bullseye v tekta fusing temperatures

Started by shafeenan, January 17, 2015, 11:34:09 AM

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shafeenan

I'm very new to fusing and have been practicing on tekta glass (cheap) but now want to start fusing some bullseye.
I've got the fusing temps just right in my SC2 for the tekta. So I need your experience - will bullseye need higher temps?
Also - if I fire 2 shelves, will I get the same results on both levels? and how much space would I need between the shelves - I only have 8 shelf props and 2 shelves!
thanks

flame n fuse

Hi Shafeenan
Tekta glass is made by bullseye. It's a bit cheaper than their other clear. Fusing temps should be the same.
I've never used 2 shelves in my SC2. I think you might have problems with uneven temperatures.
I expect there are others here who will comment on this.

jackiesimmonds

I was reading something yesterday...possibly on the Bullseye site but I am not sure...it clearly said NOT to use two shelves when firing glass, you will definitely get uneven heating in the kiln if you do.

shafeenan

thank you both - gosh but the file of info in my workroom gets bigger and bigger!

Nicknack

I've never tried 2 shelves, but was told that if  used in the SC2 that one would full fuse and the other would tack fuse.  When I got my Fusion 10 the lady I bought it from let me have a second shelf, but said that when she had tried it, neither shelf fused properly - if one worked, the other one didn't even achieve a tack fuse.

Hope that helps.

Nick

shafeenan

Thanks - rather what I suspected, but had been living in hope!

Lakelady

I've tried two shelves - the only one that worked really well was a full B/E fuse on top and a float slump on the bottom...still experimenting.  Have fun!
Turner Rowe Glass Art

Zeldazog

Tekta glass is the same formulation as Bullseye, the difference is that Tekta is machine rolled which is why it gets that really smooth side, whereas Bullseye is hand-rolled

I have successfully fused over more than one shelf, but only in a tall ceramics kiln, with only four shelves and large gaps between the shelves.  Even then, I'd put tack fusing on the bottom, and full on the top - great for a class where everybody wants different results!


jackiesimmonds

surely a lot depends on where the elements are?   For a kiln with elements right at the top, in the lid, two shelves would mean that the top shelf is near the elements, hence the full fuse for the top shelf and a lesser fuse for lower shelves.  But if you have a kiln with side elements, wouldn't that be quite different?

shafeenan

I believe the SC2 has elements only in the sides so would assume that if one had two shelves the top one would be hotter as the lower one would be 'shadowed' by the upper and thus maybe could full fuse on the top shelf while tack fusing on the lower. I ws thinking I might give this a go, but suspect I'd need ore shelf posts to raise the second shelf above the 1inch that would otherwise be possible with the posts provided with my second shelf!
Have to say that in my whole one month of learning about fusing, I'm so grateful that this craft seems to have so many helpful artists willing to share their hints and tips.

anditsinthefish

I have used both shelves and tend to get similar results on both. I have more of a difference between whats in the front (tends to tack sometimes) and whats at the back (full fuse) but I have a bead door so this could be why.

Sarah xx
Sarah xx
Website. Blog. Flickr.

Zeldazog

Quote from: jackiesimmonds on January 19, 2015, 08:09:00 AM
surely a lot depends on where the elements are?   For a kiln with elements right at the top, in the lid, two shelves would mean that the top shelf is near the elements, hence the full fuse for the top shelf and a lesser fuse for lower shelves.  But if you have a kiln with side elements, wouldn't that be quite different?

Yes, and no.  A ceramics kiln will have a series of elements up the sides, but heat rises, so it still tends to be hotter at the top than at the bottom.  At Uni, I made some ceramics wall art that was an assemblage of 37 different shaped 'tiles'.  Because it was terracotta clay, which goes deeper in colour the hotter/more heat work is applied, I had two choices - fire the kiln three times with all the pieces in the same position, utilising only one shelf.  Or mix up which tiles were on which shelf so that there was a subtle range of shades across the whole piece, such is the heat difference from top to bottom of the kiln (and in this case, I ignored the very top and very bottom shelves, only using the middle three and there was still a difference in temperatures, which we confirmed with the use of cones)

But you're completely right, a top elements only kiln will definitely have uneven heat with more than one layer of shelves.  This is why dedicated glass kilns are often larger area and flatter in design, so that everything is the same distance away from the heat source and only needs to be on one layer.


Interesting to read on the Paragon site, Sarah, this:

QuoteThe newest SC-2 has two separate heating elements in the left and right sides of the firing chamber. The back of the chamber has no element. Extensive testing shows that the heat distribution in the current SC-2 is more even throughout the firing chamber, because heat does not build up in the back of the kiln.

That reads to me as though they used to have a rear element too (which is what I thought they had and why I just went to check it out from Shefeenan's comment) - that, added to the heat loss of a bead door would definitely give you an uneven fuse.

I am sure I have read of others using SC2 two shelves and although getting a full fuse on both, one shelf is more rounded than another, I think that person planned on making two pairs of coasters, twice (so pairing the two top shelf ones, and two bottom shelf ones if that makes sense)


anditsinthefish

Quote from: Zeldazog on January 19, 2015, 06:23:28 PM
Quote from: jackiesimmonds on January 19, 2015, 08:09:00 AM
surely a lot depends on where the elements are?   For a kiln with elements right at the top, in the lid, two shelves would mean that the top shelf is near the elements, hence the full fuse for the top shelf and a lesser fuse for lower shelves.  But if you have a kiln with side elements, wouldn't that be quite different?

Interesting to read on the Paragon site, Sarah, this:

QuoteThe newest SC-2 has two separate heating elements in the left and right sides of the firing chamber. The back of the chamber has no element. Extensive testing shows that the heat distribution in the current SC-2 is more even throughout the firing chamber, because heat does not build up in the back of the kiln.

That reads to me as though they used to have a rear element too (which is what I thought they had and why I just went to check it out from Shefeenan's comment) - that, added to the heat loss of a bead door would definitely give you an uneven fuse.

I am sure I have read of others using SC2 two shelves and although getting a full fuse on both, one shelf is more rounded than another, I think that person planned on making two pairs of coasters, twice (so pairing the two top shelf ones, and two bottom shelf ones if that makes sense)



I guessed this would be the reason. In hindsight I shouldn't have got the bead door as I have never used it (I also have a maxine) but I could always look at changing the door. Or just adding to my kiln collection :P
Sarah xx
Website. Blog. Flickr.