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The Conversion Gel[2] is a testing element used in the Enrichment Center several decades before Portal, and appears in Portal 2. It is one of three types of Mobility Gels.


Conversion Gel is a white fluid that allows the Portal gun to place portals on surfaces that would normally be unfit for placing portals. Several areas in the Condemned Testing Facility seem to indicate that the Conversion Gel was used to paint all further testing facilities, explaining how only white-painted walls were affected by the Portal Gun.

According to a pre-recorded message from Cave Johnson, the Conversion Gel is made up of ground-up Moon rocks, as they are an excellent portal-conducting surface, although contributing to Cave's death due to being poisonous.

This becomes important at the end of the game, where the only bit of Conversion Gel left in the core room was a small spot underneath Wheatley, but a hole opens in the ceiling revealing the Moon. Chell fires one portal at the moon, and another on the Conversion Gel puddle beneath Wheatley, causing a rapid decompression in the room under Wheatley, blowing him and the Space Core out into the vast void.

Behind the scenes[]

  • Out of the three gels featured in Tag, only the purple one, allowing the player to walk on walls and ceilings, has not been converted for Portal 2. When asked during GamesCom '10 about the possible inclusion of a third gel and its nature being that of Tag's purple gel, Erik Wolpaw only answered that there would indeed be a third gel, but did not expand on its nature.[3] Erik has recently revealed that the third gel that allowed the player to walk on walls and ceiling was developed into the game, but was cut because it did not add complexity to the puzzles and created a nauseating feeling for players.[4]

List of appearances[]


  • Despite apparently being poisonous, like with the Repulsion Gel, getting covered in Conversion Gel does not seem to adversely affect the player in any way.