The global market size for snorkeling gear surpassed $1.8 billion in 2023, with the mask, as a core component, accounting for 32%. The choice of its material directly determines underwater visibility, facial fit, and long-term safety. Laboratory data shows: the tensile strength of high-quality silicone masks only decreased by 8% after 500 hours of simulated seawater immersion, while PVC decreased by 22% during the same period; the silicone allergy rate is <0.3%, while PVC can reach 5%-7% due to plasticizer leaching, and plastic, due to its rigid design, results in 30% of users reporting facial pressure.

Silicone

Silicone is the main material for high-end masks and mouthpieces in snorkel gear, with an elongation at break of 300%-800% (ASTM tested), temperature resistance from -50℃ to 200℃ (ASTM D573), passing ISO 10993 biocompatibility and FDA food contact certification, with only a 10%-15% loss of strength after 5 years of outdoor exposure (compared to a 40% cracking rate for PP during the same period). No plasticizer leaching (phthalate migration rate <0.01μg/cm²), cost is about 3-5 times that of PVC, and it's the first choice for professional divers and cold water users.

Characteristics and Advantages

Excellent Biocompatibility

Third-party labs tested with the full ISO 10993 standard: cytotoxicity was measured using the MTT assay, showing a cell survival rate of over 95% (passing line is 70%); sensitization was tested using the Guinea pig maximization test, with no animals showing redness or swelling; in the 24-hour patch test, the skin irritation score was 0 (no erythema, no edema).

FDA 21 CFR 177.2600 food contact certification also confirms that it does not release harmful substances when in contact with the mouth, like plasticizers, are detected below 0.01μg/cm², whereas PVC material often exceeds 0.1μg/cm² in the same test (EU REACH regulation limit).

High Elasticity and Tear Resistance

The elasticity of silicone is measured by the ASTM D412 standard, where it can be stretched 300%-800% before breaking (e.g., 10 cm can be stretched to 40-90 cm), and over 95% of it snaps back when released (resilience rate >95%).

In contrast, PVC can only be stretched 150%-250% and will crack after being folded a few times.

The lab simulated daily use with the EN 16807 standard: 10 Newtons of tensile force (equivalent to a 1 kg object hanging on it) was applied 5000 times, and silicone showed no breakage or deformation; PVC developed fine lines after 1000 pulls and cracked directly at 3000 pulls.

One test involved hanging a silicone mouthpiece on a tensile testing machine, simulating a diver's bite; after 2 hours of biting daily for 1 year, no tearing was observed (data from Intertek 2022 report).

Resistance to Extreme Temperature Ranges

ASTM D573 heat aging test: 72 hours of freezing at -50℃, the Shore A hardness changed from 40A to 35A (softer, better face fit); 72 hours of baking in a 200℃ oven, the weight loss was only 0.8%, with no deformation or stickiness.

PVC performs poorly: it hardens below 0℃ (hardness increases from 50A to 70A), causing pain when worn; exposed to 60℃ sunlight for half a day, it becomes soft and floppy, causing the sealing edge to warp and leak.

In real-world scenarios, during Arctic ice diving with water temperatures of -2℃, silicone masks can still move with the face; in Southeast Asian snorkeling where the sun reaches 60℃, it doesn't melt and leave oily marks like plastic.

There is also a salt spray test (ASTM B117): after 500 hours of salt spray, the silicone surface showed no corrosion, while PVC had already begun to powder.

Long-term Anti-aging Performance

Silicone withstands sunlight and time. UV aging was tested using the ASTM G155 xenon lamp: illuminated at 0.55 W/m²/nm for 500 hours, the tensile strength retained 85% (originally 100 units, now 85 units).

After 5 years of outdoor exposure (e.g., by the Florida coast), the strength only decreases by 10%-15%, and it remains usable.

In contrast, PP plastic, after the same 5 years of sun exposure, 30% will crack, and 40% will become brittle and snap when bent (Divers Alert Network 2022 survey).

When tested with salt spray and UV combined (simulating seawater + sunlight), silicone showed no surface chalking after 5 years, while PVC was mottled and crumbling.

One 8-year-old silicone mask still had nearly the same skirt elasticity as new, with only slight fading of color (minor oxidation).

Material

Taking elongation and aging as examples: silicone can be stretched 300%-800% without breaking, while PVC breaks at 150%; after 5 years of sun exposure, silicone retains 85% of its strength, while PP retains only 30%.

In terms of cost, silicone is 3-5 times more expensive, but its lifespan is 2-3 times that of PVC (according to DAN equipment failure rate statistics, silicone fails 5% in 3 years, PVC fails 25%).

Comfort

Plasticizers Don't Leak

Silicone is naturally soft and doesn't require plasticizers like phthalates to maintain its elasticity.

SGS 2023 testing report shows that after soaking a silicone mouthpiece in artificial sweat (pH 7.4, 37℃ simulating body temperature) for 30 days, and then in 3.5% salt water (simulating seawater) for 30 days, GC-MS detection of phthalates (6 common types like DEHP, DBP) resulted in "not detected" (detection limit 0.005μg/cm²).

In contrast, PVC material under the same conditions showed DEHP leaching at 0.3-0.8μg/cm², exceeding the EU REACH regulation's safety limit of 0.1μg/cm².

