Nathan at Noodler's likes to experiment, if you hadn't figured that out already. One of his creations is something he calls 'waterase' ink, it's a wet erase ink meant to be used in highlighters or marker pens on dry erase boards. He introduced it at the Boston pen show last year. Here's a video he made on it:
As soon as I found his video a couple of months ago, I talked to my distributor about getting this ink. Nathan basically made one batch as an experiment. I did have a few people asking me about it, so I picked up what was left of his test batch recently and I have it available in blue or black if anyone wants any. It's $19 for 4.5 ounces and comes with a free Preppy highlighter. Just email Rachel if you're interested.
I don't think any more of this ink will be made unless there is a demand for it, as Nathan pretty clearly states in the video. What's your impression?