How to perform a seal check with the water mark method?

The protection of a respiratory mask depends on two factors:
1. How good is the air filter and
2. How well the mask is able to seal your face, such that the air you breathe in must go through the filters.

The filters can be tested by reputable laboratory where certified reports are produced. We sent filters to Nelson Labs in USA and the results are published.
However, it is not at all easy for individual user to determine if the mask is really fitting the face completely without any gaps. Totobobo is the only mask in the market provides a simple method, or the “Water Mark check”, to let users ensure the face seal.

Water mark shows poor and good seal before and after ReShape of Totobobo mask.

Water mark shows poor and good seal before and after ReShape of Totobobo mask.

The frost edge of the mask changes to transparent when it touches wet skin. This is called the “water mark”. Followings show a step by step approach to check the seal with the water mark:
– Apply a thin layer of water on the user’s face with cotton wool, especially around the nose bridge and chin area.
– Don the mask and carefully examine the water mark.
– Check if the water mark form a complete, continuous loop encircling the nose, mouth and under the chin, that indicates the mask is making a good seal around your face. The mask is now ready for use.
– If there are patch(s) of frost area breaking up the water-mark-loop, that indicates where the seal breaks and you may need to adjust the mask to improve the seal. There are several things you can do, such as:
1) Adjust the position of the mask. (shift it up and down to find the optimal position)
2) Adjust the tension of the elastic straps (it should be firm, but not too tight)
3) ReShape the mask (use 70°C water or hair dryer, but don’t overheat!)
4) Cut the mask smaller (only when it is really necessary!)

Your mask is ready to give you the best protection when you have a good seal. Do use the water mark method to double check the seal.

Totobobo demo in Beijing and Shanghai

Swanport cafe in Soho Galaxy at Chaoyang, Beijing

Swanport cafe in Soho Galaxy at Chaoyang, Beijing

Muren of Totobobo Tmall share a presentation about PM2.5

Muren of Totobobo Tmall share a presentation about PM2.5

Francis shared his story about Totobobo mask

Francis shared his story about Totobobo mask, Robin from Totobobo Tmall is providing realtime translation

2014-09-16 Swanport Cafe, Chaoyang District, Beijing

The demo in Beijing was a great success on a Tuesday evening, thanks to Robin and Muren from Totobobo Beijing and the helpful staff from Swan Port Cafe. The session started off with a brief introduction of PM2.5 by Muren, he explained what PM2.5 is, and how it affects our health. Francis, the designer of Totobobo mask, shared how he came up with the idea of a customizable and reusable respirator mask out of the SARS crisis in 2003. The fit-test demo started after a short tea break.

What is “Fit-test”? Why it is important?

Fit-testing is a procedure to determine if a tight seal can be achieved when the user don a respirator mask. This is important because the quality of the seal affects the overall protection against PM2.5 and other airborne contamination. In fact, the NIOSH N95 standard requires a proper fit-test to be conducted before anyone starts using a respirator for the first time. During the fit-test, a particle counting instrument is used to accurately measure respirator fit by comparing the particle concentration in the surrounding air with the particle concentration inside the respirator. The ratio of these concentrations is called the Fit-factor (FF). For N95 mask, a minimum Fit-factor of 100 is required in order to pass the fit test.

Fit factor formular

Fit factor formular

TSI Portacount is the best fit-testing machine in the world. (US Army recently purchased 65 sets of the same TSI Portacount fit-tester

The working principle of the PortaCount 8083 is straight forward: there are two flexible tubes coming out of the machine, one is to draw the air and measure the concentration of particles inside the mask. The second tube is open ended and is used to measure the particle concentration in the surrounding area. The PortaCount fit-tester calculates the particle concentration inside and outside of the mask and report the ratio, or the Fit-factor, in realtime. The higher the Fit-factor, the better is the protection effect of the mask. With the Portacount machine, Francis was able to demonstrate quantitatively how the quality of the seal and the filters can have a great impact on the protection effectiveness of a respirator.

Preparing for the test

Francis exchange ideas with the VIPs.

Francis exchange ideas with the VIPs.

Before the fit-test, a “Daily check” on the machine was performed to assure that the ambience air quality is suitable for the test and the machine is in proper operation condition. Amongst the audience, there were members from the China Consumer Association (中国消费者协会), National labor supplies Quality Supervision and Inspection Center (Beijing) 国家劳保用品质量监督检验中心(北京), Austria Embassy, TimeOut Beijing, and members of the public to monitor the entire process of the fit-test demo.

