cools almost instantly and drops below its dew point. The water it can no longer carry as vapour appears on the nearest cold surface as a film of very fine droplets. Those droplets scatter light, and scattered light is what you perceive as fog.
Three variables drive the whole problem, and every genuine fix moves at least one of them.
- The temperature of the inner visor surface. The colder it is relative to the air inside the helmet, the sooner condensation starts. This is the variable an anti-fog insert attacks.
- The amount of moisture in the helmet. More breath in the shell means a higher dew point, so fogging begins at a warmer visor temperature. This is what ventilation and breath deflection attack.
- The surface itself. A surface that encourages water to sheet out into an even film rather than bead into droplets still gets wet, but stays optically clear. This is what anti-fog coatings and treatments attack.
That third point is worth sitting with, because it explains why a treated visor can feel damp to the touch and still be perfectly clear. Anti-fog technology almost never keeps water off the plastic; it changes the shape water takes on it. Droplets have curved surfaces that refract light in every direction, while a continuous film has a flat surface that light passes through cleanly. The water is still there either way.
Why a well-sealed helmet can fog more, not less
The mechanism also explains the most common misunderstanding riders have about fogging: that it happens because the helmet is badly sealed. The opposite is usually closer to the truth. A helmet that seals tightly around your chin traps exhaled air where it can reach the visor.
A helmet that allows a small, controlled flow of outside air across the inner face of the visor keeps that surface swept and dry. Sealing is good for noise and for weather. It is not, on its own, good for fogging.
Why it is worst when you stop
At road speed, air moving through the helmet’s intakes does two useful things: it carries moist air out of the shell, and it slightly warms the inner visor surface by mixing. Stop at a junction and both effects vanish at once. The airflow stops, your breathing rate often stays elevated, and the visor surface keeps radiating heat away.
Riders frequently describe a visor that is clear at speed and fogs solid within seconds of stopping. That is not a defective visor. That is the physics doing exactly what it must.
How to stop helmet visor fogging right now, at the roadside
If you are reading this on a phone with a fogged visor in front of you, here is the order that works, quickest first. None of it is a substitute for a proper fix, and all of it is safer than riding with degraded vision.
- Crack the visor to the first detent. Almost every modern visor has a first position that opens a few millimetres. That gap lets moist air escape and pulls drier outside air across the inner surface. At town speeds it usually clears a visor within seconds.
- Open every intake you have. Chin vent first, then brow and top vents. The chin vent is the one that directs air onto the back of the visor, and it is the one riders most often leave shut all winter.
- Change how you breathe. Breathe out downwards, through the chin bar rather than straight ahead. It feels awkward for the first mile and becomes automatic quickly.
- Get moving if it is safe to do so. Airflow is the fastest dehumidifier you have.
- Do not wipe the inside with a glove. A wet glove smears road film across the surface, and the textile or leather will scratch a soft anti-fog layer. If you must clear it by hand, use a clean microfibre and a light touch.
If you find yourself doing this several times per journey, the helmet is telling you something. Persistent fogging in mild conditions usually means either that there is no anti-fog insert fitted, or that an insert is fitted badly, or that the visor’s original coating has been cleaned off. Each of those has a real fix, and they are covered below.
Anti-fog inserts: the durable fix
An anti-fog insert is a second, thinner lens that clips to the inside of the main visor and seals to it with a silicone bead around its edge. Between the insert and the visor sits a sealed pocket of air. That trapped air is a poor conductor of heat, so it insulates: the inner face of the insert stays much closer to the temperature of the air inside your helmet than the visor itself does, and if it never falls below the dew point, condensation never forms on it.
This is double glazing, applied to a helmet, and it works for exactly the same reason double glazing works. It is worth being precise about why it outperforms everything else. A coating or a spray alters the surface so that condensation is optically harmless; an insert stops the condensation forming at all.
The first is a mitigation and degrades as the treatment wears. The second is a change to the thermal behaviour of the visor, and it does not wear in the same way. In sustained cold and wet, the conditions that defeat sprays within minutes, a correctly fitted insert simply keeps working.
Inserts are held in place by two pins mounted through the visor, which is why they are commonly called pin-style or pin-lock inserts. Pinlock® is a third-party brand name and a registered trademark of its owner; we use it here only to describe the pin fitment system that a visor may be drilled for, and we sell compatible aftermarket inserts rather than that company’s products. If your visor has two small pins or two small holes near the lower edge on each side, it takes a pin-style insert.
