More Red Ink Appearing

The last couple of mornings First Born has been waking up with read ink spots on his face.  I don’t know if the mattress never dried from the sleeping with a pen fiasco or if the humidity is bringing up the ink again.  Either way he will be sleeping with a towel under his sheet until I can figure out a way to permantantly get rid of that ink.  Anyone know how to get ink out of a mattress?