How to perform a Visual-Seal-Check (VSC)?

New user seal check of TOTOBOBO mask predicts fit-test success rate

Totobobo masks are able to fit a wide range of large and small faces. However, it is not possible to claim that it will always seal your face perfectly. Sometimes it may require adjustment of the strap and the position of the mask to improve the seal. Sometimes trimming down the mask to a smaller size may help.

The purpose of a Visual-Seal-Check is to provide a fast and reliable method to evaluate the face seal, without the need of fit-test equipment.

User-seal-check of a normal respirator (e.g. N95 mask) involves the steps of cupping the filter area with hands, forcefully inhaling and/or exhaling to sense if there is air-leak. Such method relies on the user’s ability to feel the air movement around the leak area. Several studies have shown that this method is not reliable.

The Totobobo Visual-Seal-Check (VSC) method (patented) is facilitated by a very fine texture moulded on the inside of the transparent mask. In normal condition, the surface is dry and it appears as semi-transparent. The same surface turns transparent if there is water stuck on the surface. Even a tiny amount of water trapped between the mask and the face will make the surface change from semi-transparent to complete transparent.

To do a simple Visual-Seal-Check, you apply a little moisture on your face, than put the mask on. Observe the edge of the mask. Where it is completely transparent, there is a good seal. Where it is semi-transparent, there is no seal. It is considered as a good overall seal if there is a continuous transparent band circle around the nose and mouth.

Our user test using a TSI PortaCount system in a hospital, the gold standard of respirator fit test, shows there is a strong correlation (90%+) between the Visual-Seal-Check (VSC) and the standard fit-test results. In other words, it is possible to predict if the mask will pass or fail the gold standard fit-test by performing a TOTOBOBO VSC. This is particular useful for people who don’t have access to a proper fit-test system.

Milky surface indicates the face seal leak location

Milky surface indicates the face seal leak location

Transparent surface indicates good face seal of Totobobo mask

Transparent surface indicates good face seal of Totobobo mask

7 thoughts on “How to perform a Visual-Seal-Check (VSC)?”

  1. Pingback: Incense smoke demo
    1. Hi Rohan, the seal will naturally become tighter as you inhale due to negative pressure inside the mask. The seal will break more easily when you exhale- due to higher pressure inside the mask. By the color of the used filter, you can tell how much dirt the mask has helped, even it may not be a perfect seal. However, for protection against deadly viruses like SARS or bird flu, it is extrememly important to make sure the seal is good.

Leave a Reply

Your email address will not be published. Required fields are marked *