Inserts are commonly sold in different clarity grades, usually described by a number. The number refers to how much light the insert lets through, and it is a genuine trade-off rather than marketing. A higher-clarity insert transmits more light and is better for night riding and dark winter mornings.
A lower-clarity insert typically carries a more aggressive moisture-absorbing layer and resists fogging harder in extreme damp, at the cost of some light. Most UK riders doing a mix of commuting and weekend miles are best served by the highest-clarity option they can fit. The British problem is usually darkness and drizzle rather than sub-zero endurance riding.
We have written a dedicated comparison of the two grades riders ask about most: see our breakdown of the 70 and 120 clarity grades. For the full range of pin-style inserts and how to tell which one your helmet takes, start at our anti-fog inserts hub.
Fitting and tensioning an insert properly
A badly fitted insert fogs, and it fogs in a way that convinces riders the product does not work. Almost every complaint about inserts traces back to one of three fitting errors, and all three take a minute to correct.
Insufficient tension. The pins are eccentric, meaning they rotate off-centre, so turning them changes the distance between them and therefore how hard the insert is pressed into the visor. If the silicone bead is not compressed evenly all the way around, the air pocket is not sealed, moist air reaches the gap, and you get condensation between the two lenses.
That is the classic symptom: fog you cannot wipe off, because it is on a surface you cannot reach. The fix is to remove the insert, rotate both pins a small equal amount to widen the spacing, and refit.
Fitting it cold, or fitting it dirty. The silicone seal beds in better at room temperature, and any dust trapped on the bead becomes a leak path. Fit inserts indoors, on a visor that has been cleaned and fully dried, handling the insert by its edges.
Leaving the protective film on. Inserts ship with a peel-off film on one or both faces. Riders regularly fit them with the inner film still attached, then report that the anti-fog side does not work — which is true, because the moisture-absorbing surface is still under plastic. Check both faces before fitting.
Once fitted, treat the insert as the delicate component it is. The anti-fog face is a soft absorbent layer, not hard-coated like the outside of your visor. Never wipe it dry and never use solvent on it. If it needs cleaning, rinse with clean lukewarm water and let it air-dry, because a single pass with a dry cloth can leave permanent marks directly in your line of sight.
If your visor has no pins, you are not stuck. Many helmets can take a pin-drilled replacement visor, and for a large number of models we stock exactly that. Browse by helmet brand from the full visor range, or jump to your make in the fitment section below.
Factory anti-fog coatings and how they fail
Many visors leave the factory with an anti-fog treatment applied to the inner surface. These coatings are usually hydrophilic: rather than repelling water, they encourage it to spread into an even, optically clear film. Some also incorporate an absorbent layer that takes up a quantity of moisture before any film forms at all.
They work well when new. They fail in three predictable ways, and understanding which one you are experiencing tells you whether the visor is recoverable.
Saturation. An absorbent coating has a finite capacity, and on a long wet ride it fills, behaving like untreated plastic once full. This is reversible: the coating dries out and recovers. If your visor is fine for the first half hour of a wet commute and then fogs steadily, this is what is happening, and an insert is the answer because it removes the load rather than absorbing it.
Abrasion. Anti-fog coatings are soft, so wiping a dry, gritty visor with a sleeve, a glove or a paper towel removes the coating in exactly the area you look through. This is not reversible. The visor is still structurally sound and optically fine; it has simply lost its anti-fog property and needs an insert or replacement.
Chemical damage. Solvents, alcohol-based cleaners, screen wash, petrol splash and some household glass cleaners attack both anti-fog coatings and the polycarbonate underneath, and ammonia-based cleaners are the classic offender. Damage here can go beyond the coating into the visor itself, producing fine crazing that catches oncoming headlights. That visor should be replaced, and you can find a direct replacement for most helmets through our visor finder.
The practical conclusion is that a factory anti-fog coating is a consumable. Treat it gently and it will serve for a long time; treat it like a windscreen and it will be gone in a season. Nothing you can buy will restore a removed coating to its original condition, which is why riders who do serious winter mileage tend to move to inserts and stop worrying about the coating at all.
Sprays, treatments and the home remedies that ruin visors
Anti-fog sprays and gels are surfactant-based. They lower the surface tension of water so it cannot bead, spreading it into a film instead. Applied to a clean visor and buffed correctly, a good one genuinely works.
