Slumping question

[laurat]

Hi

i tried to slump a panel this week and it didn't quite work.

I used float glass and it did go the right shape but the edges were all wavey, not in an attractive way either just all over the place. and the edges of some of the coloured glass was a little bit crinkley and i had sharp edges that were not there before.

I am very disappointed as I really liked the desgin but now it looks a bit of a mess.

I know that it could be due to the high temp, but I am never quite sure which bit of the firin to change, the ramp rate ot the top temp? I don't have photos or the schedual with me as I am at work but I am sure that the top temp is 537C.

Many thanks

laura

[Zeldazog]

It would be more helpful if you could post the schedule, and of course a photograph, it might help us understand a bit more.

537 sounds more like the start of the annealing zone to me...

When you want to alter a process (i.e. you want to slump rather than fuse) you need to alter the process temperature - the rate is important, as the more you fire something, and the thicker it is, and the bigger it is, the slower you have to go, but rate is pretty much irrelevant if you over fire something.

[laurat]

Right the firing was

Inital Heat 538c/hr to 538c 0.00 hold

rapid heat process soak afap to 824c 0.20 hold

rapid cool anneal soak afap to 538c 0.15 hold

anneal cool 182c/hr to 427c 0.00

cool to room temp afap to 25c


I am struggling to get the photo onto this laptop as it is a bit wonky.

but all adice is very welcome.

laura

[Zeldazog]

Yikes!!

Please have a good read of the Bullseye tech-notes before you do anything else.  See here:  BULLSEYE TECHNOTES - The Heat & Glass #4 is particularly helpful as a starting point.

I know you're working in float, but if you take a look through some of these, you'll see your firing schedules are way out.  I generally full fuse my float about 30 to 35c degrees hotter, and slump about 20 degrees hotter than my normal Bullseye schedules.

• 538 per hour is far too fast IMHO.  I fire no faster than 266 per hour during the initial heat, as you risk thermal shock.  The more times you fire, the more important this is.
• 824 is a fusing temperature, again, WAY too hot to slump.
• Personally, I don't go any faster than 83c/hr through the anneal cool either, but especially larger plates and panels, I definitely wouldn't.

I'd say no need for the photograph in all honesty, it's definitely been fired too hot.

[laurat]

Thanks for your advice

I will have a look and see what changes I can make.

I will report back and let you now how I get on.

Laura

[♥♥Tan♥♥]

What thickness of glass are you firing?

[Flyingcheesetoastie]

Another thing i've picked up on in your first post is the two different glasses, you mention float and 'coloured glass', is this float compatible or are you introducing further problems by using different glass that isn't compatible?

Hope that makes sense, compatability is a major factor in any kind of glass melting.

[laurat]

Hi

Its a sheet of 3mm clear float glass with compatable coloured glass on the top.

I have slumped a 3 mm sheet of bullseye glass with randomly placed bullseye glass on it, this time it did stay in better shape but it seems that there was air trapped between the glass and the mould. I check the air holes in the mould and these were clear. Itlooks like the temperature didnt reach the same high as the other side. I was thinking that i may try and slump it again.The annoying thing is I really like the design!

Thanks for all the help, I really appreciate it. I have the ideas but the firing side is leaving me stumped!!

[Flyingcheesetoastie]

So you used the programme devised for float glass on a bullseye glass firing?  Or you did a different firing with the bullseye glass?

It sounds like your learning loads by trying different things out and getting unique results, which is the best way to learn!

Keep at it and we'd love to see pictures of your creations too!

[laurat]

I used a different schedule for the bullseye - I learnt very quickly that different glass needs different temps!

I have kept a good record of what I have done and taken lots of notice of things said on the threads here.

How often can i reheat and mould the glass?

I amgoing to take a load of photos next week and have a go at flicker too.

[laurat]

I have done it!!!

Thanks to all your advice I have what I consider to be an amazing dishy!


Cherry Dish by lilacstars, on Flickr

[Aurorabelfast]

Love it!!

[laurat]

I have a poppy one to slump this week.

Its addictive!

[Les]

Brilliant ! I love poppies ... I even named my daughter after them

[Pat from Canvey]

Well done. I love poppies too, lets see the pictures.