Abstract
The Full Face Snorkel Mask (FFSM) is one of the most disruptive innovations in the snorkeling equipment sector in recent years. Unlike traditional masks that cover only the eyes and nose, the full face snorkel mask covers the entire face and integrates the snorkel into the mask body, allowing users to breathe naturally through their nose. This article starts from the unique design principles of the full face snorkel mask, systematically elaborating on its core design elements such as the two chamber structure, intake exhaust separation system, and dry top float valve mechanism. It provides an in depth analysis of the material selection basis for polycarbonate (PC) lenses and liquid silicone rubber (LSR) skirts, as well as the integral molding (overmolding) process path. Combined with specialized testing standards—including CO re inhalation testing, field of vision evaluation, and seal performance tests—this paper constructs a complete technical framework for the full face snorkel mask, from design and manufacturing to quality control.
1. Introduction
Traditional snorkeling masks cover only the eyes and nose, requiring the user to breathe through a mouth held snorkel. Although this design is well established, it has clear limitations—mouth breathing is unnatural for beginners and can easily cause anxiety and breathing difficulties. The advent of the full face snorkel mask fundamentally changes this situation: it covers the entire face and integrates the snorkel at the top of the mask body, enabling users to breathe naturally through their nose, just as they would on land.
However, the design complexity of full face snorkel masks far exceeds that of traditional products. It must not only solve the problems of clear vision and facial sealing, but also address a more challenging engineering issue—the separation of inhaled and exhaled breathing gases. If the inhaled air mixes with the exhaled waste gas inside the mask, the user will repeatedly breathe in their own exhaled carbon dioxide, leading to headaches, breathing difficulties, or even loss of consciousness. For this reason, the design and manufacturing of full face snorkel masks involve the integrated application of multiple disciplines, including fluid dynamics, ergonomics, and polymer material molding. Although the EN 16805:2015 standard specifies requirements and test methods for diving masks, it clearly states that it does not cover full face masks or oro nasal masks. Testing of full face snorkel masks more often refers to the CO concentration related clauses of EN 136:1998 (Respiratory protective devices standard).
2. Design Principles and Structural Features
2.1 Two Chamber Structure
The most central structural feature of the full face snorkel mask is the partitioning of the internal cavity. The interior of the mask is usually divided into two chambers: an upper chamber (viewing chamber) and a lower chamber (breathing chamber).
The upper chamber is located in the eye area and communicates with the intake airway of the snorkel. Fresh air entering from the snorkel first fills the upper chamber and then passes through a one way intake valve provided on a partition to enter the lower chamber. The lower chamber covers the mouth and nose area and is the space where the user actually breathes. The partition (also called the nose bridge seal) fits over the user's nose bridge and effectively isolates the two chambers on the facial side.
The engineering significance of this two level structure is to separate the viewing area from the breathing area. Fresh air flows across the transparent lens area of the upper chamber, carrying away moisture from the inner surface of the lens, thus providing active anti fogging; meanwhile, exhaled waste gas is discharged directly through an independent exhaust passage and does not mix with the fresh air in the upper chamber.
2.2 Intake Exhaust Separation System
Intake exhaust separation is the most critical element in the design of full face snorkel masks. The core mechanism is as follows:
Intake path: Ambient air enters through the air inlet at the top of the snorkel, travels down the snorkel into the upper chamber of the mask, and then passes through the one way intake valve into the lower chamber for inhalation by the user.
Exhaust path: The waste gas exhaled by the user exits the lower chamber through an independent exhaust passage. The exhaust passage is usually arranged along the perimeter of the mask and eventually merges into the exhaust duct of the snorkel to be discharged to the outside.
A one way valve system is installed between the intake and exhaust paths to ensure that airflow moves only in the correct direction. The intake valve allows air to flow from the upper chamber to the lower chamber but closes during exhalation to prevent waste gas from flowing back into the upper chamber. The exhaust passage is also equipped with a one way valve to ensure that waste gas only exits and does not enter.
