The other day I took the MBRPs out of the matchboxes and heated them with HCL and boiled them for a while. After they cooled down, I drained the HCL. Then I washed them with acetone twice. They are completely dry now. However, the color of my MBRP is not completely red. I can see the RP with a little blackness. What are these blacknesses and do they cause any problems in RXN?