WordNet
sealing material
n. any substance used to seal joints or fill cracks in a porous surface
Usage examples of "sealing material".
Given the obscuring effect of the sealing material, it was hard to be sure, but somehow he could not really doubt the fact.
With swing curtailed by his position, he aimed the point of the sword into the lower end of the slit, picking time and time again at the same portion of sealing material.
The Terran could see none of the black sealing material, unless it was used as mortar to set those bricks.