Adhesion Gel can be used in game by creating a gel dropper with a paint ID of Stick. It will have the appearance of an unpainted object. This also means any object coated in Adhesion Gel will not appear to be. As the gel was not finished at the time of Portal 2's release, its blob texture is missing, thus giving it the purple/black checkerboard appearance, unless its already painted a surface. This gel, however, does not allow players to walk on walls and ceilings. Any object coated in Adhesion Gel will also not slide around in a puddle of propulsion gel. It is a purple gel that causes any object covered in Propulsion Gel to ignore its speed enhancing abilities, effectively canceling it out and causing the object to come to an immediate stop.
Even though it does not appear in the game in canon, it still exists within the game files.The sign to be used in Test Chambers for this gel was created and can still be found in the game files.However, playtesters tended to get nauseous after using it as its effect was very disorientating, hence its removal from the game. Based on the blue paint appearing in the video game Tag: The Power of Paint, it was to allow players to walk on walls or ceilings covered with the gel.Adhesion Gel in the Perpetual Testing Initiative.
