Distinguishing 3¢ and 10¢ Bank Note Issues printed on "white wove paper" from those printed on "soft porous paper".
Howard M. Relles
rellesh@yahoo.com

An attempt to unambiguously distinguish Bank Note Issues printed on "white wove paper" from those printed on "soft porous paper" is described below.  It is based on the expected phenomenon that soft porous paper will wick water faster than hard paper.  (This is a second group of stamps whose identification is being augmented using the paper's wicking behavior; see the effort to distinguish Bank Note Issues #178 and #183 from one another:  http://www.rellesart.com/Wicking91604.html .)  (See also: http://www.rellesart.com/Wicking102104.html  .)

Fifteen Bank Note Issues (eight 3¢ Washington's & seven 10¢ Jefferson's) were completely freed of all remnants of hinges or residual gum (from hinges)(there were no "mint" examples in this study) in warm (about 140F) water.  After drying and allowing them to remain at 80°F (60% relative humidity) for at least 24 hours, I still could not tell by feel which (if any) were printed on "white wove paper" and which (if any) were on "soft porous paper".  They all felt too similar to allow for a definitive identification.

I then put a 3.5-4.5mm drop of water on the back of each stamp on a horizontal surface, allowed it to form its mostly circular wicking pattern for 1 minute, and then marked the edges of the circle with a pencil, taking care not to 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.  The results are listed in Table 1.

I next decided to measure the wicking distance vs. time over a longer period and to take a measurement every minute.  Again, I carefully placed a 3.5-4.5mm drop of water on the back of each stamp on a horizontal surface and allowed it to form its mostly circular wicking pattern.  The maximum wicking distance (the largest diameter of the mostly circular wicking pattern) was measured every minute for 5 minutes taking care not to disturb the remaining drop or the wet area.  These results are listed in Table 2.

Results & Discussion:
The data in Table 1. are instructive.  But, from these data, it looks like just measuring the wicking distance at 1 minute gives results that probably cannot discern intermediate wicking behavior (see Test Stamps B-92804 and M-92804 in both tables).

The data in Table 2. are more useful.  Of the 15 test stamps, 13 fit into two distinct wicking categories: (a) very little wicking (distance/time: 0.3 mm/min.) and (b) considerable wicking (distance/time: 2.1 or greater mm/min.).  I've assigned the little or no wicking examples to varieties printed on "white wove paper" (1870-1873, National Bank Note Co. & Continental Bank Note Co.) and the considerable wicking examples to those printed on "soft porous paper" (1875-1882, American Bank Note Co.).

The other two stamps, B-92804 and M-92804, showed intermediate wicking behavior.  Scott's 2004 U. S. Speicalized Catalog indicates that the "white wove paper" used for #145-155 is "thin to medium thick" and that used for #156-166 is "thin to thick".  Such thickness variation in either the "white wove paper" or the "soft porous paper" could explain why all of the stamps do not fall into just two distinct and narrow wicking categories.  Further studies are needed to see just how broad this method could be for discerning paper types.  Naturally, one would not want to use it for stamps with gum since removal of the gum (to do wicking on nearly pure paper) could seriously decrease the stamp's value.  And just how grills (light, medium, and heavy) would affect wicking is yet to be determined.

Table 1.  Wicking Distances (mm) for BANK NOTE ISSUES at 1 minute.