Fit test demo with PortaCount professional fit-tester

Faye testing Totobobo mask

Faye testing Totobobo mask

The perfect shape for Faye

The perfect shape for Faye

Fit-factor is only 3.3, the result of the cosmetic cotton pad is not convincing

Fit-factor is only 3.3, the result of the cosmetic cotton pad is not convincing

The first Fit-test of Totobobo mask was performed on Faye, a Chinese lady with a slender face shape. Francis first tested a pair of “fake filters” made of cosmetic cotton pad. The “fake filters” looks nearly the same as the original, but the resulting Fit-Factor is only 3.3 which means on a day with AQI 500, the cotton pad can ideally bring it down to 150, just not good enough. After changing into a pair of F96 filters, the Fit-factor shoot up to 150+. In AQI 500 day, ideally it can bring it down to 4-, better than the air you will get in Switzerland!

The Fit-factor shoot up to 150+ after changing into a pair of F96 filters

The Fit-factor shoot up to 150+ after changing into a pair of F96 filters

The second participant was a young girl (Guo Yao) with a fuller face. Francis first conduct the test with the same Totobobo mask without modification. The water-mark-method shown that the seal was not perfect and the initial result was relatively low (below 50). However, after Reshape the mask with a hair-dryer and after a good water-mark is obtained, the Fit-factor reported by the Portacount machine come up to 200+.

The perfect shape to fit  Guo Yao after ReShaping the mask

The perfect shape to fit Guo Yao after ReShaping the mask

Guo Yao received a new Totobobo mask from Sharon, Managing Director of Totobobo mask.

Guo Yao received a new Totobobo mask from Sharon, Managing Director of Totobobo mask.

Francis using the "Water-mark" method to predict the fitting of the mask

Francis using the “Water-mark” method to predict the fitting of the mask

Francis also demonstrated the effect of good and poor seal, by the “water mark method”. He applied a bit of water around the nose bridge area. When the matt color mask surface touching the wet skin, it changes to transparent (water-mark).

Barbara testing Totobobo mask

Barbara testing Totobobo mask

The third participant was Barbara Grosse from the Austria Embassy. It took Francis few rounds of ReShaping the mask in order to obtain a good water-mark seal. The final Fit-factor was also in the range of 150~200+. All three ladies passed with a clear margin from the minimum requirement of 100 (for N95 mask).

Fit-test demo based on only three users is obviously not statistically sound. However, we have done this nearly a hundred times privately and this is the first time we perform the fit-test in front of a public group.

After Beijing, we went to Shanghai ArtBike to conduct another fit-test demo with their customers. We came to similar observation as in Beijing.

Fit-test at ArtBike, Shanghai

Fit-test at ArtBike, Shanghai


Some interesting facts we can draw from all the fit-tests:

1. Totobobo mask can be ReShaped to fit a wide range of face shapes.

  • The same Totobobo mask was used through out the fitting on all three ladies, with significantly different face shapes and all managed to obtain high Fit-factors above 150.
  • Many more fit-tests on different users shows the ReShape function can be applied to a wide range of users.

2. The “Water mark” method is reliable to help ensure face fit and protection.

  • There was a strong correlation between the water-mark-method and the PortaCount results
  • When the water-mark method showed the seal was not perfect, the corresponding Fit-factor dropped  to below 50 and sometimes down to single digit value.
  • When a clear water mark was formed around the nose bridge and the face, the corresponding Fit-factor shot up to 150+

3. Overall protection against PM2.5 require good quality filter AND a good face-mask seal

  • When cosmetic cotton pad is used in place of the Totobobo filters, the Fit-factor dropped to only 3.3.
  • When the water-mark shows there is a leak between the mask and the face, the Fit-factor dropped to below 50 and sometime single digit.
  • The resulting Fit-factor is consistently good (150+) when Totobobo filter is used and the water mark result is positive.

Above points 1&2 are the strengths and the weaknesses of Totobobo mask, ReShape (and cutting) makes Totobobo mask the most versatile solution to fit a wide range of users, including children and adult. But ReShaping and cutting the mask is more complicated than bending a metal nose clip. With the “Water mark” fit-test method, you can be sure that when the water mark seal up your nose and mouth, the mask is giving you high level of protection. In contrary, ensuring face-seal is much more tricky for many popular masks on the market, as a detail research concluded by Tongji Medical College (Huazhong University of Science and Technology, Wuhan, China) suggested: Fitting Characteristics of N95 Filtering-Facepiece Respirators Used Widely in China . 8 out of 10 popular mask can only fit less than 10% of the 54 Chinese test subjects.

