#1063 1954 Lewis/Clark W/ And W/O Gum Breakers

I noticed that there seem to be two versions of this stamp. I have...

Plate #25022 without any sign of gum breakers ridges.

Plate #25024 with obvious gum breaker ridges.

(I don't have examples of the other two plate numbers : 25021 and 25023.)

The gum also looks a little bit different (25022 whiter and perhaps a different formula). However, this gum appearance could be within the range of environmental/storage variation over the years.

The stamp printing looks very slightly different, with 25022 looking crisper. Again, perhaps within normal range of production variance.

There is no mention of a difference in the Scott Specialized. Durland (2000) just says "Dry Printed" for the whole issue, but says nothing else about any different types.

I do not think it is coincidence, however, that Durland's #1063 listing is the last before the listings for the 1954 (Liberty) series and Durland makes the comment there "... the BEP did considerable experimenting during this period."

Questions:

- Is the gum breaker difference consistent for these two plate numbers, or does one or the the other, or both, come in both types?

- If not consistent, is there any scarcity difference for one or the other?

- Is this discussed in the literature anywhere?

I have all sixteen plate block positions of #1063. All have gum breaker ridges and I see no significant difference in gum color or crispness of the face, particularly for stamps that are sixty-one years old.

In order to look at this further, we would need pictures/scans of the stamps, especially of the gummed backs.