A.David Dobson, an architect and licensed general and glazing contractor in San Diego, responds: On most job sites (and even in the promotional material of many manufacturers), I've found that applicators usually drag caulked sealants when they apply them. But it's hard not to pull the caulking gun too quickly and stretch the caulking bead, which will prevent enough sealant from being applied to the joint.
Applied too thinly, a caulked sealant can suffer from cohesive failure, meaning it's not strong enough to maintain its bond. Or, it can shear (split) along the length of the joint. This is particularly a problem when a sealant is used to create a "bridge" joint, where the gap between two materials is simply painted over — rather than filled —...
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