To cap......or not to cap..???

[Bluebell]

Hi

I've another dilemma that I need your advice on.

I have some lovely etched dichro for making pendants. 

I originally fused a 2cm square (black backed) on top of a 3cm black opal square and capped with a 2mm clear which just overlapped the entire piece by about 1mm.  However, once fired (full, fast, up to 1480F (804c)) large bubbles appeared in the edges of the dicro. 

On asking what went wrong I was advised a few of things. 
1.  On a fast fuse, the edges of the cap fuse first, causing air to be trapped around the dichro.
2.  Any glue that I have used causes produces a gas which again can get trapped.
3.  Using a clear backed Dichro would eliminate the need for a cap.

So, I boughts some more of this dichro, but this time I bought clear backed.  I fired them on the slowest setting possible (took 17-1/2 hrs!!!), dichro side down, again at 804c with no glue.

This time absolutely no bubbles, but the dichro has seeped up around the edges and although I've seen it on loads of other's work, I don't particularly like it.  I like clean cut edges.  I really wanted a square black pendant with a smaller centred square of dichro but I have these horrible lines as well!

Should I go back to a cap and keep the firing on a slow setting - I'm informed this is a "bubble squeeze" or is there some other reason I'm getting this seeping problem?

[bluefairy]

how about putting clear strips around your dichro, the same depth as the dichro, then capping the whole lot? 

[flame n fuse]

or run some clear stringers out from the dichro square to the edge - helps the air escape.
Let us know how you get on!

[micpru]

Hiya,

How about just fusing the dichroic on top of a 3mm black piece and no clear top?  The dichroic will still look lovely.

What dichroic have you got - patterned, ripple,coloured?