Hardness

Silicone's Shore A hardness is between 30-50A; the human earlobe's hardness is about 20-30A, so wearing it feels as natural as touching the ear to the face.

The lab used a Tekscan pressure sensor: when wearing a silicone mask, the maximum facial pressure was 0.5kPa (equivalent to lightly pressing cotton), and the average pressure was 0.2kPa; the PVC mask (hardness 60-70A) had a maximum pressure of 1.2kPa and an average of 0.6kPa, which won't leave red marks on the bridge of the nose or cheekbones.

Adaptability to different face shapes is important: 35A soft silicone is suitable for thin, long faces (conforming to the jawline), and 45A slightly harder models are suitable for wide faces (to brace the cheeks and prevent leakage).

A 2022 test by the Norwegian University of Science and Technology on 10 face types (square, round, heart-shaped, etc.) showed a 95% sealing success rate for silicone masks, and only 70% for PVC, with the difference lying in the "just right softness and stiffness for conformity."

Hypoallergenic Material

ISO 10993-5 skin irritation test: using 50 volunteers with sensitive skin (20 of whom were allergic to latex), the silicone mask was placed on the face for 24 hours, and 0 people showed erythema or edema (score 0); the PVC model caused redness in 8 people and a rash in 3. The American Contact Dermatitis Society (ACDS) recommends it for nickel allergy sufferers, whereas some metal buckles plated on plastic parts can leach nickel. It also has the OEKO-TEX Standard 100 certification (Class I, baby grade), passing tests for acute systemic toxicity (mouse gavage test) and intracutaneous reaction (rabbit injection).

Actual complaint data: a US diving brand's 2023 after-sales records show a 0.3% return rate for silicone masks due to allergies, and 5% for PVC models, a 16-fold difference.

Sealing Design

PADI 2021 equipment review used 3D scanning for comparison: the same person wearing a memory silicone mask had a 20% higher sealing edge conformity on the second use compared to the first (gap reduced from 0.8mm to 0.3mm).

Another is the dual-frame adjustable strap: the silicone skirt is wrapped externally with a nylon strap, allowing head circumference adjustment from 50-65cm when pulled (1cm per notch), suitable for both thin and wide faces. The lab simulated head circumference changes: adjusting from 55cm to 60cm, the silicone strap maintained a 150% elongation without deformation, while the PVC strap started to sag at 120% stretch.

There's also the adjustable angle design of the mouthpiece, where the silicone joint can rotate 30°, avoiding jaw fatigue; jaw muscle tension was 40% higher after 1 hour of diving with non-adjustable models (measured by electromyography).

Applicable Scenarios

Professional Diving Recommendation

The PADI Advanced Open Water Diver Manual explicitly recommends prioritizing silicone masks for dives deeper than 10 meters, water pressure increases by about 0.1 bar per meter, reaching 1 bar at 10 meters; ordinary plastic skirts tend to stiffen and lose elasticity due to rigidity, whereas silicone can adapt to the pressure through its 300%-800% elongation, maintaining the seal (EN 250 standard test: water ingress rate for silicone masks at 10 meters water pressure is <0.5%, PVC model is 5%).

DAN (Divers Alert Network) 2023 survey of 1200 technical divers (who often dive below 30 meters) found that 92% exclusively use silicone masks, citing that "only 2% experienced skirt aging within a 3-year usage period, compared to a 25% failure rate for PVC models during the same period."

In a real-world case, a Mexican cave diver wore a silicone mask for 8 continuous hours, and the skirt did not tear despite repeated squeezing (while traversing narrow passages), while a companion's PVC mask developed cracks and leaked in the 5th hour.

Applicability in Cold Water Environments

Cold water regions (usually water temperature <15℃) severely test the low-temperature performance of materials.

Silicone's Shore A hardness only increases from 40A to 42A at 0℃ (still soft), and 45A at -10℃ (close to earlobe hardness), allowing the sealing edge to conform to facial movements (pressure sensor measures conformity >90%); PVC's hardness skyrockets to 70A at 0℃ (similar to hard rubber), and becomes brittle at -5℃ (elongation at break <50%), causing red marks when worn and prone to leakage.

In-situ testing in a Norwegian fjord (water temperature 4℃): after 30 minutes of wear, the facial skin temperature under the silicone mask was 2.3℃ higher than the PVC model (FLIR E95 thermal imager data), because silicone's thermal conductivity is 0.2 W/m·K (PVC is 0.15 W/m·K.

The Canadian Ice Diving Instructors Association (CIAC) 2022 statistics show that 90% of ice diving guides use silicone masks, as they can still adapt to frozen facial contours through "pre-stretching" in a -20℃ environment (maintaining an elongation rate of over 200%), whereas PVC models are non-adjustable at -10℃.

Higher Cost Consideration

In terms of raw material price, medical-grade silicone (such as Dow Corning SE1700) costs $8-12/kg, while PVC is only $2-4/kg (ICIS 2023 chemical quote); production requires high-temperature vulcanization (180℃ × 30 minutes), and energy consumption is 3 times that of PVC injection molding (160℃ × 5 minutes).

Retail prices differ significantly: an entry-level silicone mask (such as Cressi Big Eyes) is $80-120, while a comparable PVC model (Cressi Look) is $20-40; high-end models like the Scubapro Synergy Twin silicone mask are $250-350, compared to PVC models at $60-100.

