Zinsser Mold Killing Primer, Did you read the label?
As a Mold Assessor I come across the question of whether Zinsser is an acceptable encapsulate? Firstly, Zinsser is not an encapsulate material at all. It is a primer, part of a two step system manufactured by Rust-Oleum.
It is highly suggested that the labels and Technical Data Sheets (TDS) (see link for .pdf) be reviewed prior to use of this product and any product for that matter. When reviewing the TDS it becomes clear that this material is not intended for professional remediation.
Firstly, the TDS reads, “Mold Killing Primer is for use on non-porous interior and exterior.” Any material that requires encapsulation by a remediation company will typically be highly porous, mainly plywood and lumber. Generally material that is non-porous is typically non-conducive, such as metal, concrete and plastic. The actual purpose of this material is sometimes questioned.
Second, the label reads “Do not apply when air or surface temperature is below 50°F,” this would typically eliminate all winter attic remediations.
Third, the label implies that this is a first coat product and requires a top coat to complete the system and cover any stains. That is because the material is as the label states, a primer.
Because some written information in the TDS can be ambiguous, the manufactures’s technical department was contacted regarding the following questions:
1) Although the TDS lists attics as acceptable locations for use, please clarify the use of this product as wooden assemblies where this product would be used are porous. RESPONSE: This product can be used in a variety of buildings and their location, however, the material is not approved for use on porous materials in these locations, including wood.
2) Will Zinsser block staining or bleed-through of mold stains? RESPONSE: It is not recommended that Zinsser be used without a stain blocking application, such as BIN product.
3) Is Rust-Oleum considered an encapsulant alternative for use in mold remediation? RESPONSE: This material is not an encapsulant. It is intended as a primer. Its use as an encapsulant is not guaranteed or warranted.
The bottom line is, Zinsser is not intended for use by professionals. Encapsulate materials are intended to be absorbed into the material being treated. This application will kill anything that is rooted and seal the surface preventing further growth or new growth. Zinsser is a surface application. Zinsser will seal a surface and prepare it for a finish coat, but it will not be absorbed by the substrate being treated. Some Zinsser applications are known to fail and delaminte under high moisture and relative humidity conditions. Rust-Oleum does not guarantee the use of Zinsser in an attic.
If you hire a professional remediation service, expect professional remediator work practices and materials.
This product is great for small homeowner jobs <10SF.
Bald Eagle Inspection Services, LLC is a leading Mold Assessment company providing services in the Upstate New York areas and beyond.