The test method details a standard procedure for determining the porosity of white or near-white mineral oil insoluble paint films by staining to indicate the degree of penetration of subsequent coatings. This test method shall require the use of a film applicator, reflectometer, vacuum extraction plate, camel hair brush, plastic washing bottle, test plate, penetration medium and filter paper. The test paint was applied to a non-porous surface, air dried, and then the reflectivity was measured. A special colored penetrating medium was applied to remove the excess in the specified manner and the reflectivity was measured again. The difference between two readings indicates porosity; The smaller the difference is, the lower the porosity of the film is and the stronger the resistance to penetration is.

ASTM D3258-2019 Porosity of Paint Film Abstract

Ambito di applicazione
1.1 The test method covers the determination of the porosity of white or near-white mineral oil insoluble paint films to indicate the degree of penetration of subsequent coatings.

1.2 The texture of the film will affect the cleaning and thus the test results. A stain applied to a high shading paint does not reduce the reflectivity as much as the same stain applied to a low shading paint with equal porosity. These points need to be considered when comparing different paints.

1.3 I valori espressi in unità SI sono considerati standard. I valori indicati tra parentesi sono solo di riferimento.

ASTM D3258-2019 Porosity of Paint Film Abstract

1.4 Questo standard non è destinato ad affrontare tutti i problemi di sicurezza, se presente, legati al suo utilizzo. È responsabilità dell'utente di questo standard stabilire la sicurezza adeguata, pratiche sanitarie e ambientali e per determinare l'applicabilità delle restrizioni normative prima dell'uso.

1.5 La presente norma internazionale è stata sviluppata in conformità con i principi di standardizzazione riconosciuti a livello internazionale stabiliti nella Decisione sui principi per lo sviluppo di norme internazionali, Linee guida e raccomandazioni emesse dal Comitato sugli ostacoli tecnici al commercio dell'Organizzazione mondiale del commercio.