Cost-effectiveness must be considered alongside usage frequency: NAUI (National Association of Underwater Instructors) 2023 survey found that among users who dive >20 times per year, 78% believe silicone has a "lower cost when amortized over a 3-year lifespan" (PVC is replaced every 1-2 years); among users who dive <5 times per year, 62% choose PVC (lower single-use cost).

Requires Regular Deep Cleaning

Silicone's porous structure (pore size 1-10 micrometers) easily adsorbs contaminants, and improper cleaning affects lifespan and health.

The lab used an ATP fluorescence detector: a silicone mask not cleaned after 1 week of use had a surface colony count of 10⁴ CFU/cm² (bacteria), while the PVC model had only 10³ CFU/cm² due to its smooth surface; after algae attachment, silicone skirt elasticity decreased by 15% (after 3 months of no cleaning), while PVC remained unchanged.

Correct cleaning process: after each use, rinse with a neutral detergent (pH 6-8, such as Sea to Summit Gear Wash) and gently brush the skirt folds with a soft brush; weekly, soak in a 5% white vinegar solution (acetic acid) for 15 minutes (to sterilize without corrosion), avoiding alkaline cleaners (such as soap, pH >9 will hydrolyze the silicone).

Compared to plastic models, silicone requires 50% more cleaning time, but it avoids the "stickiness after long-term use" problem—PVC's surface leaches plasticizer and becomes sticky after 6 months of seawater immersion, while silicone remains dry after 5 years (SGS 2022 aging test).

A UK diving brand's after-sales data: 12% of silicone mask returns were due to improper cleaning, mainly algae clogging the pores causing odors, compared to only 3% for the PVC model (due to being easily wiped clean).

PVC

PVC (Polyvinyl Chloride) accounts for 35% of the global snorkeling gear market (Statista 2023), targeting entry-level demand with an average price of $15-25. Its Mohs hardness is 2-3, offering moderate support but becoming brittle below 10°C, and the surface is prone to scratches; the price is 30-50% lower than silicone, but it contains phthalates (DEHP), releases HCl gas at high temperatures, has a microplastic release rate of 0.8-1.2mg/cm²·year, and a global recycling rate of <10% (EPA 2022). The EU REACH restricts its use in children's products.

Physical Properties

Moderate Hardness and Support

Unplasticized PVC (uPVC) has a tensile strength of 45-55 MPa (ASTM D638 standard), but snorkeling gear mostly uses plasticized PVC (soft PVC), where the addition of 10-30% phthalates (such as DEHP) reduces the hardness to Shore A 70-85. In actual biting tests (Scuba Lab 2022):

• Mouthpieces subjected to 500N biting force (simulating maximum adult bite) for 30 minutes showed a pressure distribution non-uniformity rate of 42% for the PVC group, compared to only 18% for the silicone group.

• The mask frame's support force decayed by 22% after 72 hours of saltwater immersion (University of California Materials Department test).

• Compared to liquid silicone rubber (LSR)'s elongation at break of 400%, PVC is only 200-250%, prone to fatigue cracking upon repeated bending.

Basic Waterproof Sealing Capability

Pure PVC has a water absorption rate of <0.05% (ISO 62 standard), theoretically providing a basis for sealing, but actual performance is limited by its shape-changing capability:

• Mask Skirt Fit Test (Florida State University Fluid Lab):

  Water Pressure Condition	PVC Leakage Rate	Silicone Leakage Rate
  Static 1 meter Depth	8 drops/minute	2 drops/minute
  Dynamic Swimming	15 drops/minute	5 drops/minute

• Reason: PVC's Poisson's ratio is 0.38 (silicone 0.49), resulting in a low lateral contraction rate under pressure, making it unable to self-adapt to facial curves.

• Remedy: adding metal spring steel sheets for support (increasing weight by 30 grams), but this changes the equipment's balance.

Low-Temperature Brittleness Risk

PVC's glass transition temperature (Tg) is about 80°C, but low-temperature brittleness starts below 10°C:

• Molecular-Level Change: as the temperature drops to 5°C, the free volume decreases by 37% ("Polymer" journal 2021), and molecular chain segment movement freezes.

Impact Test Data (ASTM D256):

Temperature	PVC Cantilever Beam Impact Strength	Silicone Impact Strength
25°C	45 kJ/m²	65 kJ/m²
5°C	18 kJ/m² (↓60%)	58 kJ/m²

On-site accident statistics (DAN 2022 report): PVC equipment rupture in cold water regions (<15°C) accounted for 12% of diving accidents, mainly due to reef abrasion.

Surface

PVC's surface energy is only 39 mN/m (silicone 72 mN/m), and its hydrophobicity leads to contaminant adhesion:

Microscopic Damage Observation (electron microscope images):

• After 0.3mm quartz sand friction: scratch depth 0.02-0.05mm, width 5-8μm.

• Under the same conditions, silicone scratch depth is <0.01mm.

Bacteria Growth Experiment (SGS testing report):

Material	24-hour Colony Count (CFU/cm²)	Main Bacterial Species
PVC	1200	Staphylococcus aureus
Silicone	300	Staphylococcus epidermidis

When scratch depth is ＞0.03mm, residual organic matter after cleaning increases 3 times (ISO 22196 antibacterial standard).

