The thin layer of new wax that bees build over the top of cured (or dried) honey is called capping wax. Although bees cap brood cells one at a time, they cap honey cells in groups. Once an area of comb is ready to cap, the bees may cover many square inches at once. This different way of capping partially accounts for the flatter surface of honeycomb as compared to brood comb.
Depending on their genetics, bees either place the capping wax directly on the surface of the honey, or they may leave a little air pocket between the surface of the honey and the wax. These two methods make no difference in the flavor, color, or quality of the honey, but they make the finished combs look dramatically different.
The honeycomb with the air pockets is said to have dry cappings. The comb appears white or very light tan. Honeycomb with wet cappings is not actually wet, but it looks like it might be. The appearance is darker and may have a variegated pattern due to scattered mini air pockets, which have a lighter color.
While some honey bees produce both types of capping, some consistently build one kind or the other. Italian honey bees (Apis mellifera ligustica) are known for producing white, dry caps. At the other end of the spectrum, Caucasian bees (Apis caucasica) produced wet caps almost exclusively.
Producers of comb honey have found that consumers prefer dry cappings. Especially back in the heyday of comb honey production, beekeepers found they could get better prices for light-colored, clean looking combs. The desire for white combs is one of the reasons that Italian bees became so popular in the United States.
The practice of producing chunk honey, which is just a piece of honeycomb submerged in extracted honey, was one way in which beekeepers could sell their wet-capped honey.