Glue Soak is the second upgrade for the Glue Gunner in Bloons TD 4 and the first upgrade on the 1st path on Bloons TD 5. It costs $170 on Easy, $200 on Medium, $215 on Hard and $240 on Impoppable. When a Bloon is glued by this upgrade, the glue soaks through the bloon layers gluing all of its decendants. This does not affect M.O.A.B. Class Bloons as Glue Gunners don't attack them. Without this upgrade, popping a glued bloon would make the glue eventually. Gluing a Ceramic Bloon would be pointless without this upgrade, because Ceramic Bloons cannot be slowed down by glue, except in the Mobile/Steam versions.