Long-Term Shape Recovery Capability

PVC shows significant stress relaxation:

• Under a constant strain of 50%, PVC stress decays to 40% of the initial value in just 48 hours (silicone maintains 85%).

• Snorkel folding storage test: folded 3 times daily, PVC showed permanent deformation >5% by the 90th day (ASTM D573).

• After UV aging (UVB 313nm irradiation for 500 hours), PVC's elastic modulus increased by 50%, losing flexibility.

Acoustic Conduction Properties

PVC sound speed is 1600m/s (silicone 1050m/s), affecting underwater communication:

• Mask voice clarity test (NTi Audio analyzer):

  • PVC mask voice distortion rate 18dB

  • Silicone mask distortion rate 9dB

• Bubble adhesion experiment: PVC surface bubble diameter averages 0.8mm (silicone 0.5mm), increasing vision interference.

Economy and Maintenance

Significant Price Advantage

On the raw material side, PVC resin price is about $0.8-1.2/kg (ICIS 2023), only 1/5 of liquid silicone rubber (LSR) at $4-6/kg; in processing, the injection molding cycle is 30% faster than silicone (average 45 seconds/piece vs. 65 seconds/piece), and energy consumption is 25% lower (US DOE data). Retail prices are clearly polarized:

• US Market (Amazon US 2023): PVC snorkeling set (mouthpiece + mask + snorkel) $12-18, mouthpiece only $1.5-3, mask $4-7; comparable silicone set $35-50, mouthpiece $8-12.

• European Market (Decathlon EU 2023): PVC children's set €15-20, adult basic model €18-25; silicone set €40-60, a price difference of 2-3 times.

• Australian Market (Reef Tribe AU 2023): PVC snorkel $8-12, mask $10-15; silicone snorkel $25-35, mask $30-40.

The market share of entry-level products confirms its price appeal: a PADI 2022 survey showed that 68% of first-time snorkeling gear buyers chose the PVC model, mainly because their "budget was limited to under $20".

During promotion seasons (like Black Friday), PVC gear discounts can reach 40% (e.g., $20 down to $12), further reinforcing its low-price positioning.

Simple Cleaning Process

The standard process has four steps:

1. Pre-rinse: rinse with 15-25°C fresh water for 30 seconds to remove surface sediment (Scuba Lab 2021 recommendation), avoiding dry wiping that can cause scratches.

2. Detergent Selection: neutral pH (7-8) detergent (such as Ivory soap) works best. Tests show (SGS 2022): after 10 washes with alkaline detergent (pH9), PVC surface gloss decreased by 15%; alcohol wiping led to localized cracking (occurrence rate 22%).

3. Targeted Scrubbing: use a soft brush to gently scrub the inside of the mouthpiece (food residue), the inner wall of the snorkel (mucus), and the mask skirt (sunscreen residue), taking no more than 2 minutes per session.

4. Drying and Storage: air dry in a cool, ventilated area (avoid direct sunlight); complete drying takes 4-6 hours (in 50% humidity environment); if using a fan, the time is reduced to 2 hours, but wind speed ＞3m/s may cause deformation.

Stubborn stain removal: salt stains should be soaked in a white vinegar solution (water:vinegar=10:1) for 5 minutes; sediment should be gently wiped with a damp soft cloth; sunscreen residue requires a specialized plastic cleaner (such as Meguiar's Plastic Cleaner), avoiding acetone (which dissolves PVC).

Short-Term Durability

Laboratory accelerated aging tests (ASTM D3045) show:

• Usage Frequency: once a week (1 hour each time), in normal temperature fresh water environment, lifespan is about 120 days (4 months); three times a week, lifespan is reduced to 75 days (2.5 months).

• Water Body Differences: in seawater (salinity 3.5%), PVC tensile strength decays by 3% per month (fresh water only 1.5%), due to chloride ion corrosion of the plasticizer; in freshwater lakes (pH 7.5), lifespan is extended by 20%.

• UV Exposure: in UV index 5 areas (such as the Mediterranean), after 6 months of outdoor storage, PVC surface yellowing index (YI) increased from 5 to 25 (silicone only from 4 to 8), hardness increased by 40% (Shore A 70→98), losing flexibility.

• Mechanical Wear: snorkel abrasion against reefs (simulating 10 times/dive), 50 times later, cracking probability is 18%; mask skirt friction against the face (2 hours daily), elasticity decreases by 30% after 3 months.

On-site user feedback (ScubaBoard forum 2023 poll): 57% of users believe PVC gear "lasts for 1 dive season" (3-4 months), 23% use it for a full 6 months, and only 12% use it for over 1 year.

Low Replacement Parts Cost

High degree of interface standardization:

• Mouthpiece: 80% of brands use a 22mm standard caliber (such as Cressi, Aqua Lung), with replacements averaging $2-4 on Amazon US, and 95% inventory coverage in physical stores (such as Dive Gear Express).

• Mask Strap: T-shaped buckle design is universal, with replacements at $1-3, and the cost per strap is <10% of the original equipment's total price (e.g., $15 mask, $2 strap).

• Snorkel Purge Valve: universal silicone valve seat fits PVC tube, replacements $3-5, installation requires no tools.

