Mike..i don't think it's necessary to remove the lining inside the bottle.i have a feeling the Swiss thought this through very well,like most things they do,and made bottle with a coating that soldiers could heat without any ill effects.whatever that stuff is it will not come off in boiling water.even the torch had little effect on it,i had to hold the flame in one spot for minutes to get any results.the boil test over the backyard burner was also long,i boiled away half of the water and the parts both in and out of the hot water showed no change in color and the coating could not be scraped off with a knife point after being in the hot water.after the bottle was cut there was no way to peel the coating off by getting a knife point between the aluminum and the lining,it's bonded right on.