What is crowning a fret? - just that :)

[Redeye2]

I'm gonna level my frets and I saw something about "crowning" the frets. What's it?

Also, where can I get some oil to seal a fretboard I plan to scallop? thanks.

[Rich]

The crown is the arch it takes to the peak/top of the fret. When you sand or file you're making the top of the fret flatter, which makes where it meets the edge sharper. You're just putting the arch back on.

[Josh Blagg]

You'll need a fret file to recrown your frets and you have to be precise in order to get really good intonation.