It has two limitations that matter on the road: it wears off, and it has a saturation point in heavy damp beyond which it stops helping. For a dry cold morning commute a spray may be all you need. For a four-hour ride in November rain it will not last the journey.
If you use one, three rules make the difference between a clear visor and a smeared one. Apply it to a genuinely clean, dry surface, because a surfactant over road film just spreads the film. Use very little, since excess product is the usual cause of the greasy halo riders notice against oncoming headlights. Never apply spray to the anti-fog face of an insert, which is already an absorbent layer and will be permanently marked by it.
Now the home remedies, because they circulate endlessly and several of them cause real damage to a safety-critical component.
- Washing-up liquid. The one home remedy with a defensible mechanism — it is a surfactant, and a very dilute smear buffed almost dry does reduce beading. It is also easy to overdo, and residue refracts light badly at night. Use a purpose-made product instead.
- Shaving foam. Widely repeated, and it does leave a surfactant film. It also frequently contains additives that mark polycarbonate, and the amount of buffing needed to clear the residue is exactly the dry abrasion that destroys an anti-fog coating.
- Toothpaste. Avoid entirely. Toothpaste is a mild abrasive. It is designed to polish enamel, and on a visor it produces a haze of fine scratches that you will see every time a car approaches at night.
- Potato, saliva, and similar. No durable mechanism, and both leave organic residue that goes cloudy and smells.
- Water repellents intended for car glass. These are hydrophobic — the opposite of what the inner surface needs — and many are solvent-carried. They belong on the outside of a visor at most, and even then check the formulation is safe for polycarbonate.
The pattern is consistent: anything abrasive, anything solvent-based, and anything you have to rub hard to remove will cost you more in optical clarity than it gains you in fog resistance. Your visor is the only thing between your eyes and the road, and it is the cheapest part of your helmet to replace when it is past its best.
Using your helmet’s ventilation properly
Helmet ventilation is designed as a system with a defined path: air enters at the chin and brow, flows through channels in the liner, and exits at the rear. Riders routinely defeat that system without realising, usually by closing the chin vent in winter because cold air on the face is unpleasant.
The chin vent is the one that matters for fogging. It is positioned to direct incoming air up the inner face of the visor, sweeping the exact surface where condensation forms. Closing it in cold weather is understandable and is also the single most common self-inflicted cause of a fogged visor. If cold air on your face is the problem, a breath guard is the correct answer, not a closed chin vent.
Rear exhaust vents matter more than riders assume. Air only flows in if it can flow out. A helmet with intakes open and exhausts blocked — by a closed slider, by a hood, by a rucksack sitting high on the shoulders — does not ventilate. If you have opened everything at the front and nothing has changed, check the back.
Three habits are worth building. Open the chin vent before you set off in cold or wet weather, rather than after the visor has already fogged, because clearing an established fog takes far longer than preventing one. Use the visor’s first detent as a deliberate tool in slow traffic rather than an emergency measure.
Then check your vents are actually operating. Sliders seize with road salt and grit, and a vent that feels closed because the mechanism has jammed open is just as misleading as one you forgot to open.
Breath guards, chin curtains and breathing technique
Everything above manages moisture after it has entered the helmet. Breath management stops it arriving. It is the cheapest improvement available and the one riders most often skip.
A breath guard is a moulded deflector that sits over the nose inside the chin bar and redirects exhaled air downwards and out of the chin vent instead of upwards onto the visor. Many helmets ship with one in the box. A great many of those end up in a drawer within a week because they feel odd at first. If yours is in a drawer, retrieve it before spending money on anything else in this guide.
A chin curtain is a fabric skirt that closes the gap under the chin bar. Its main job is reducing wind noise and cold draughts, and its effect on fogging is genuinely mixed. It reduces the cold airflow that chills the visor, which helps, but it also reduces the escape route for moist air, which hurts.
In practice most riders find a chin curtain helps in cold dry conditions and hurts in mild wet ones. It is removable on most helmets, so it is worth trying both ways rather than assuming.
Technique is free. Consciously breathing out downwards, and slowing your breathing at a standstill, makes a measurable difference to how quickly a visor fogs at lights. Riders who have come from cold-weather sport tend to do this already. Anyone who has ever fogged a pair of ski goggles has learned the same lesson.
One combination is worth calling out because it defeats almost everything else: a neck tube or buff pulled up over the nose. It funnels a continuous stream of warm, saturated air straight up behind the visor. If you ride in a buff and fog constantly, pull it below your chin and the problem frequently disappears on its own.