Professional manufacturers such as Khroom emphasise that the design principle of intake exhaust separation is derived from respiratory protection technology, using multi chamber systems and safety valves to prevent exhaled air from being re inhaled.
2.3 Dry Top Snorkel and Float Valve Mechanism
The snorkel at the top of the full face snorkel mask typically adopts a dry top design, equipped with a float valve mechanism at its upper end. When the snorkel is submerged, the float rises and pushes a sealing element to close the air inlet, preventing water from entering the mask. This design means that even if the user's head is covered by waves while surface snorkeling, water will not flood into the mask, greatly enhancing safety and comfort.
2.4 Purge Valve and Ear Pressure Equalisation
A purge valve is usually provided at the bottom of the lower chamber of the full face snorkel mask to drain any small amount of water that may accidentally enter the mask. The purge valve is generally a one way structure, allowing water to be expelled from the inside but preventing water from seeping in from the outside.
For users who need to dive down, some full face snorkel masks are equipped with a flexible nose pinch structure in the nose bridge area, allowing the user to equalise ear pressure by pressing the nose from the outside. This design accommodates both the sealing requirements of full face coverage and the practical needs of diving activities.
2.5 Ergonomics and Computational Fluid Dynamics
The design of modern full face snorkel masks has shifted from experience based to data driven. Companies such as Bluelab, when developing the Seaview series, introduced Computational Fluid Dynamics (CFD) into the design process, using simulation to analyse the airflow and gas mixing inside the mask to ensure that the airflow maintains low pressure and low CO concentration.
Ergonomic considerations are equally in depth. Design teams use headform data and anthropometric parameters to find the optimal balance between sealing and comfort, reducing the pressure and discomfort exerted on the face. The design of the facial contact contour directly affects sealing performance—the pressure distribution of the sealing lip needs to be uniform: not too loose to cause leakage, nor too tight to cause compression.
3. Material Selection
3.1 Lens Material: Polycarbonate (PC)
The lenses of full face snorkel masks (often referred to as the "face window" or "transparent visor") are almost exclusively manufactured from polycarbonate (PC) . The key advantages of PC material include:
High light transmittance: High quality PC substrates can achieve light transmittance of over 92%.
Extremely high impact resistance: Meets the stringent impact performance requirements for diving mask lenses.
Low specific gravity: Significantly reduces overall weight compared to glass lenses.
Injection mouldability: Enables precise manufacturing of large area, complex curvature lens shapes.
Ease of overmolding: PC exhibits good adhesion to LSR silicone during in mould overmolding.
The lens area of a full face snorkel mask is far larger than that of a traditional mask, and some products even feature a 180° panoramic field of view design, which imposes higher demands on optical precision and moulding processes.
3.2 Skirt and Sealing Material: Liquid Silicone Rubber (LSR)
Liquid Silicone Rubber (LSR) is the preferred material for the skirt and facial seals of full face snorkel masks. The properties of LSR make it an ideal choice:
Excellent flexibility and resilience: Conforms closely to different facial contours; high quality mask skirts typically require a Shore A hardness between 30 and 40 for optimal facial sealing.
Chemical inertness: Resistant to seawater corrosion, UV radiation, and chlorine.
Biocompatibility: Food grade LSR has passed both FDA and LFGB certifications and is non allergenic on facial contact.
High precision moulding: LSR liquid injection moulding can achieve accuracy of ±0.01 mm.
Odourless and fluorescent free: Suitable for prolonged facial contact.
3.3 Rigid Structural Materials
Rigid structural components such as the main frame and the snorkel body are typically manufactured from engineering plastics (e.g., PP, PC, or ABS). These materials provide the necessary structural rigidity and connection strength while keeping the overall weight light.
4. Manufacturing Process
The manufacturing of full face snorkel masks involves multiple precision process stages—from lens injection moulding, skirt forming, and snorkel fabrication to final assembly—each of which has a decisive impact on product quality.
4.1 PC Lens Injection Moulding
Injection moulding of large area PC lenses is the first critical step in the production of full face snorkel masks. The process flow is as follows:
(1) Raw material drying: PC material must be thoroughly dried before injection moulding (typically 4 10 hours) to remove moisture, preventing defects such as dull colour, internal bubbles, and carbonised spots in the finished product.
