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How to Remediate Heavy Surface Mold -- MSI-4 Zones

Heavy surface mold can be pesky to remediate. The past few weeks we have been reviewing the best ways to remediate mold based on it's severity. In this post, we will be covering how to remediate a MSI-4 zone which is characterized by heavy and consistent mold with sporafic pigmentation staining.

Mold Severity Indexing is a tool that helps contractors define the mold levels of a zone within a property properly and efficiently. It is based off of the conditions defined by the IICRC but goes more in depth so the best application can be practiced to treat the zone and yield the best results!

Spectrum of MSIs:

MSI-4 Remediation

When covering MSI-3 we introduced our recommended REACT | EXTRACT method. We recommended this for MSI-4 zones as well with a re-reaction and re-extraction.

REACT | EXTRACT is a system of remediation where the neutralization between two proprietary products, OxyPrep and OxyPar LR, followed by vacuum extraction, result in superior remediation. Depending on the severity of the situation, REACT | EXTRACT methods may be repeated; for MSI 4, they are just implemented twice. It is a superior method to remove deep soil loads and disinfect the area. This process is based on information and recommendations from the industry standard, IICRC S-520.

Also, we have created materials to help you walk through these steps. These resources can be found under the Learn tab, on the Procedures page.

The first tool is an in-depth Step-by-Step guide. It will take you through what materials are needed to complete the job, how you should prepare, how to scale what product you will need, and use instructions. This guide helps you think through how much product you may need to order and what small things will leave your customer most satisfied with their results.

The second tool we have created is a Cocktail Card. This is a resource that you can quickly pull up on the job and remind yourself of some steps that need to take place or materials that will be needed. It also offers some helpful tips so you can ensure you preforming the best practices.

Highlighted Products for MSI-4 Zone Remediation:


OxyPrep is a ready-to-use, water-based, instant mold stain remover. It eliminates the messy scrubbing, sanding and/or media blasting that can also lead to cross-contamination issues. OxyPrep is stabilized to prevent deterioration and shelf stability issues as well as to maximize safety for the user.

OxyPar LR

Oxypar LR is a ready-to-use hydrogen peroxide cleaner that immediately penetrates, lifts and suspends soil loads and brightens surfaces for a completely clean substrate. Can be used on wood, composite materials, concrete, brick, stone, grout, masonry, gypsum, and painted surfaces.

This product will foam up to show you where the soil load is so you can wipe it clean for a clean surface.

Dutrion 20 g Tabs

Dutrion 20 gram tabs are a versatile, easy-to-use chlorine dioxide solution! All you do is drop the tablet into water to yield the solution type you are looking for and it is ready to go. Also, it is small, light-weight, and easy to transport to your job site.

Dutrion can be used to disinfection, cleaning, and more. We recommend using it to remediate mold zones.

BTM Sprayer

Our Enviroguard BTM Sprayer system aids in effectively applying product through a pressurized spray job. This helps to create consistency and efficiency while also eliminating product waste by having better control over your product.

Also, it is a dual pump system, so you can have two products ready to go at a time.


SorbAssist was formulated from a blend of essential oils for safety but with the performance to mask the most pungent chemical odors. It can be diluted into cleaners, stain removers and disinfectants, and it can be diluted and used alone to freshen spaces after jobs.

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