Riding in glasses without fogging both lenses
Riders in prescription glasses have two surfaces to keep clear, and the lens sits in the worst possible place: close to the face, poorly ventilated, and shielded from the airflow that would otherwise sweep it. Solving the visor without solving the glasses just moves the fog a centimetre closer to your eye.
The measures that help most are unglamorous. Get the airflow path right first, because a helmet whose chin vent is open and whose exhaust is clear will clear glasses too. Fit a breath guard, since deflected breath is breath that never reaches your lenses.
Use an anti-fog treatment made for optical lenses rather than one made for visors, and follow its instructions, because many spectacle lenses carry coatings that are damaged by the wrong product. If you wear a buff, keep it off your nose.
Helmet choice matters more for glasses wearers than for anyone else. Helmets with channels moulded into the cheek pads for spectacle arms let the glasses sit properly rather than being pushed askew, and a helmet that fits correctly with glasses on is one where the lenses sit further from the face and in better airflow. If you are choosing a new helmet and you ride in glasses, try it with your own frames on.
Finally, consider whether you need the glasses under the helmet at all. Some riders find a photochromic visor removes the need for prescription sunglasses over contact lenses, which takes one fogging surface out of the system entirely. Our photochromic visor range covers most popular helmets.
Cold, rain and the British winter
The UK produces a specific and unhelpful combination: temperatures a few degrees above freezing, high relative humidity, and persistent light rain. Dry cold is comparatively easy, because cold dry air entering the helmet carries little moisture and dries the shell as it passes through. Mild damp is much harder, because incoming air is already close to saturation and has almost no capacity to absorb what you exhale.
Rain compounds it from the outside as well. Water on the outer surface of a visor cools it by evaporation, dropping the inner surface temperature further below the dew point of the air inside. This is why a visor that is well behaved on a cold dry morning fogs stubbornly in mild drizzle, and why riders often conclude their anti-fog measures have failed when conditions have simply got harder.
Wet gear inside the helmet is the underrated factor. A soaked collar, a wet buff or damp hair puts a continuous source of evaporating water directly into the airflow. On multi-day trips, drying the helmet liner fully between rides makes a noticeable difference. Dry it at room temperature and never on a radiator, which distorts the shell’s internal components.
Winter also brings the light problem. Dark mornings and dark evenings mean the visor you ride behind should be as clear as possible, which is a good reason to prioritise a high-clarity insert and to keep a spare clear visor available. Riders who run a tinted visor through summer often forget to swap back until the first genuinely dark commute catches them out. Our clear visor range exists largely for that swap.
Cleaning a visor without destroying the coating
More anti-fog performance is lost to bad cleaning than to age. The method below is slow, and that is the point.
- Remove the visor from the helmet where the mechanism allows. It lets you support the visor properly and keeps water out of the liner.
- Take the insert out and set it aside. It is cleaned separately, with water only.
- Soak, do not scrub. Lay a cloth soaked in lukewarm water over the visor for several minutes. Insects and road film need to be softened off, never abraded off. This single step prevents most scratching.
- Rinse under running lukewarm water to float away the loosened debris before anything touches the surface.
- Use a clean microfibre and no pressure, in straight passes rather than circles. Circular motions concentrate any grit into arcs that sit right in your field of view.
- Air-dry, or blot. Do not polish it dry.
Avoid, without exception: ammonia-based glass cleaners, alcohol wipes, solvents, screen wash, abrasive pastes, paper towel and kitchen roll. Paper products are wood fibre and are more abrasive than they feel. Keep a dedicated visor microfibre and wash it separately from cloths that have touched chain lube or polish, because one contaminated cloth will scratch every visor it touches thereafter.
If you would like this in more depth, including which products are safe on both a visor and an insert, we have a fuller treatment in our guide to anti-fog for helmet visors.