(2) Injection moulding: During injection, parameters such as melt temperature (220–260°C), injection pressure (70–140 MPa), and mould temperature (approx. 90°C) must be strictly controlled. Large area lenses demand extremely high filling uniformity; the location and number of gates, as well as the venting system design, directly affect the optical quality of the lens.
(3) Annealing: After moulding, the lenses undergo annealing (usually held at 75–95°C for 3 5 hours) to relieve internal stresses and stabilise optical performance.
4.2 LSR Skirt Liquid Injection Moulding (LIM)
LSR skirts are manufactured using the Liquid Injection Moulding (LIM) process. LSR is a two component liquid silicone that is mixed in precise proportions in a dedicated injection machine, then injected into the mould cavity, where cross linking and vulcanisation take place under heat.
Special attention must be paid to the mould design for LSR skirts:
Venting system: Ensures complete evacuation of air from the cavity to avoid bubbles or short shots.
Temperature control: LSR vulcanisation temperatures typically range from 150–200°C, and mould temperature must be precisely regulated.
Parting line design: The skirt has a complex 3D curved surface; the choice of parting line directly influences the appearance of the part and the ease of demoulding.
4.3 Integral Moulding (Overmolding) Process
The core manufacturing technology for full face snorkel masks is the integral moulding of the lens and skirt (also known as overmolding or co injection moulding). This process simplifies the traditional three piece structure of "lens frame skirt" into a single integrated "lens skirt" unit.
Process steps:
(1) PC lens pre positioning: The already moulded PC lens is precisely placed into the designated position of the secondary mould. The edge of the lens is usually designed with micro undercuts to enhance mechanical interlocking with the silicone.
(2) Interface pretreatment: To ensure strong adhesion between PC and LSR, the lens edge must be pretreated—either by applying a specialised primer or by roughening the surface to increase interfacial bond strength.
(3) Mould closing and LSR injection: After the lens is positioned, the injection machine injects the liquid silicone rubber into the cavity. During vulcanisation, the silicone bonds with the lens edge at the molecular level.
(4) Vulcanisation and demoulding: After the LSR has completed cross linking and vulcanisation in the mould, the lens and skirt are firmly bonded as one, forming a complete lens skirt unit.
The advantages of this integral moulding process are extremely significant:
Elimination of seams: Completely removes the adhesive and mechanical seams of traditional structures, structurally eliminating the risk of water leakage.
Wider field of view: The frameless design removes obstruction of the line of sight by the frame.
Lightweight construction: Eliminates the independent plastic frame.
High production efficiency: The joining is completed in a single moulding step, eliminating secondary assembly.
High end products from brands such as Beuchat, TUSA, and Aqualung have all adopted this technological approach.
4.4 Snorkel Fabrication and Integration
The snorkel of a full face snorkel mask is usually integrated with the mask body, becoming an inseparable part of the mask. Snorkel fabrication involves:
(1) Tube body moulding: The snorkel main body (typically made of rigid plastic) is manufactured by injection moulding, with separate internal intake and exhaust channels.
(2) Float valve assembly: The float valve mechanism at the top of the snorkel includes components such as the float, float seal, and float valve cover, which require precise assembly to ensure reliable sealing when submerged.
(3) Connection and sealing: The snorkel can be connected to the mask body either by integral moulding (forming the snorkel structure directly during mask moulding) or through a rigid connector with sealing.
4.5 Anti Fog Treatment
Anti fog treatment on the inner surface of the lens is a critical step in the manufacture of full face snorkel masks. The anti fog strategy for full face snorkel masks is a dual guarantee of structural anti fog and coating anti fog:
Structural anti fog: Through the intake exhaust separation design, dry fresh air flows across the inner surface of the lens, actively carrying away moisture.
Coating anti fog: A super hydrophilic anti fog coating is applied to the inner lens surface, causing water vapour to spread evenly into a continuous water film rather than condensing into droplets.
