It might be. I've only used the Mapei from Lowes,but they don't carry it here anymore so I have to find another. Seems buying grout online would be expensive with shipping

Actually, it's not that expensive (may reserve that thought; however, when it comes). I ordered it along with some diamond-shaped tiles from Mosaic Tile Mania. SH was just $6.00. The jar says it's 1 pound, though. That's probably not much. It's supposed to be for glass. I like to get diamond-shaped tiles from here to make flowers. So far, this has been the only place I can find pre-cut diamond shapes.This is a partial pic of a gazingball I'm working on. I love to use these shapes.
Jeanette

Here is a link that might be useful: {{!gwi}}

Is that unsanded grout or a specialized grout?

I buy my black grout from Home Depot - closer than Lowes - sanded grout - & it's very black.

No, I haven't but I have ordered things from Mosaic Tile mania and been pleased with what I got. The 1lb bags don't really go to far but are perfect if you just have one piece you want to grout.

When i first got started(not that long ago) I bought a bunch of 1lb bags from various ebay sellers and got some cool color.

Good luck

I only use Glass Pro black raven grout with my glass-on-glass mandalas for over 15 years. I have never had any issues with it. It is a nice charcoal black as opposed to a midnight black. You can see the results on my website. Art Glass Mosaics by David Chidgey