fusing wire into glass without it being capped

[glassy]

I plan to create a fused glass piece that has copper wire as its inclusion. I have used copper in my previous work but I always cover it with a clear cap. Do I have to cap it? If not, will the copper stay slightly above the surface? I am afraid to experiment! I need advice from someone who has done this. I want the copper to act like a subtle barrier defining the various shapes and colors of each glass (ie.: a white house having a light blue sky and green grass). Any suggestions?   Thanks!