Choosing a visor: clear, photochromic or tinted
Fogging behaviour is not the only reason to choose one visor over another, but it interacts with the choice more than riders expect. A visor you have to lift constantly because it is too dark for the conditions is a visor that fogs, because lifting it lets warm moist air flood the inside.
| Visor type | Best for | Night and low light | Takes a pin-style insert | UK road use |
|---|---|---|---|---|
| Clear | Commuting, winter, night, all-weather | Ideal | Commonly, model dependent | Suitable |
| Photochromic | Riders who meet changing light on one journey | Clears as light falls | Commonly, model dependent | Suitable |
| Light tint | Bright summer daytime riding | Not suitable | Model dependent | Depends on the marking on the individual visor |
| Dark tint | Track and off-road use | Not suitable | Model dependent | Not road legal in the UK |
| Iridium or mirrored | Track and off-road use | Not suitable | Model dependent | Not road legal in the UK |
A photochromic visor darkens in ultraviolet light and clears as it falls, which suits UK riding well: you leave in gloom, ride into brightness, and come home in gloom again, without carrying a spare visor or stopping to swap. Two practical caveats are worth knowing before buying. The reaction is driven by UV rather than visible brightness, so behind a car windscreen the effect is reduced, and the transition is not instantaneous, so going into a long tunnel the visor takes time to clear. You can see the range at our photochromic visors page.
A clear visor remains the correct default for anyone whose riding includes darkness, and it is the one to prioritise for insert clarity. Browse clear replacement visors.
Iridium and mirrored finishes look excellent and are the most commonly misunderstood category on the market. They transmit too little light to be legal for road use in the UK, and that is true in daylight as well as at night. We stock them for track and off-road use and label them accordingly; see our iridium visor range and the detail in the legal section below.
Finding a visor that fits your helmet
Visors are not interchangeable between helmet families, and the same manufacturer often uses several different mechanisms across its range. Fitment is determined by the model of helmet, and sometimes by the production year, rather than by the brand alone. A visor for one AGV model will frequently not fit another.
The reliable method is to identify your exact helmet model — it is usually printed on a label inside the shell or moulded into the visor mechanism — and then match to that model. Our visor finder is built for that, and every product page lists the helmet models the part is compatible with.
To browse directly by helmet make:
- Visors and inserts that fit AGV helmets, including the K1, K3, K6 and Pista families
- Visors and inserts that fit Shoei helmets
- Visors and inserts that fit HJC helmets
- Visors and inserts that fit Arai helmets
- Visors and inserts that fit LS2 helmets
- Visors and inserts that fit Shark helmets
- Visors and inserts that fit Scorpion helmets
- Visors and inserts that fit MT helmets
- Visors and inserts that fit Bell helmets
As worked examples, riders arrive at anti-fog inserts most often for a handful of popular models: there are compatible inserts for the AGV K6, for the AGV K3, for the HJC C10 and for the Arai Tour-X5. If your helmet is not among them, the brand pages above will have it or the finder will.
One caution on measurements: do not buy a visor by comparing photographs. Mechanisms that look identical often differ in the position of a single lug. Match the model name, and where a product page lists a year range, check yours falls inside it.
The legal position in the UK
This section matters because the rules are widely misreported, including by retailers. Nothing here is legal advice, and the responsibility for what is fitted to a helmet on the road sits with the rider.
The legal test is the marking on the individual visor, not its colour and not its name. For road use in Great Britain an eye protector is expected to carry either a BS 4110 grade with an approved certification mark, or an ECE 22.05 approval, applied to that specific visor. A visor with no such marking is not made road legal by being clear, and a visor is not made illegal simply by being described as tinted. Look for the mark.
BS 4110 is the visor standard. BS 6658 is a helmet standard. The two are routinely confused, including in articles that otherwise get the law right. A product listing that cites BS 6658 for an eye protector is quoting a helmet standard, and it tells you nothing at all about the eye protector in front of you.
Iridium, mirrored and dark-smoke visors are essentially never legal for UK road use. They transmit too little light to be legal for road use, and this holds in daylight as much as at night. The frequently repeated idea that a mirrored visor is acceptable during the day has no basis in the regulations. We sell these finishes for track and off-road use.
The commonly quoted 50% light-transmission figure derives from ECE Regulation 22, the international standard for helmets and visors. It is a requirement inside that regulation rather than a separate piece of UK legislation. Descriptions presenting it as an independent statute are reporting the regulation second-hand.
Selling an eye protector as authorised for road use when it is not a prescribed type is an offence for the seller under section 18(4) of the Road Traffic Act 1988, carrying a fine at level 3 on the standard scale, to a maximum of £1,000. It is non-endorsable: there are no penalty points attached to it. Claims that a tinted visor carries three points are false. The types prescribed for road use are set out in the Motor Cycles (Eye Protectors) Regulations 1999.
One closing point. We do not verify the markings on individual items in our range, so we do not describe any product we sell as road-legal, approved, marked or certified. Check the visor in your hands.
