>Yes, I had heard that you can irretrievably adulterate a coffee machine
>such that it can never be used for coffee any more if you put CLR in it.
>(But it definitely burns off all the limescale in minutes)
The active ingredients seem to be lactic and gluconic acids (to
dissolve the mineral deposits), and lauramine oxide (a surfactant).
I wonder whether the residual taste from the CLR is due to CLR
residue, or whether the CLR attacks and alters the surface of the
metal enough to cause it to start "leaking" metal ions into the
water. The latter could lead to a pretty nasty taste, and subsequent
cleaning of the coffeemaker wouldn't help.
>No one seems to have come across a CLR alternative (of which there are
>MANY) which doesn't do this.
For filters and other reasonably small, removable elements, I wonder
whether putting them into an ultrasonic cleaner, with water and a
small amount of a neutral surfactant, might not do the trick. This
might remove the mineral scale buildup through an essentially
mechanical process, rather than a chemical one, and wouldn't attack
the surface of the metal with chemicals that could alter its surface
chemistry and cause it to "leak" ions.