Knife dulls overnight after sharpening

[Jan]

So, the Victorinox spend another 24 hours relaxing in the drawer.  I pulled it out and tested from handle to tip:
135, 140,130, 105

After one pass each side of blade with the leather belt on the Kally:
120, 100, 100, 105

In summary over two days:

First sharpening: 110, 130, 110, 125
After overnight : 160, 150, 150, 175
After stropping : 125, 110, 105, 100
Overnight #2   : 135, 140, 130, 105
After stropping : 120, 100, 100, 105

Mr. Grepper thanks again for posting very interesting sharpness data.

When I was thinking about your recent results the following interpretation occurred to me.
Average sharpness drop over the first night after sharpening was 40 gf, while the sharpness drop of the stropped edge over the second night was less than 20 gf. I consider it as a statistically significant difference.

My hypothesis interprets the sharpness drop over the first night as an edge misalignment caused by the relaxation of major part of residual stresses in the edge after sharpening. Stropping after the first night probably does not generate additional residual stress in the edge and so the smaller sharpness drop over the second night can be interpreted as relaxation of the minor part of the remained residual stresses generated by the initial sharpening.  

Jan

P.S.: A short general consideration (not fully relevant to overnight knife dulling)

Residual stresses which resides inside the sharpened blade after removing all applied forces may be compressive (pushing the steel together) or tensile (pulling the steel apart).
   
Residual stresses acting over long distances are called macro-stresses while residual stresses existing inside a steel grains (or between grains) are called micro-stresses. In my understanding the overnight dulling may be caused by relaxed micro-stresses.

When a knife blade is bent, tensile and compressive stresses are generated in the blade.

When the bent blade does not spring back, we know that some atomic bonds were broken. However not all bonds were broken, and in some regions we still have not broken bonds which remain stressed. Those bonds are stacked because they are not stressed enough to brake and also not strong enough to spring the blade back. Generally more atomic bonds are broken in the tensioned regions than in the compressed ones.

The fighting between regions in compression and tension is what I understand under the term residual stress.