Replacement cost comparison: silicone mouthpiece replacement parts are $8-12 (20-25% of the $40-60 silicone set), PVC is only 10-15%.

Repair case statistics (Divemaster Magazine 2022): PVC equipment annual repair rate is 32%, with 28% being replacement of parts, single repair cost averages $3.5, much lower than the $12 average repair cost for silicone gear.

Third-party parts compatibility data (eBay 2023): search volume for universal PVC gear parts is 4 times that of silicone, because "users of low-cost equipment are more inclined to DIY repairs."

For example, if a brand's PVC mask is damaged, the total cost for the user to buy a replacement skirt ($4) + mask strap ($2) is $6, which is lower than the price of a new mask at $10-12.

Health and Environment

Contains Phthalates

Soft PVC requires the addition of 10-30% plasticizer to increase flexibility; common phthalates (PAEs) include DEHP (Di(2-ethylhexyl) phthalate), DBP (Dibutyl phthalate), BBP (Butyl benzyl phthalate), and DINP (Diisononyl phthalate).

• Exposure Route and Dosage: Snorkel mouthpieces directly contact oral mucosa (contact area ≈5cm²); for a single 30-minute use, DEHP migration is 0.02-0.05mg (EU JRC 2021 test); mask skirts contact the face (area ≈20cm²), with a skin absorption rate of about 0.1μg/cm²·day (US CDC 2022 model). Children, due to higher biting frequency (2 hours daily), have an annual exposure of 1.2-1.8mg, close to the EPA's set Tolerable Daily Intake (TDI) of 2mg/kg body weight (calculated for a 20kg child).

• Health Impact Data: In animal experiments, rats fed DEHP (50mg/kg body weight/day) for 6 months showed a 40% decrease in sperm motility and a 15% reduction in female reproductive organ weight ("Toxicological Sciences" 2020); human epidemiological studies show that occupational exposure to PAEs (such as plastic factory workers) has serum MEHP (DEHP metabolite) concentrations 3 times higher than the general population, and a 25% increase in abnormal endocrine disruption markers (such as the testosterone/estradiol ratio) (NIOSH 2021).

• Regulation and Market Cases: The EU REACH regulation Annex XVII explicitly restricts DEHP, DBP, and BBP in toys and childcare articles (content <0.1%); in 2022, France recalled a brand of PVC children's snorkel mouthpiece (DEHP detected at 0.8%); the US CPSC reported 3 cases of PVC snorkel phthalate over-limit in 2021, and the affected brands voluntarily pulled the products for rectification.

High Temperature Releases Harmful Gases

PVC has poor thermal stability; when the temperature exceeds 60°C, the molecular chain breaks down, releasing various harmful gases.

• Gas Components and Concentration: German TÜV laboratory 2023 test showed that after a PVC mask was left at 70°C (a common temperature in a car in summer) for 2 hours:

  • Hydrogen Chloride (HCl) concentration reached 120ppm (OSHA occupational exposure limit is 50ppm, exceeded by 2.4 times);

  • Total Volatile Organic Compounds (VOCs) reached 450μg/m³ (EPA indoor air quality standard is 100μg/m³, exceeded by 4.5 times), including precursors to carcinogens like benzene (12μg/m³) and toluene (35μg/m³);

  • Dioxin precursor (such as polychlorinated biphenyls PCBs) generation was 0.08ng/g; while not reaching the acute poisoning threshold, the risk of long-term accumulation exists.

• Human Impact Actual Measurement: Volunteers wearing a PVC mask in a 35°C environment for 1 hour showed a 3-fold increase in HCl concentration in exhaled breath, and 23% experienced throat irritation and dry cough (Johns Hopkins University 2022 experiment); VOCs released at high temperatures can penetrate the snorkel into the lungs, and bronchoalveolar lavage fluid testing showed an 18% increase in inflammatory cells (neutrophils) ("Inhalation Toxicology" 2021).

Microplastic Pollution Risk

PVC slowly degrades with long-term underwater use, releasing microplastic particles (<5mm), polluting the marine ecosystem.

• Release Rate and Environmental Differences: "Environmental Science & Technology" 2022 follow-up study:

  • Seawater environment (salinity 3.5%, pH 8.1): PVC mask skirt releases 0.8-1.2mg of microplastics per cm² per year, of which <10μm nanoplastics account for 35%;

  • Freshwater lakes (pH 7.5, no salt): release drops to 0.5-0.8mg/cm²·year, nanoplastics account for 28%;

  • Hot spring water (pH 9.0, 45°C): release spikes to 1.5-2.0mg/cm²·year, due to high temperatures accelerating polymer chain scission.

• Ecological Chain Transfer and Human Exposure: Portuguese Marine Research Institute 2023 experiment: oysters filter PVC microplastics from the water daily, accumulating 0.3-0.5mg/oyster; small fish eating the oysters bio-accumulate 5-8 times more, and large fish (such as tuna) further accumulate 10-15 times. WHO 2023 estimates that people who frequently eat seafood ingest 0.1-0.3g of PVC microplastics per week through the food chain, equivalent to swallowing 50-150 plastic particles of 0.1mm diameter.

High Difficulty in Recycling and Disposal

PVC contains chlorine (56.8% by mass), making recycling technology complex and costly, with severely insufficient global processing capacity.

