That is only with Sharpie markers the yellow turns read. I've found that the artist markers (Prismacolor)don't change colors under CA. I've tried all 24 of them. None of them change. With the Sharpie the yellow turns red, grean turns yellow, and dark green, turns brown. Get the Prismacolor markers off Ebay. The work great.
BTW, that lacquer will turn black with use. I used to use a very high quality lacquer for Behlen and it would turn black after a month of using the pen regularly. It is a reaction to the oils in your hand. They look great intially, but will turn. If you want to use lacquer an automotive lacquer might do the trick.
Very nice looking corn cob pen. I can't wait to turn some of my blanks. They are on the list.
John