Dual lens structure: Some products adopt a double lens design, with an insulating air layer in between to reduce temperature differences that cause fogging.
4.6 Assembly and Final Integration
The integral moulding process greatly simplifies the assembly process, but full face snorkel masks still require the following assembly operations:
Installation of one way valves (intake and exhaust valves)
Assembly of the purge valve
Installation of head straps and buckles
Assembly of the snorkel float valve (not required separately if integrally designed)
In some designs, a support device is integrally provided on the rigid lens portion to reinforce the rigidity of soft functional components (such as one way valves and exhaust passages), ensuring precise and reliable actuation.
5. Quality Inspection and Standards
Quality inspection of full face snorkel masks is more stringent and comprehensive than that of traditional masks, with special requirements regarding respiratory safety.
5.1 CO Re Inhalation Test (Core Specialised Test)
The CO re inhalation test is the most critical safety test for full face snorkel masks. Because the full face mask covers the mouth and nose, failure of the intake exhaust separation design could cause the user to repeatedly inhale their own exhaled CO .
The test method generally follows EN 136:1998, Clause 7.18 (Respiratory protective devices standard) and is performed by independent laboratories such as TüV Rheinland, DEKRA, and SGS. During the test, the user wears the mask at different breathing frequencies, and instruments measure the CO concentration in the inhaled air inside the mask in real time. Qualified products must ensure that the CO concentration remains within the safe range at all times.
5.2 Field of Vision Test
Field of vision evaluation of full face snorkel masks uses a standard headform system to measure the maximum visible angle in the horizontal and vertical directions. The goal of the large area lens design is to provide the widest possible underwater field of view; some products claim a 180° panoramic view.
5.3 Seal Performance Testing
Seal performance testing includes:
Static leakage test: The mask is fitted onto a standard headform, a specified negative pressure is applied, and the pressure change is monitored to assess sealing capability.
Dynamic leakage test: Simulates sealing performance under different facial contours and wearing forces.
Long term sealing reliability: Simulates changes in sealing performance after prolonged use.
5.4 Breathing Resistance Test
Measures the breathing resistance inside the mask at different breathing frequencies to ensure that breathing is smooth and effortless. The breathing channel design must be sufficiently spacious to reduce resistance.
5.5 Impact Resistance and Mechanical Performance Testing
Drop ball impact test: A steel ball of specified mass is dropped from a specified height onto the lens; the lens must not crack.
Head strap and buckle durability test: Thousands of cyclic tensile tests are performed.
Valve function test: Verifies the reliable actuation of one way valves at different breathing frequencies.
5.6 Material Safety and Biocompatibility Testing
Chemical substance extraction testing (heavy metals, phthalates, polycyclic aromatic hydrocarbons, etc.)
Skin irritation and sensitisation tests
Evaluation of material property changes after prolonged immersion
6. Conclusion
As a revolutionary product in the snorkeling equipment field, the design and manufacturing of the full face snorkel mask represent a deep integration of optical engineering, fluid dynamics, ergonomics, and polymer material moulding technology. From the ingenious design of the two chamber structure and intake exhaust separation system to the innovative application of integral moulding of PC lenses and LSR skirts, every link embodies engineering wisdom and a high sense of responsibility for user safety.
Currently, the manufacturing of full face snorkel masks is continuously evolving towards higher integration, lower breathing resistance, and more reliable sealing. Advanced tools such as Computational Fluid Dynamics simulation and 3D printing rapid prototyping are accelerating product iteration. At the same time, as consumer safety awareness increases and testing standards become more comprehensive, the full face snorkel mask industry is shifting from "marketing driven" to "engineering driven"—only products that truly withstand rigorous testing by independent laboratories can earn consumer trust in the market.
In the future, full face snorkel masks will further optimise CO evacuation efficiency, expand the field of view, and enhance wearing comfort, while maintaining the natural breathing experience, thereby providing more snorkeling enthusiasts with a safe and enjoyable underwater exploration experience.
WAVE China is a full face diving masks manufacturer. If you are interested in full face diving masks, please contact us.
