Thermo Liners

Here is a step-by-step guide as to how to custom-mould heat-formable liners from your ski or high altitude mountaineering boots.

You will need:

  • An oven. A fan forced electric oven is best. Avoid gas ovens. For regular convection ovens see footnote¹.
  • Thin ski socks.
  • A wooden board. About 20–25mm thick.
  • An old hiking sock to make a toe cap. Cut these off just in front of the ball of the foot.


  1. Pre-heat the oven to 110°C.
  2. Remove footbeds and laces (if applicable) from the liner.
  3. Put heat-resistant baking paper (e.g. GLAD® BAKE) on a tray and G-Fit liners on the paper. Place in the oven for 12–15 minutes.
  4. Put toe caps on your foot and thin socks over the top.
  5. Remove the heated liners, reinsert the footbeds*, and put on your foot.. Leave the laces off.
  6. Slide the liners into your boots with care to not create any folds as the liner will be soft. Do the buckles up with moderate pressure only. Not as tight as for skiing, just firm. Make sure the liner tongue is seated centrally.
  7. Stand in the boots and rock gently back and forward and side to side to seat the liners correctly. If the shell has a forward lean this should be locked in place.
  8. Place toes on the board to give a little extra pressure on the shins and stand in a relaxed position, knees slightly bent, for 10 minutes while the liners cool.
  9. Do not use the boots for at least 2 hours after this process.


NB: Heat-mouldable liners may be thermofitted up to 5 times. They must be completely cooled before attempting to thermoform them again.

*Performance footbeds such as Superfeet may be used with the liners.

¹Convection ovens. Pre-heat to 130°C, then switch off. Allow 3 minutes to cool and then place liners in the oven as instructed above but leave the oven off. This eliminates the possibility of radiant scorching.



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