CONCRETE INDOOR FIRE Use up your wax scraps in style with the purist indoor concrete fire, which is lovingly handmade in our Krefeld factory. sustainability The indoor concrete fire is equipped with a special permanent wick which, when used correctly, barely burns and does not have to be replaced for a long time. It is necessary to add wax approximately every 3 — 4 hours (depending on temperature, type of wax and wick length). The wick consists of many, extremely thin, individual glass strands. These do not burn, as you would expect from conventional candle wicks. The fire can therefore be refilled with wax over and over again. The flame of the concrete indoor fire is similar to a candle. It does not produce more soot than a conventional candle. Therefore, it is ideal for indoor use. The wick stands below the wax surface in a metal structure that prevents the wick from buckling when adding wax.