Hi, S. What you are calling "fake" brick is probably firebrick. This is made from some special clay that is high in kaolin. It has some sawdust mixed in with it and when the bricks are fired, the sawdust carbonizes to leave small voids in the brick. The voids act as insulation. Water will degrade the performance and you could have a lot of problems if there was still water in your firebrick when you lit the first fire. Spend your time cleaning around the fireplace. The inside is supposed to be black and sooty. Santa Claus will be disappointed if it is not when he visits.