Magic Ink

Found at Spango's. A type of invisible ink. Write your message. Then place the paper on another written document. Say they command word and the original message disappears to be replaced by whatever was on the page of the other written document. Whenever the counter-command word is spoken, the original message reappears.
There is enough ink for about 30 messages or written pages. This ink is magical and could also aid in scribing spells. Using the skills of Aja and Falgrieg, there is a possibility of repurposing the ink.
Alchemy Craft skill DC 15+1d6 – repurpose the ink to a new command word. Failure will use half the ink.
Alchemy Craft skill DC 22+1d6 – figure out the original command and counter-command words. Failure will use half the ink.
Alchemy craft skill DC 25+1d4 – do both.