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Cold spots in kiln - usual or unusual ?

Hi All I've been using a little Paragon SC2 front-loading kiln for the last 6 weeks or so - mostly making small fused pendant pieces, dichro, earrings - that sort of thing.

I'd noticed that not all of the pieces in each firing were fusing fully - and recently seem to have discovered that the 'bad' pieces are located at the front and right side of the kiln.

Things came to a head the other day when I tried fusing a large piece of glass (well - 5" diameter - which is large in relation to the size of the kiln). The left side of the piece fused well - but the right side was less well fused.

I wondered if there was a problem with the kiln door not closing tightly, and tried, on the last couple of firings, to introduce a 'gasket' of fiber-paper around the door - not sure yet if it makes any great difference. Paragon say that the door gap is to allow for expansion.... and suggest that I 'bring the glass up slower as to heat soak the ware to it maximum'

I guess the question I'm asking is - 'Is it normal that you get hot / cold spots in a small kiln like this ?' If it's normal, should I simply increase the time at the top temperature so that the 'cold' spots get hot enough to fully fuse - it's a pain and time-consuming at the moment to have to re-fire pieces that didn't work the first time around..

Any sugestions welcomed Thanks Adrian

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Reply to
Adrian Brentnall
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Try approaching the top temperature and/or soak a bit longer. Then note if the "hot" side is overdone.

Reply to
nJb

Thanks - I'll give that a try. I'm currently soaking at 820c for 20-30 mins - guess I could increase the time a bit. As pieces are fine after a 'second go' - I suppose 40

- 50 mins would be a good starting point..?

Thanks again Adrian ======return email munged================= take out the papers and the trash to reply

Reply to
Adrian Brentnall

That should work but it does seem odd that the fusing would be that uneven. Often I soak at a lower temp (1480F-805C) for an hour.

You might want to see this:

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Pages of good info here:

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And the best fusing forum on the net:

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Reply to
nJb

Thanks - I might give that a try...

I found a bit in Petra Kaiser's book - suggested that a possible problem with small kilns like the SC2 is that they heat up very quickly (compared to a large kiln).

She points out that the thermocouple measures air temp - not glass temp - so even though the air might be at a good 820c then glass may not have caught up quite.

Your plan of 'cooler for longer' might be the solution - I'll give it a go ....

Many thanks Adrian

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Reply to
Adrian Brentnall

Yes - understood... all part of the learning process

Adrian

Reply to
Adrian Brentnall

Hey Guys, This post from Dec. 1st has shown up on my news reader as new today even though I have already read it and deleted it before. I have been noticing this problem lately on my groups. Has anyone else had this problem? Are the servers burping 8-}

Reply to
C Ryman

Go down

wrote

Nope, mine still says it was posted on 12/1/05 must be your service or your reader, gathers it after you delete, why not let the reader delete it on its own when it gets too full?

Reply to
Javahut

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