Nine mistakes that keep riders fogging
- Closing the chin vent in winter. The vent that feels worst on your face is the one aimed at the visor.
- Wiping a dry visor. One pass with a glove can remove the anti-fog coating exactly where you look.
- Fitting an insert without enough pin tension. Fog between the lenses is a seal problem, not a product problem.
- Leaving the peel-off film on an insert. Commoner than anyone admits.
- Wearing a buff over the nose. It pipes saturated air straight onto the visor.
- Using household glass cleaner. Ammonia attacks coatings and polycarbonate.
- Riding a tinted visor into the dark rather than swapping, then lifting it constantly, which floods the inside with warm air.
- Blocking the rear exhausts. A rucksack riding high can stop the whole airflow path.
- Treating an insert’s anti-fog face like glass. It is an absorbent layer; water only, air-dry.
Frequently asked questions
Why does my visor only fog when I stop?
At road speed, air moving through the helmet carries moist air out and keeps the inner visor surface swept. When you stop, that airflow stops with you, while your breathing continues and the visor keeps losing heat to the outside air. Condensation forms within seconds. Cracking the visor to its first detent and opening the chin vent is the standard fix, and an anti-fog insert removes the problem rather than managing it.
Do anti-fog inserts really work?
Yes, and they work by a different mechanism from sprays and coatings. An insert traps a sealed pocket of air against the visor, insulating the inner surface so it stays above the dew point and condensation never forms. Sprays and coatings let condensation form and make it optically harmless instead. In sustained cold and wet the insert is markedly more effective, which is why it is the first upgrade we suggest.
Will an anti-fog insert fit my helmet?
It depends on the visor rather than the helmet shell. If your visor has two small pins or two small holes near the lower edge on each side, it is drilled for a pin-style insert, and if it has neither, many helmets can take a pin-drilled replacement visor instead. Check your exact helmet model against our visor finder or the relevant brand page, since fitment varies between models from the same manufacturer and sometimes between production years.
What is the difference between the 70 and 120 insert grades?
The number describes how much light the insert transmits. The higher-clarity option passes more light and is the better choice for night riding and dark winter conditions. The lower-clarity option typically carries a more aggressive moisture-absorbing layer and resists fogging harder in extreme damp, at the cost of some light. Most UK riders are better served by the higher-clarity grade.
Can I use washing-up liquid or toothpaste on my visor?
A very dilute smear of washing-up liquid buffed almost dry does reduce beading, because it is a surfactant, but residue refracts light badly at night and it is easy to overdo. Toothpaste should never be used: it is a mild abrasive designed to polish tooth enamel, and on polycarbonate it leaves a haze of fine scratches that becomes obvious against oncoming headlights. A purpose-made anti-fog product, or better an insert, is the right answer.
Are tinted or iridium visors legal on UK roads?
The legal test is the marking on the individual visor, not its colour. For road use in Great Britain an eye protector is expected to carry a BS 4110 grade with an approved certification mark or an ECE 22.05 approval. Iridium, mirrored and dark-smoke finishes transmit too little light to be legal for road use in the UK, in daylight as much as at night. Selling one as authorised for road use when it is not a prescribed type is a seller offence under section 18(4) of the Road Traffic Act 1988, carrying a fine to a maximum of £1,000 and no penalty points.
How do I stop my glasses fogging inside my helmet?
Fix the airflow first: open the chin vent, make sure the rear exhausts are clear, and fit the breath guard that came with your helmet. Keep any neck tube below your chin rather than over your nose. Use an anti-fog product intended for optical lenses rather than one intended for visors, since many spectacle coatings are damaged by the wrong formulation, and remember that a helmet with spectacle channels in the cheek pads holds the lenses in better airflow.
Does a chin curtain help or make fogging worse?
Both, depending on conditions. A chin curtain reduces the cold draught that chills the visor, which helps, but it also restricts the escape route for moist air, which hurts. Most riders find it helps in cold dry weather and hurts in mild wet weather. It is removable on most helmets, so it is worth riding the same route with and without before deciding.
Where to go next
If you take one thing from this guide, make it the order of operations: insert first, ventilation second, breath management third, chemistry last. That order reflects how much each one actually moves the physics.
To act on it, start with pin-style anti-fog inserts and check fitment for your helmet with the visor finder. If your visor is scratched, hazed or has lost its coating, a replacement is the cheaper half of the job — browse clear visors, photochromic visors, or the full range. Shipping is free on every order.