On the other hand, these two features are the limiting factors for Totobobo mask to gain certification approval. It is confirmed that the current testing protocol does not allow  mask samples to be reshaped,  cut, or perform a water-mark check before the fit. These may well be the reasons why Totobobo mask did not perform well in the published review of 37 masks by Chinese Consumer Association earlier this year. Obtaining the certification is an important step for marketing purposes, but for now we put our focus on the practical protection that can be measured by the professional fit-testing machine (PortaCount 8083).


Related links:

Beijing TimeOut

Totobobo Fit-test demo on Weibo (1)

Totobobo Fit-test demo on Weibo (2)

Testing Totobobo mask with Portacount 8083 (video of entire process)

How to ReShape Totobobo mask?


How to ReShape your Totobobo Mask for a perfect fit?

Heat moulded Totobobo mask
Heat moulded Totobobo mask

[Click here if you cannot view youtube from China]


Some of our user’s feedback stated that it would be great to add a nose clip to the Totobobo Mask, especially for people with a prominent nose. These users are experiencing small gaps between the mask and their nose’s bridge. However, a nose clip is not a reliable solution in the long run for reusable masks. Prototype testings have showed that the clip breaks or loses it’s rigidity after repetitive bending and will break eventually.

The following video shows how to re-mould the Totobobo Mask, using hot and cold water. The hot water helps to soften the body of the mask, while the cold water helps to harden the mask after reshaping it to the desired shape. This method can be done over and over again, there fore, making it a more reliable solution.

The heat treatment can be applied to any parts of the mask (e.g. the chin), not only the nose area. The possibilities are limitless. You may need to try moulding the mask several times to achieve the best fit.


Moulding feature further enhances protection and comfort for the user.

Better face fitment = lesser gaps = better protection

PM2.5, a very fine airborne particle, is smaller than 2.5 microns which can be inhaled and travel deeply into our lungs, which will then enter our bloodstream. These particles causes micro inflammation and hardens our blood vessels. Recent studies have showed that the PM2.5 not only triggers diseases in our lungs and other respiratory organs, but also triggers cardiovascular diseases and strokes. Common surgical masks or even a poor fitting N95 mask won’t be of much help due to the cunningness of the PM2.5. Ensuring a secured face fit is the first fundamental step towards respiratory protection.

Totobobo Mask have three key features to aid you in obtaining a optimal face fit.

  1. Sizing : Totobobo Mask is the first and only mask that allows its user to cut to fit. You don’t have to risk over cutting the mask. Download this template to test the size using a paper dummy first, before proceeding to cut the actual mask.
  2. Fine tuning with heat moulding : The heat moulding process makes it possible for the user to fine tune the fitment of the mask. Small gaps around the nose or under the chin? No worries! Just re-mould the mask and you’ll be able to eliminate, or at the least, minimize these gaps. You can re-do this step as many times as you like! Remember to not use boiling to re-mould the mask, otherwise you’ll risk destroying the mask. Use warm to hot water around 80C instead.

Another point to note, a small gap occurring during exhalation does not affect the effectiveness of the protection, in fact, it may be beneficial as it helps to release exhaust gases quickly. What you need to check is whether the seal is closed tightly when you inhale, due to the negative pressure while inhaling. Ideally, you should adjust the straps so there there are small gaps to speed up exhaling and feeling comfortable at the same time.

    Visual Seal Check (VSC) : Using the transparent property of the Totobobo Mask, you can check if the mask is touching the areas below the chin, forming a good deal. If the seal is not optimal, you may fine tune the cutting and moulding of the mask, or simple adjusting the position and tension of the strap to get a better fit.

Wearing Comfort

If a mask is not comfortable to wear, the user will use it less often, so the chances of it being functional is generally lesser as well.

The heat moulding adjustment allows the mask to be re adjusted to fit your face profile closely. A good fit is beneficial as it not only provides a good seal, but you’ll also feel more comfortable wearing it and also not forgetting, you can loosen the tension on the straps as well. During exhalation, the internal pressure pushes the mask and forces the seal to be broken, releasing the air quickly. During inhalation, the process creates a “sucking” motion due to the negative pressure, which closes up the gaps, forcing air to enter only by the filters. The Totobobo mask functions like a one-way valve, without it being a valve physically. Some users described it as “The mask is breathing with me.”

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