Naphthenic oils reduce microbial growth in silicone

A recent study shows that a transparent RTV-1 acetoxy curing silicone sealant extended with 20 wt% naphthenic specialty products has a lower level of microbial growth compared to other extending alternatives in the market.

Within the European Union, sealant material for the construction industry requires a CE marking to be placed legally on the market. Silicone sealants are common materials in the construction industry. They are appreciated for their thermal and chemical stability.

To achieve a CE marking the sealant needs to meet the standards of EN ISO 15651-(1-5):2017, depending on area of application. For sealant materials applied in sanitary joints, the material is tested according to part three, which includes testing of microbial growth according to EN ISO 846. The growth intensity is evaluated visually according to a rating scheme from 0 to 5.

Microbial growth on sealants can cause permanent staining and/or etching and shorten the lifespan of the joint.

A recent study shows that a transparent RTV-1 acetoxy curing silicone sealant extended with 20 wt% naphthenic specialty products has a lower level of microbial growth compared to other extending alternatives in the market.

Pictures show sample replicates directly after exposure, before cleaning procedure. Samples extended with NYFLEX® 2120B and PAR 4 cSt respectively.


Figure 1. Acetoxy curing silicone sealant extended with NYFLEX® 2120B.


Figure 2. Acetoxy curing silicone sealant extended with PAR 4 cSt.

Emma Öberg is a Development Engineer, Chemical Manufacturing Industry, Nynas Naphthenics. She joined Nynas in 2016.