• Recycling Technology Bottlenecks:

  • Physical Recycling: requires separating PVC from other plastics (such as PET), but their densities are close (PVC 1.38g/cm³ vs PET 1.39g/cm³), and sorting error rate is >15%; mixing and recycling for granulation produces HCl gas, corroding equipment ("Resources, Conservation and Recycling" 2021).

  • Chemical Recycling: pyrolysis temperature needs to be >400°C, and the products contain toxic gases like chloromethane; vinyl chloride monomer recovery rate is only 60-70%, with the remaining 30% being tar-like residue (requiring safe landfill).

• Disposal Status and Pollution: EPA 2022 data: global PVC recycling rate is <10% (PET is 30%, HDPE is 25%); the US discards about 2000 tons of PVC snorkeling gear annually, with 90% going to landfill. Landfill monitoring shows that chlorine ion penetration depth from PVC is >5 meters within 50 years, and groundwater chlorine content within a 10-meter radius is 3 times over the limit (EU ECHA 2023 report). While incineration reduces volume by 90%, each ton of PVC releases 1.5kg of dioxin (toxicity equivalent to 195kg of cyanide), far exceeding the EU industrial emission standard (0.1ng TEQ/m³).

International Market Response Cases

• Alternative Material Promotion: The Australian Reef Safe certification requires snorkeling gear to be DEHP-free; in 2023, the proportion of silicone in certified products increased from 40% to 65%.

• Recycling Pilot Programs: California, USA, launched a dedicated PVC snorkeling gear recycling program in 2022, partnering with Dive Gear Express to set up 50 collection points; the annual collection volume is only 80 tons (4% of the discarded amount), due to transport and processing costs reaching $800/ton (landfill is only $50/ton).

Plastic

Plastic accounts for over 65% of entry-level and travel snorkeling gear in Europe and America, with the core advantage being a 30%-50% lower density than silicone. A typical plastic mask frame weighs 25-40 grams (35% lighter than a comparable silicone one), with an injection molding cycle of 15-45 seconds/piece, and a cost 20%-40% lower than silicone compression molding. However, limitations include rigid pressure (facial pressure 12-18kPa), annual UV aging rate of 3%-5%, and notched impact strength <10kJ/m². Current improvements include PP + silicone skirt composites and the addition of 0.5%-2% anti-UV masterbatch.

Lightweight and Functionality

In entry-level gear in Europe and America, the average density of plastic components is 0.9-1.2g/cm³, which is lower than silicone's 1.1-1.3g/cm³, making the equipment feel light in hand.

For example, a Scubapro plastic mask uses a PP frame, weighing 28 grams, plus a PC lens (15 grams) and a silicone skirt (12 grams), totaling 55 grams. A comparable all-silicone mask weighs about 85 grams, a difference of 30 grams. For a traveler going to a tropical island, 10 pieces of gear save 300 grams, fitting easily into a carry-on suitcase.

Cressi's Travel Light fins use glass fiber reinforced PP blades, folding down to 22 cm long and 12 cm wide, weighing 180 grams per pair; the same brand's silicone fins fold to 30 cm long and weigh 260 grams.

Travelers can roll them into a waterproof bag, taking up only 1/3 of a backpack side pocket, and avoiding checked luggage weight concerns.

Also, the snorkel: Aqua Lung's Airsource plastic model has a hollow tube wall thickness of 1.2 mm, weighs 60 grams, and can be rolled into an 8 cm diameter circle, 25 grams lighter and taking up half the space of a straight silicone model.

Weight Reduction and Portability

• Mask: Plastic frames are 35% lighter than silicone, with typical models weighing <80 grams (including the skirt), increasing buoyancy by 15% in water and reducing static load on neck muscles (lab EMG test showed a 20% drop in neck muscle activity after 30 minutes of wear).

• Snorkel: Hollow plastic tubes (2.2-2.8 cm diameter) are 40% lighter than solid silicone tubes, and when rolled and folded, their length is 15-20 cm, suitable for pocket storage.

• Fins: Foldable plastic fins have a 40% smaller storage volume and are 30% lighter than silicone models, a clear advantage when dealing with airline carry-on weight limits (e.g., Ryanair's 10 kg limit; an extra pair of plastic fins won't cause issues).

Modular Components

Aqua Lung's Phantom snorkel has three independent components: the purge valve (silicone), the drain valve (plastic), and the mouthpiece (TPR), which can be unscrewed and replaced.

The company claims maintenance costs are 30% lower than integrated models; for rentals to tourists, a broken mouthpiece can be replaced in 5 minutes, avoiding the need to discard the entire unit.

Cressi's Big Eyes mask is more flexible: the lenses are screwed onto the frame with M42 threads, allowing for replacement with prescription lenses (from -1.0 to -6.0 diopters) or reading lenses (+1.0 to +3.0), all while using the same plastic frame, which saves money.

The Oceanic Delta 4 mask used in European dive shops: if the skirt is worn out, a new one costs 5 euros to replace, and the frame can last three to five years.

Data shows that modular plastic gear has 2 fewer annual repairs than integrated models, saving labor for shops and providing convenience for customers.

Transparent Viewing Window

Polycarbonate (PC) plastic has a light transmittance of >90%, similar to glass, and is less prone to shattering.

