Mucus can be of different thickness and viscosity. Here is an example of paper which talks about the mucus gel http://ajpgi.physiology.org/cgi/content/full/280/5/G922 "the mucus layer consists of two components, a loosely adherent gel that can be removed by suction and an underlying firmly adherent gel that remains. The relative thickness of the two component layers of the mucus gel varies for different regions of the gut. Thus in the stomach, the thickness of the firmly adherent mucus component is 80 and 154 ï¿½m for the corpus and antrum, respectively, with an overlying layer, of similar thickness, of loosely adherent mucus that can be removed by suction. In contrast, in the small intestine, practically all of the mucus gel could be removed by suction to leave a very thin discontinuous mucus gel layer, with several tops of the villi apparently free of mucus. In these studies, the mucus between villi was also removed during the suction procedure, which otherwise would offer an ~500-ï¿½m-thick layer covering the crypts and the basal villus epithelium. In the colon (mean mucus thickness, 830 ï¿½m), and to a lesser extent the ileum, the mucus layer was very thick (up to 4-fold thicker) compared with that in other regions of the gut. Most of the difference in mucus thickness was due to the loosely adherent mucus"