An attempt to unambiguously distinguish Scott's #178's from Scott's #183's
Howard M. Relles
rellesh@yahoo.com

An attempt to unambiguously distinguish Bank Note Stamps #178, printed on "yellowish wove paper", from #183, printed on "soft porous paper", is described below.  It is based on the expected phenomenon that soft porous paper will wick water faster than harder wove paper.  (The data for a group of Official Stamps, whose identification was also augmented using the paper's wicking behavior, can be found at:  http://www.rellesart.com/Wicking102104.html  .)  (See also:  http://www.rellesart.com/Wicking92804.html  ).

2004 Scott's descriptions:
#178: printed by Continental Bank Note Co., "yellowish wove paper", 1875, Perf. 12, image A45a, 2¢ vermillion, Mint: $425.00, Mint NG: $180.00, Used: $10.00.
#183: printed by American Bank Note Co., "soft porous paper", 1879, Perf. 12, image A45a, 2¢ vermillion (also: orange vermillion), Mint: $140.00, Mint NG: $55.00, Used: $3.00.

I began with 10 stamps that are either #178's and/or #183's which presumably should differ only by the type of paper they were printed on (according to the above Scott's descriptions).  All are Used, have no grills, and are some version of vermillion (or orange vermillion) color.  I couldn't tell them apart by the paper "look and feel" criteria.  However, since I would expect soft porous paper to wick water faster than a harder wove paper, I decided to try some wicking experiments.

First, I completely removed all remnant of hinges or residual gum (from hinges) in warm (about 140F) water.  After drying, I still could not tell which (if any) were printed on "yellowish wove paper" and which (if any) were on "soft porous paper".

Initially, I marked a line in pencil that was 15.0mm from the bottom of each stamp and planned to hold each so that the bottom perfs were just touching a layer of water.  (The plan was to measure the time it took for the water to wick to the the line.)  Adjusting and maintaining the exact same depth of immersion for each stamp proved quite difficult.  Also, the vertical wicking looked like it was going so slowly that I began to worry about the competing process of evaporation of the water as it moved up the stamp.  So, I tried a different approach.

I put a 3.5-4.0mm (error source #1) drop of water on the back of each stamp on a horizontal surface, allowed it to form its mostly (error source #2) circular wicking pattern for 60 seconds, and then marked the edges of the circle with a pencil, taking care to not disturb the softened wet area.  The remaining (unabsorbed) water was blotted off and the stamp was allowed to dry in air (at 60% rel. humidity).  When dry, the wicking limit marks were connected with pencil to make sure they were not confused with other marks.  Then the distances between the marks was measured.

Results:
Considering the errors that are possible in the above method and the 125+ year history of each stamp, this technique might be of some help in identifying which stamp is made with "soft porous paper" (#183) and which is not (#178).  Roughly speaking, those stamps that wick in the 9-12 mm range would probably be #183 while those in the 5-6 mm range would probably be #178.
Unknown Stamp
Trial Number
 Max. Wicking Distance (mm)
(average of 3 or 4 tests)
 Probable ID of Stamp
(Scott's #)
#A-91604
 10.2 ± 0.6
 183
#B-91604
 12.3 ± 0.9
 183
#C-91604
 8.9 ± 0.6
 183
#D-91604
 9.8 ± 1.0
 183
#E-91604
 4.5 ± 0.5
 178
#F-91604
 8.9 ± 0.4
 183
#G-91604
 6.3 ± 1.0
 178
#H-91604
 4.9 ± 0.2
 178
#I-91604
 10.3 ± 0.5
 183
#J-91604
 10.0 ± 1.2
 183

Additional testing of known and unknown #178's and #183's is planned.


Experimental:

 
#A-91604:  maximum wicking distances: 4.0, 10.0, 9.5, and 11.0 mm; the 4.0 mm distance was obtained on a distinctly thin area of this stamp where less paper would mean less wicking.  The first three values: Average: 10.2 ± 0.6 mm.

 
#B-91604: maximum wicking distances: 11.0, 14.0, 12.0, and 12.0 mm.  Average: 12.3 ± 0.9 mm.

 
#C-91604: maximum wicking distances: 8.0, 10.0, 8.5, and 9.0 mm.  Average: 8.9 ± 0.6 mm.

 
#D-91604: maximum wicking distances: 11.5, 9.5, 10.0, and 8.0 mm.  Average: 9.8 ± 1.0 mm.

 
#E-91604: maximum wicking distances: 5.0, 4.5, 5.0, and 3.5 mm.  Average: 4.5 ± 0.5 mm.

 
#F-91604: maximum wicking distances: 8.5, 8.5, 9.0, and 9.5 mm.  Average: 8.9 ± 0.4 mm.

 
#G-91604: maximum wicking distances: 6.5, 8.0, 6.0, and 4.5 mm.  Average: 6.3 ± 1.0 mm.

 
#H-91604: maximum wicking distances: 5.0, 5.0, 4.5, and 5.0 mm.  Average: 4.9 ± 0.2 mm.

 
#I-91604: maximum wicking distances: 11.0, 10.0, 10.5, and 9.5 mm.  Average: 10.3 ± 0.5 mm.

 
#J-91604: maximum wicking distances: 11.5, 9.0, 11.0, and 8.5 mm.  Average: 10.0 ± 1.2 mm.