I've just completed my first fused piece......total disaster!!! I used some glass that I found which I presume is float glass.....it certainly isn't bullseye or toughened stuff. Anyway I put a layer of copper foil and then a small heart shape which I cut from some mica powder mixed with pva glue and then dried to form a film. Then another piece of glass on top. I now have what looks like a square fried egg! It has a HUGE lump in the middle.
Any suggestions?
Janey
Ok so not a great photo but here's the "mess"
(http://farm8.staticflickr.com/7329/10623807774_505a1edc4f.jpg) (http://www.flickr.com/photos/lemonkitten/10623807774/)
image (http://www.flickr.com/photos/lemonkitten/10623807774/) by lemon kitten 1 (http://www.flickr.com/people/lemonkitten/), on Flickr
I've never used mica powder, so I don't know what it's like for giving off gases, but anything that you use as inclusions that might give off gas can do this.
The glass has fused at the edges before the middle and trapped any gases given off by, most probably too much PVA. When I use it, I use a cocktail stick to dab it on, that's how small an amount you need.
The gas has then expanded, as it does, and stretched the glass whilst it was soft.
Look at the Bullseye Tip sheets for information about adding a bubble squeeze to your firing schedule. You can add little bits of glass at the corners to try and help stop trapped air.
Ah ha!! Thanks that's really helpful. I think i read somewhere about the PVA causing bubbles and I used LOADS!! to mix the mica powder. I will also re think my kiln schedule. I put in the basic slumping schedule and it seemed to fuse odd 104coe rods together quite successfully so I just used that schedule it also slumped some broken beads into cabs really well. Perhaps I need to tweak it a little? I'll also buy some bullseye glass...but I did read somewhere that you can fuse just about any glass.
Janey
You can fuse just about any glass together, but a full fuse will happen at different temperatures depending on whether it's Spectrum, Bullseye, Coe 104, float and so on. Just like boro takes far more heat to melt in the flame than normal soft glass, and I understand Bullseye rods take a little more heat that 104.
Float/greenhouse glass is great to experiment with as it's cheap, and you can often get it for free. Just keep a firing log, note down the schedule each time, and the results - and remember if you change glass, to think about the process temperature.
We are at Leek market tomorrow, come along and arrange to have some time with Claude
When I first started to try fusing, I used bottle glass being the cheapskate that I am. I still have some of the pieces to remind me of those times.
Have you tried using Flexi-Glass to mix with the mica? Once it's mixed, you can dry it on a perspex sheet, peel it off and then cut it inot all sorts of shapes. http://www.warm-glass.co.uk/flexiglass-and-sheets-p-3551.html (http://www.warm-glass.co.uk/flexiglass-and-sheets-p-3551.html)
Re my post above about using bottle glass, here's a fish bowl I made using bottle glass, both beer and wine bottle. The base was float. It's still whole many years later.
(http://pic20.picturetrail.com/VOL1426/5604171/24134598/408009382.jpg)
Wow Pat, that's really good. Whenever I try to use bottle glass for fusing (rather than slumping) it never manages quite to fully fuse no matter what temp I go up to or how long the hold is and I always get loads of devitrification as well. What's your secret?
That's beautiful, Pat! ;D
Quote from: MeadMoon on November 07, 2013, 01:57:40 PM
What's your secret?
Not sure I had one but I did all these in a big ceramic kiln with only a digital controller that had a soak facility. One slumped, I turned off the kiln and allowed it to cool naturally, about 12 hours. I did find that some bottle glass devitrified, usually some of the blues as in Harveys Bristol Cream but I had enough successes not to bother too much.
Ah, it's the blue from Harvey's that I've been using so maybe that explains the devit, but no matter what the temp/hold used, it only ever looks tack fused. Yours looks lovely and smooth.
Good advice above.
Suggest you work out the burn-off point for the PVA, and do a nice long hold just above there for a bit before you ramp it up further.