How to stop a Slump losing its slump!!!!!?????

[Flowers]

Hi Everyone
I'm a little stuck.
If I slump glass into a mould or over fibre paper more often than not it then needs to be shaped or sanded and sometimes I want to add to the piece.  But how do I do this without it losing the shape of the slump?
I tried an experiment yesterday a rectangle of tekta over 3 strips of fibre paper, put it in the kiln on a slump setting which was fine but then I neatened up the sides and added a few bits and put it in again (minus the fibre paper) on a tack fuse.  When I took it out it had lost the slump.
How can I keep the slump if I need to put my glass back in again? Should I keep the fibre paper in or do a different type of fuse what am I doing wrong???
Thank you so much

[Zeldazog]

Slumping is the lowest temperature of all the processes we apply to glass fusing (Apart from annealing that is) - so you have to do all your ful fuse, tack fuse or kiln carving first, before you slump.

If you've done a kiln carve (which I do at full fuse) and you find you want to add something, yes, keep the fibre paper in it as tack fusing is sitll quite hot.

Take a look at this from Bullseye, it explains what happens at each temperature range very well


https://www.bullseyeglass.com/methods-ideas/technotes-4-heat-a-glass.html


On the subject of slumping, assuming you mean into a mould (if you mean using fibre paper, that's really called kiln carving or bas relief - slumping just means softening the glass enough to bend, not to reshape) - some people will combine slumping with fire polishing, but in my opinion and experience, all other processes are too hot for slumping, and your glass will deform as it slips down the side of the mould. 

[Zeldazog]

I am guessing you're using presets on your kiln.  Take a look at what those schedules actually are - the temperatures that is programmed in.  It's worth getting to know them as this should explain why your slumps are disappearing at fusing temperatures.

Even better, get off presets, and learn to program in yourself, you will have so much more control over what you do, a much better understanding of the process, and it's essential if you want to start creating mulit-layer or more complex, thicker designs.

[Flowers]

Hi there thank you both so much for your kind advice.
Thank you for the link to settings I will print it out and have a look.
So kiln carving should be done on a full fuse rather than a slump setting?
And basically slumping is the very final stage of a piece?
Also what exactly is a fire polish?   

[Zeldazog]

So kiln carving should be done on a full fuse rather than a slump setting?

Well, you can do it on any setting you like, but the hotter you go, the more definition you will get.  There's another Bullseye tipsheet about kiln carving, and you can see the sort of detail on that, they recommend at least full fuse.

And basically slumping is the very final stage of a piece?

Because slumping is the lowest temperature process, yes - when planning on making a piece that might have several stages and different process temperatures, you have to consider what temperature each will be and design your work in that order.

Also what exactly is a fire polish?   

Fire polishing is taking the glass hot enough for the surface to melt slightly, so that it softens and smoothes.