Portal 2 Puzzle Maker: Gel

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This article contains content specific to the Portal 2 Puzzle Maker. For the Authoring Tools equivalent, see Gel (Portal 2).
The Repulsion gel effect.

Gels are testing elements in Portal 2. They are dispensed from droppers and cover any non-glass surface or object they splash on, changing its physical properties. Cleansing (water) streams behave the same way gel does, but clean gel off of surfaces and objects. Gel streams can be redirected with portals and Tractor Beams, and can pass through Grating.

The different gel types are individual test elements to choose from the Puzzle Maker menu. However, an already-placed gel splat can be changed for a different one by changing its properties (see below).

There are four types of gel:

  • Repulsion gel is blue, and causes the player and physics objects to bounce off of the painted surface. Objects painted with Repulsion gel will bounce around randomly off of any surface, even if set down gently. This allows it to be used as a weapon against turrets, which will bounce around comically when painted until destroyed by a Fizzler or Goo pit. The player can avoid bouncing off a surface by crouching.
  • Propulsion gel is orange, and makes objects and surfaces slippery. Players will accelerate more than twice as fast as the normal speed when running across a surface coated in propulsion gel, objects will slide across the surface for some distance, and objects painted with the gel will slide across any smooth surface. The player can avoid unwanted acceleration by moving carefully or crouching.
  • Conversion gel is white, and allows the placement of portals on otherwise non-portalable surfaces. It can be a very dangerous tool to give to a player, as it can allow them to easily break most puzzles unless you carefully account for the assumption that they will be able to portal to any non-glass surface.
  • Cleansing "gel" is simply water which washes paint off of any surface or object. It can be a good idea to provide this to a player if you give them repulsion gel, as otherwise they might unintentionally render a puzzle unsolvable by painting a cube which is not replaced. It can also be used to restrict the use of gel on a surface or object below the dropper. Placing Cleansing blobs without a dropper has no apparent useful effect.

Item Properties

Entity Costs:

  • Droppers: 15 (all types)
  • Conversion blob: 9
  • All other gel blobs: 8

  • Gel Type
    • Selects the type of gel (Propulsion, Repulsion, Conversion, Cleansing)
  • Dropper Enabled
    • If checked, the dropper will spawn gel when active.
    • If unchecked, the dropper will disappear and it will place the selected gel on the ground where the dropper was.
  • Allow Streaks
    • If checked the gel selected can streak across the surface it hits.
  • Gel Flow
    • Light
      • Spawns a small stream of the selected gel.
    • Medium
      • Spawns a moderate stream of the selected gel.
    • Heavy
      • Spawns a large stream of the selected gel.
    • Drip
    • Spawns a drip of the selected gel every second.
    • Bomb
      • Spawns a large sphere of the selected gel that explodes on impact with a surface, object or player. Because this is an entity (prop_paint_bomb), it will also bounce off of faith plates.
  • Start Enabled
    • When checked, the dropper will begin spawning the selected gel when the map is loaded, and stop when activated by another test element. When unchecked, it will remain off until activated.


When selecting a gel type from the menu, a gel blob appears that can be placed on surfaces. Once placed, the associated gel dropper will automatically be placed on the next available surface above the gel blob. Dragging the blob around will move both the blob and its dropper. To only place a gel blob without its dropper, the automatically positioned dropper can be selected and deleted separately.