WHY
Because you want fit her the added filtering speed [•refolding «rives, or you want the convenience of not having to fold the paper yourself. Take a close look at the illustration. It is obvious at a glance t h a t the usable filtering area ha« been increased by 50% over the routine method of folding. Ever, though you don't fret a full 50% increase in filtering· speed, medium grade» like Nos. 1 and 2, and very rapid grades like No. 4, do show a marked increase. (Unfortunately prefoldingr doesn't do a thing for the very slow retentive grades t h a t really need it ). No one has yet developed a completely logical and foolproof method for numbering filter, paper grades. When Whatman No. 2 is ρ refolded i t i« called No. 12, but the pre folded version of Whatman No. 1 is Xo. J 3 ("The number 11 has been usurped years before by a special paper for tannin analysis;. On the oilier hand Whatman No. 4 when prefolded is called, logically enough, No. 4 FOLDED. So wifch'Xo. 02 which becomes No. 52 FOLDED. If you would like a copy of our new catalog which unlocks all those numbering mysteries drop us a line. We will include samples of the prei'oided grades as well.
USE
A
PREFOLDED FILTER
PAPER?
Whatman FILTER
PAPER
Sole sales agents: reeve angel 9 Bridewell. Place, Clifton, N. J. 9 Bridewell Place, London, EC4
