Quantitative
Filter Papers are made from the highest quality alpha cotton cellulose.
One critical step in the manu-facture of these filter papers is acid washing.
Papers are either single acid washed in hydrochloric acid or double acid
washed in hydrochloric then hydroflouric acid to further reduce levels of
Si02 CaO and Fe2O3. Following the acid wash, all papers are rinsed with
ultrapure water to neutra-lize them. No. 3
Single acid washed in HCI, this medium retention (5-10 µm) fast flow
rate paper is recommended for general purpose filtering. This paper has
good chemical resistance and wet strength. No.5A
This is a double acid washed paper of low ash to retain coarse precipitates
(>10 µm) with high flow rates. Recom-mended for filtering hydroxides,
metallic aerosols and de-termining silica content in steel. No.5B This is a double acid washed paper for retaining medium size (5-10
µm) precipitates. General purpose paper. No. 5C A double washed paper with slow flow rate and high
retention efficiency
Recommended for collecting particles (<5 µm), gravimetric analyses
and for collecting precipitates that tend towards colloidal dispersion.
No. 6 High purity, low ash paper for retaining medium fine (2-10 µm)
particulates. Uses are primarily precision analyses of trace and precious
metals, beverages, water, etc. No. 7 This is the highest purity quantitative paper available with fast
flow rate for retaining medium size particles (5-10 µm). Recommended
for gravimetric analyses of minute trace and precious metals and for research
labs where precision is a high priority.
N0.4A This acid washed paper is further treated with nitric acid to harden
the paper for superior wet strength. No 4A paper has a high retention efficiency
for fine particulates (<5 µm), excellent pH and chemical resistance.
