ISO 11402:2004 specifies three methods for determining the free-formaldehyde content in the following:
- Phenolic resins, by potentiometric titration in aqueous or organic solution (hydroxylamine hydrochloride procedure). The method is applicable to resins with free-formaldehyde contents up to and including 15 % by mass. For free-formaldehyde contents between 15 % by mass and 30 % by mass, it may be necessary to adjust the concentrations of the standard volumetric solutions used accordingly.
- Amino resins and furan resins (sulfite procedure). The method is applicable to resins resulting from the polycondensation of urea and melamine with formaldehyde and to furan resins resulting from the polycondensation of furfuryl alcohol with formaldehyde without further modification.
- Condensation resins (KCN procedure), including urea resins, furan resins, melamine resins and phenolic resins, as well as combinations and modifications of these resins.
The purpose of this International Standard is to establish recognized and useful determination procedures (for instance in order to check whether official regulations on the handling of hazardous workplace materials are observed).
The free-formaldehyde content determined in formaldehyde condensation resins using this International Standard represents the actual content at the time of the determination. The value bears no quantitative relationship to the free-formaldehyde content during or after processing.