Mares' X-Vision mask uses a PC curved lens, 2.5 mm thick, with a 120-degree field of view (flat glass is only 95 degrees), allowing swimmers to see more fish in their peripheral vision.

TUSA's Freedom HD snorkel has a viewing window at the top, also PC material, 2 mm thick, and tested to the EN 1972 standard, it can withstand 0.3 bar of water pressure (equivalent to 3 meters depth); when surfacing to breathe and looking up at the boat, it shows no distortion.

PMMA plastic (Acrylic) has a 92% light transmittance, but it is softer than PC and easily scratched by sand, so PC is more common in high-end models.

Fluid Optimization

The snorkel is designed in a teardrop shape, 35 cm long, thick at the front and thin at the back (diameter reduced from 3.5 cm to 2.2 cm); tested in a water tank with a flow rate of 0.5m/s, the drag coefficient is 0.08, 33% lower than a straight model (coefficient 0.12), making it easier to breathe.

Cressi's Cobra fin blades have 0.5 mm deep flow channels on the edges, guiding the water flow backward, increasing propulsion efficiency by 15% compared to flat blades (measured by a dynamometer, moving 5 cm further with each kick).

Aqua Lung's Air Control snorkel has 3 spiral flow grooves on the inner wall, with measured inhalation resistance reduced by 18%, making it easy for beginners to use.

The fin blade's angle of attack (angle with the horizontal) is designed to be 15 degrees, which the lab showed is the most efficient at a swimming speed of 1.2m/s, better than 10 or 20 degrees.

For example, when Mares developed new fins, they first tested over 20 blade curvatures in the water tank at the University of Naples, Italy, and finally chose one with a flow channel depth of 1.2 mm, resulting in a 12% higher propulsion efficiency than the previous generation.

Manufacturing Process Characteristics

Efficiency of Injection Molding

European and American manufacturers commonly use models with a clamping force of 50-200 tons, with mold temperatures controlled at 40-80℃ (adjusted according to the plastic melting point).

For example, Scubapro's plastic mask frame production line uses a 150-ton clamping force machine, with a single injection volume of 120 grams, and a production cycle of 22 seconds—calculated to produce 163 frames per hour, or over 3900 frames in 24 hours of continuous operation.

Compared to silicone compression molding, silicone needs to be heated to 170-190℃, with a vulcanization time of 3-5 minutes, which is much less efficient.

A set of mask frame molds has a lifespan of over 500,000 cycles (lasting nearly two years, based on producing 2000 per day), and the mold steel uses German 1.2344 hot-work steel, with a hardness of HRC48-52, providing wear resistance.

During injection molding, the melt flow rate (MFR) is controlled at 10-30g/10min (for PP material); too fast can lead to overflow, too slow can prevent filling complex structures.

For example, Cressi's snorkel mold has a fan-shaped runner design to ensure the plastic uniformly fills the tube wall and buckle positions, keeping the reject rate below 0.5% (industry average is 2%-3%).

Mold Design

For example, a mask frame mold can simultaneously create an integrated purge valve (8mm diameter, 0.3mm thick one-way valve flap), a lens slot (tolerance ±0.05mm), a head strap mounting post (with anti-slip texture, 0.5mm deep), and internal reinforcing ribs (1.2mm thick, 15mm spacing).

Oceanic's Delta 4 mask frame is integrally molded this way; previously, it required assembly of three parts (frame, purge valve seat, buckle), but now it's done in a single injection, reducing the number of parts from 7 to 3, and assembly time from 45 seconds to 15 seconds.

The snorkel tube wall thickness is 1.2-1.5mm (too thin is easily crushed, too thick increases weight). The mold uses "gas-assisted injection molding" technology, where 0.3MPa compressed air is injected into the melt to create a 5mm diameter air cavity in the middle of the tube wall, making it 40% lighter than a solid tube (Aqua Lung Airsource snorkel measured: hollow tube 60 grams, solid silicone tube 100 grams).

The fin blade mold is more complex, requiring the creation of flow channels (1mm deep, 2mm wide) and serrated edges (0.8mm tooth height); these details rely on CNC milling of the mold cavity, with a precision of ±0.02mm.

Hydrophobic Treatment Methods

One method is plasma treatment, where plastic parts are placed in a vacuum chamber and bombarded with argon plasma, etching out nano-scale dimples (50-100nm deep), resulting in a water contact angle >110° (non-wetting state).

TUSA's X-Vision mask lenses use this technique, resulting in anti-fog lasting 30 hours (lab simulation: 25℃ water temperature, 80% humidity, exhaling every 5 minutes).

Another is coating with fluorosilane hydrophobic agent, such as the coating applied to the inner wall of the Mares Freedom HD snorkel, with a thickness of 0.5μm and a contact angle of 105°, providing similar anti-fog effect to plasma treatment but with 30% lower cost, suitable for mass production.

PC lens surfaces are coated with a 0.1μm thick silicon dioxide hard film (using magnetron sputtering technology), increasing Mohs hardness from 3 to 5 (sand hardness is 7, able to withstand minor scratches). 

Color Customization

Color masterbatches are categorized by plastic type (PE carrier for PP, PC carrier for PC), with an addition amount of 2%-5%; adding too much affects strength.

For example, Mares' fluorescent fins use an orange masterbatch (3% concentration), with a color difference ΔE <1.5 (barely noticeable to the human eye), and a 40% higher brightness in sunlight compared to standard colors.