Test Stamp
 BANK NOTE: Partial Description (all used)
 Wicking Distances (mm) at 1 minute
A-92804
 3¢ Washington, green, no grill, no secret mark
 3.5, 4.5, 5.0, 5.5
B-92804
 3¢ Washington, green, no grill, no secret mark 4.0, 4.5, 4.5, 5.0
C-92804
 3¢ Washington, green, no grill, secret mark 3.5, 4.0, 4.0, 5.0
D-92804
 3¢ Washington, green, no grill, secret mark 5.0, 6.0, 6.0, 6.5
E-92804
 3¢ Washington, green, no grill, secret mark 10.5, 12.5, 13.0, 15.0
F-92804
 3¢ Washington, green, re-engraved
 9.0, 9.5, 10.0, 12.0
G-92804
 3¢ Washington, green, re-engraved 7.0, 7.0, 7.5, 7.5
H-92804
 3¢ Washington, green, re-engraved 4.0, 5.5, 6.0, 6.5, 8.0
I-92804
 10¢ Jefferson, brown, re-engraved
 10.0, 10.0, 10.5, 11.0, 19.0*, 20.0*
J-92804
 10¢ Jefferson, brown, re-engraved 8.5, 9.5, 9.5, 9.5
K-92804
 10¢ Jefferson, brown, re-engraved 11.0, 11.0, 13.0, 13.0
L-92804
 10¢ Jefferson, brown, re-engraved 7.5, 9.0, 9.0, 11.0, 11.5
M-92804
 10¢ Jefferson, brown, re-engraved 5.5, 6.0, 6.0, 6.5
N-92804
 10¢ Jefferson, brown, re-engraved 7.0, 7.5, 9.0, 10.0
O-92804
 10¢ Jefferson, black-brown, re-engraved 9.5, 11.5, 12.0, 14.0, 14.5
*The 19.0 and 20.0mm wicking distances occurred across a delayered area of the back of the stamp.


Table 2.  Wicking Distances (mm) for BANK NOTE ISSUES vs. Time (min.)

Test
Stamp
-92804
 Partial
Description
(also see Table 1.)
 0
min.
 1
min.
 2
min.
 3
min.
 4
min.
 5
min.
 Slope
mm/min.
 Paper
Type
 Stamp I. D.
(Scott's #)
A
 3¢ Washington
 4.0
 4.5
 5.0
 5.0
 5.5
 5.5
 0.3
 white wove
 147
B
 3¢ Washington
(2 tests)
 4.0
4.0
 5.0
5.0
 7.0
6.5
 8.0
7.0
 9.0
8.0
 9.5
9.0
 1.1
1.0
 (a)
 147
C
 3¢ Washington 4.0
 4.0
 5.0
 5.5
 5.5
 5.5
 0.3
 white wove
 158
D
 3¢ Washington 4.0
 5.0
 5.0
 5.0
 5.5
 5.5
 0.3
 white wove
 158
E
 3¢ Washington 4.5
 14.0
 19.5
 22.0*
 -
 -
 >3.5
 soft porous
 184
F
 3¢ Washington 4.0
 9.0
 12.0
 14.0
 15.0
 15.5
 2.3
 soft porous
 207
G
 3¢ Washington 4.0
 8.0
 10.5
 12.0
 14.5
 15.5
 2.3
 soft porous 207
H
 3¢ Washington 3.5
 6.0
 9.0
 13.0
 16.5
 18.0
 2.9
 soft porous 207
I
 10¢ Jefferson
 4.5
 11.0
 14.0
 15.5
 17.5
 18.5
 2.8
 soft porous 209
J
 10¢ Jefferson 4.0
 9.0
 12.0
 13.5
 14.5
 15.5
 2.3
 soft porous 209
K
 10¢ Jefferson 4.0
 13.5
 16.5
 19.5
 23.0*
 -
 >3.8
 soft porous 209
L
 10¢ Jefferson 4.0
 9.5
 12.5
 14.0
 15.5
 17.0
 2.6
 soft porous 209
M
 10¢ Jefferson
(3 tests)
 4.5
4.0
4.0
 9.0
5.0
5.5
 10.0
5.5
6.5
 11.0
6.0
7.5
 11.0
6.0
8.0
 11.0
6.5
8.5
 1.3
0.5
0.9
 (b)
 209
N
 10¢ Jefferson 3.5
 8.5
 11.0
 12.0
 13.0
 14.0
 2.1
 soft porous 209
O
 10¢ Jefferson, black-brown 4.0
 12.0
 15.5
 17.0
 18.5
 20.0*
 >3.2
 soft porous
 209b
* Water had wicked to the edge of the stamp between the last two measurements.  Thus, the final measured value is only a minimum.
(a) Intermediate wicking behavior.  Possible thickness variation from the norm.
(b) Intermediate and even variable behavior on a single stamp (thickness variation across a single stamp?).