enhancing propolis envelope

I described the honey bee health benefits of a propolis envelope in an earlier post. 

• lowered immune response expression
• less bacterial growth in brood food
• lower number of chalk brood mummies
• reduced severity of American Foulbrood

In March of this year, I added a box where I created side-by-side patches of shallow grooves with a dremel tool and router bit. After honey harvesting, I removed this box and analyzed the interior wall for propolis.  I cropped the photo so exactly 11 grooves in each patch are included in the comparison of: 

• 1/4 inch (6.4 mm) wide shallow grooves (on the left)
• no grooves (seen between two patches)
  
• 1/8 inch (3.2 mm) wide shallow grooves (on the right)

In the first photo, propolis appears as a red film which is distributed everywhere, but groove edges have a thicker red film. In the second photo, I used SimpleCV to mask out areas of thin propolis film.   In the third photo, I used SimpleCV to draw regions of thick propolis and compared 3 regions:

• 61.5% of thick propolis area was associated with 1/4 inch (6.4 mm) wide shallow grooves (on the left)
• 0.5% of thick propolis area was associated with no grooves (seen between two patches) - look at the bottom of the photos for thick propolis in the no groove region
  
• 38.0% of thick propolis area was associated with 1/8 inch (3.2 mm) wide shallow grooves (on the right)

I'm not suggesting 1/4 inch wide shallow grooves is the best option.  More narrow 1/8 inch grooves pack into the same length of box wall than wider 1/4 inch grooves.   There's no significant propolis advantage of either groove width except to say grooves outperform doing nothing with regards to enhancing a propolis envelope.