Chinese provisional postage dues are hard to find on cover               The provisional issue of 1904 (Scott J1-6) was the first Chinese postage due series.             Prior to this issue, letters with insufficient franking were marked as such and forwarded for delivery with the addressee called upon to pay the postage due.             Postage due stamps became a requirement when China joined the Universal Postal Union.   The Chinese postal administration ordered postage due stamps to be printed by Waterlow  & Sons of London, England. In the interim before the postage due stamps arrived, postal officials overprinted six values of the 1902-07 series of Coiling Dragon stamps on unwatermarked paper.             The stamps were overprinted “Postage Due” in English above the Chinese two-character equivalent.             The stamps range in denomination from ½¢ to 10¢.             Figure 1.   The 4¢ red-brown stamps (Scott J4) is shown in Figure 1.             The overprinted stamps were printed in sheets of 12 20-stamp panes separated by horizontal and vertical gutters with wide selvage all around.             Because the overprinted postage due stamps are worth more than the postage stamps that have not been overprinted, counterfeit overprints are known on genuine stamps. Most are crudely executed.             The Scott Standard Postage Stamp Catalogue values an unused, hinge set of six provisional postage due stamps at $89 and a used set at $43.50.             A few errors are known to exist. The 5¢ is known imperforate at top and with the left gutter margin imperforate. Both of these errors are quite scarce. A used 10¢ vertical pair imperforate between is known (Scott J6a) and is worth every bit of its Scott standard catalog value of $475 or more.             Many collectible varieties exist, including perforations, shades, plate scratches and gutter pairs.             This issue is very difficult to find on cover.             Figure 2   A cover mailed Feb. 16, 1906, from Stolden, Switzerland, to the American Baptist Mission in Jia-ding County, Szechwan province, is shown in Figure 2.             The Swiss 5-centime stamp franking the cover was insufficient to pay the postage so a desirable gutter pair of 1¢ ocher provisional postage due stamps (Scott J2) was applied.             The postage due stamps are tied by a reversed image grid cancel and an indistinct Bao-Ji, Szechwan postmark dated March 25, 1906.                 Originally published in Linn’s September 1, 2008