Grout retention or grout staining is a specific concern to end users. An installation that experiences grout staining is often expensive to fix. Currently ASTM does not have an adequate test method to evaluate this issue. We have found that the ASTM Stain Resistance Test (C1378) does not always identify surfaces that will be susceptible to grout staining.
Causes of unacceptable grout retention can include (but are not limited to): tile manufacturing issues, grout manufacturing issues, and/or installation issues.
It is acceptable for specific products to retain a small amount of grout. Therefore not all
grout retention is detrimental. It is necessary to evaluate each system on a case by case basis.
Some types of tiles require the use of a grout release (or sealer) per manufacturer's instructions. Installation instructions shall be taken into account when evaluating various systems.
Grout retention characteristics are a function of the materials being used and installation practices. The industry needs a method to differentiate this criteria and troubleshoot issues.
This method is intended for:
•? Use by installers to determine if the tile and installation materials are synergetic
•? Use by tile and gout manufacturers to evaluate production
•? As a tool for forensic flooring specialists to determine if the tile/grout system was
The title and scope are in draft form and are under development within this ASTM Committee.