I haven't heard that an actual worm casting has to be processed again, but that vermicompost isn't 100% worm castings and that can be reprocessed through a vermicompost system in order to get a higher percentage of castings.

http://www.redwormcomposting.com/worm-castings/worm-castings-vs-vermicompost-whats-the-diff/

Makes sense as I've read that castings are actually toxic to worms, yet worms live in my harvested VC happily for months until I go through it again and rescue any who've been hiding. I think they are eating the VC that's there, there's certainly no non composted waste.

Think it's more of an issue if you try and sell it as 'castings', for putting on your garden it's all good :).

The ancient and secret methodology for determining if in fact a specific casting has passed through a worm several times was stored in the Book of All Knowledge. Unfortunately this book, which also contained detailed instructions on how to put a man on the moon, was checked out of the library sometime in 1973 and never returned.

We have instead used an alternate method for determining the veracity of casting proof of multiple passages by using an individual count and record method similar to that used to determine how many licks it takes to get to the center of a tootsie pop. This method so far has not been sucessful.

We are only able to determine that in the professional worm farmers opinion your (or any non professional worm farmer than him) worm's castings will never be of as high quality nor smell as sweet as his worm's castings.

This is due to the art of vermicomposting being something that only higly trained experts should be allowed to do. Don't try this at home folks.

LOL Thanks, equinox. That's what I suspected, but it helped to hear it from one of the lovely folks on this forum. :-D

Also, Peter, I appreciate the article. Thanks!

If you want some pure worm castings try placing a piece of wet burlap on the surface of your worm bed media. Cover the wet burlap with a sheet of glass and then some black plastic sheeting...trash bag works fine. In a few days the underside of the glass sheet will be covered in 'pure' castings.

To avoid a messy extraction process have several sheets of glass available for rotation. Let the castings dry and they can be easily removed with one of those worthless plastic auto window ice scrapers. Like Worms4Tracy comments I don't see any difference in the commercially sold worm castings than the 'spent media' (peat moss, coffee grounds, egg shells, and blended kitchen scraps) I remove from the tops of my indoor vermicompost bins.

I have a difficult time understanding why folks go to such extremes to removed worm castings only to reincorporate them into potting mixes, worm teas, and to be used as a fertilizer. I have used the grated 'spent media' for a number of years exclusively as a germination mix and incorporated into potting mixes, and it works just fine.