I did a quick search but could only find mention of people trying to use aliminium foil
under glass, where it bubbles A LOT and goes brown and yucky. Fusers seemed to have a little more success. My fuglies jar has a few beads with the texture of pumice where I tried to cover over aliminum and it just bubbled through, repeatedly.
I've been using it as surface decoration - you need to put it on a fairly cool bead or else the hot glass sucks it out of your tweezers and you get a blob or torn shape. Once it's on, just press it onto the glass with a metal tool and heat it up again. In the flame it webs a bit to give a nice lacy effect. I haven't tried to cook one excessively, but normal finishing off in the flame doesn't seem to bother it - I usually add dots of fine silver to mine afterwards. The texture on the surface is slightly rough, and the colour is a slightly matte silver. It seems to be very well stuck on - I've lost fine silver dots before, but not the aluminium foil shapes.
The hardest bit of this technique is getting the temperature exactly right before placement - too hot and the foil blobs, tears or bubbles. Too cold and it won't stay where you put it - though this is less of an issue, just put it in position, pat it down with your tool and carefully bring it up under the flame to warm up. As long as your bead is juuuuust warm enough not to crack when you put it back in the flame, it should work.
Here's an example, though the pictures came out a little bright...
https://www.etsy.com/uk/listing/387410602/lampwork-pendant-silver-butterfly-on 
