toilet rail blistering

[appreplumb]

I recently installed a new towel rail and as soon as i fired the heating up the towel rail started to get small blisters all up the front of it. Does anyone know the reason that this happens?

 

[Caduceus]

Some "chrome" coatings are actually like a heat-tape coating and exposure to heat will blister it and make it peel away from the surface. True chrome plating of a metal (brass) rail will not peel away, but a brass towel rail will be much more expensive.