Cytiva's Whatman Grade 542 filters are acid hardened to allow high retention of fine precipitates in applications such as metal determinations and hydroxide collection. High wet-strength Acid-hardened for resistance to strong acid and alkali solutions Nominal particle retention rating of 2.7 µm Herzberg filtration speed of 2510 s Extremely low ash content (0.006% ash maximum) Along with Grade 542 cellulose filter paper, the Whatman range of hardened quantitative papers from Cytiva's business includes fast Grade 541 and general-purpose Grade 540 filters. All three grades are designed for use in quantitative analysis with strong acid/alkali solutions. Slow flow rate filters for gravimetric determination Hardened Grade 542 quantitative papers enable high retention of fine particles in chemically harsh conditions. When acting as a gravimetric filter, this cellulose filter paper is therefore well suited for use in capturing fine precipitates in applications such as metal determinations and hydroxide collection.