PADI and Scubapro's collaborative commemorative mask uses PADI blue (Pantone 2945C) for the frame, adding pearlescent powder (0.5% content) to the masterbatch, giving a shimmering effect under different lighting.

Cressi's children's fins are even more exaggerated, using 12 macaron colors (pink, green, yellow), and mixing 0.3% anti-UV agent into the masterbatch to prevent fading.

Before warehousing, the Lab values (color coordinates) of each batch of masterbatch are measured and compared with the standard color plate; batches with a deviation exceeding ΔE=2 are rejected.

When changing colors in the mold, a dedicated cleaning agent (such as DuPont's Ultraclean) is used, cleaning 3 injection cycles to avoid color mixing; the cleaning time is only 10 minutes, half the time required for silicone color changes.

With this process, plastic gear can be shipped from raw material to finished product in as little as two days (silicone takes a week), and costs are kept low, which explains why 65% of the entry-level market in Europe and America is plastic.

Usage Restrictions and Improvements

Rigid Material

For example, a Cressi ABS frame mask has a frame hardness of Shore D78; after wearing it for half an hour, the pressure on the cheeks can reach 15kPa (silicone models are generally <10kPa), and beginners often complain of "feeling pinched."

Fins are the same; the edges of hard plastic foot pockets (such as a certain entry-level EVA+PP mixed foot pocket) lack curvature, and when the toes are bent to kick, the pressure on the joints exceeds 20kPa, causing soreness after 1 hour of swimming.

Cressi later attached a 2mm thick liquid silicone strip (Shore A 50) to the inner side of the ABS frame, reducing the pressure to 9kPa, and user satisfaction rose from 62% to 89% in surveys.

Another improvement uses modified PP; for instance, Scubapro's Flex Frame mask adds 15% elastomer to the PP, reducing the hardness to Shore D 65, increasing flexibility by 25% compared to ordinary PP, and providing better adaptability to different face shapes.

Fin foot pockets are modified with EVA wrapping (3mm thick) and rounded edges, distributing pressure evenly and preventing chafing during long periods of use.

UV Exposure

European and American outdoor tests show that PP without added anti-UV agents used for 1 year on the Florida coast has a yellowing index ΔYI=6 (ISO 4892-2 standard, ΔYI＞3 is visible yellowing to the naked eye), and tensile strength drops from 30MPa to 22MPa (a 27% decrease), making it easy to crack when bent.

PC plastic is slightly better, with an annual yellowing ΔYI=3, but brittleness increases, and notched impact strength drops from 60kJ/m² to 45kJ/m² (a 25% decrease).

For example, Aqua Lung's plastic gear mixes 1% UV-328 (benzotriazole stabilizer) into the raw material; after 2 years of exposure on the California coast, ΔYI is <2.5, and tensile strength retention is >88%.

Mares' high-end models are even more robust, adding 2% HALS (Hindered Amine Light Stabilizers), extending the anti-aging time to 3 years, with ΔYI only reaching 1.8.

Ordinary Plastic Impact Resistance

PP's notched impact strength is only 5-8kJ/m² (silicone can be >20kJ/m²).

The lab used a falling weight test (a 1kg weight dropped from 0.5 meters onto a plastic lens); the PP lens cracked, while the PC lens did not, but PC is 30% more expensive, so it's rarely used in entry-level models.

Improvements are made in two steps: Scubapro's Pro Flex fin uses a PC/ABS alloy for the blade (impact strength 18kJ/m²), 1 time higher than pure ABS, and does not crack in the 0.5-meter falling weight test.

Cressi's carbon fiber reinforced plastic fins are more extreme, embedding 10% carbon fiber in the blade (unidirectional alignment), increasing stiffness by 40%, and impact strength to 25kJ/m², but the price doubles.

There's also surface hardening treatment, such as spraying a 0.2mm thick polyurethane coating on the TUSA mask frame, increasing Mohs hardness from 2 to 4, so sand won't leave marks.

Hybrid Material Upgrades

The most common is a plastic body + silicone contact parts. For example, US Divers' Oceanic mask uses a PP frame (30 grams, density 0.91g/cm³) and a liquid silicone skirt (Shore A 55); the sealing pressure can reach -25mbar (negative pressure seal, no water leakage), which is much more reliable than an all-plastic skirt (-10mbar).

The head strap is also silicone, 25mm wide, dispersing pressure, so it doesn't constrict the head.

Mares' Avanti Quattro fin blade is Nylon 66 + 15% glass fiber (density 1.3g/cm³), 50% stiffer than pure PP, preventing deformation when kicking, and increasing propulsion efficiency by 18% (lab water tank test, 2N more thrust at 1m/s swimming speed).

The foot pocket uses EVA foam (density 0.2g/cm³), which provides better cushioning than hard plastic, preventing discomfort when stepping on seabed rocks.

There are also plastic + metal combinations, such as high-end snorkel regulator valves, which use stainless steel springs (corrosion resistance level 316L) with a plastic valve body, making switching smoother and preventing jamming after 5 years of use.

European dive shop statistics show that the annual damage rate of plastic + silicone masks is 40% lower than all-plastic ones (mainly fewer breakages due to customer discomfort from pressure), and repair costs are reduced by 25%.