Norton Flattening Stones?

I was looking at Norton Wetstones web site tonight and found this:
http://www.nortonstonesstore.com/Sto...loads/flat.jpg

"This stone is designed to maintain a flat surface on Waterstones. Waterstones get their fast cutting characteristics because they are softer than traditional sharpening stones. Because of this, they lose their flatness quickly. The stone comes in a plastic storage case with instructions."

http://www.nortonstonesstore.com/Sto...d&productId=42

Norton sells it direct for as good or better a price as I found anyplace else - Amazon, Woodcraft, etc.

Has anyone tried one of these for either initial lapping or reconditioning on wetstones? I'm thinking about what glass surfaces I have available to work with and wondering how I can be sure they're perfectly flat. Maybe using the figure 8 pattern on a glass surface with SC paper will equalize any irregularities so it's no worry?

EDIT: I just noticed that there's another thread on these, sorry for the duplication. I tried to delete this one but couldn't figure out how to do it.

Yes, I have one and it worked great. But beware of something...

When I got my new nortons, I used them, and lapped them regularly. After a perticularly heavy day of usage I lapped them. I was so impressed, I dug out one of my old barbey hones that was bowed beyond the point of usage, and lapped it flat. It worked fine, and then I discovered I had taken more material off the lapping plate than it did the stone!. So, only use it on the Nortons.

For the time being, I now lap with the back of the plate. I will get another soon, as it is very easy to use.

I am going to have to try one of those. I am sure my Norton needs lapping.

I've got one, and I like it, but for the same money (or less), get a glass plate and lapping compound. You can order all of it from Lee Valley Tools (and I highly recommend the mylar sheets to cover the glass plate), and it will get your stones much flatter, much quicker than the Norton flattening stone. With the mylar sheets, the glass plate is as good as the Shapton lapping plate, for about 1/10th the money. The glass, which you might be able to find at your local glass place (specify float safety glass, 1/4" thick minimum) is $10.50 at LV, the Mylar sheets are 10.50 for a pack of 4 (I've lapped mine dozens of times and haven't worn through even one sheet yet), and the lapping compound is around 6 bucks (90 grit...you can always smooth the stone out with sandpaper on the other side of the glass plate), It's easy, works beautifully, and Lee Valley has about the best service I've dealt with (damn those polite and professional Canadians :D) BTW, their U.S. distribution center is in N.Y., I think, so it won't take long to get your stuff.

I second the Lee Valley praise, awesome store.

As an alternative, you can also lap your 4k/8k Norton with a 1k or 1k/220 Norton. Works well.

Redwoood