unwanted reducing in the kiln

[tammydownunder]

I would love to know why my kiln is suddenly causing my turquoise and sometimes bright lavender (272) to reduce when I anneal them. I put them in the kiln hot without any trace of reduction. It seems to be worse when I have them on the higher rack (made out of a mandrel). I have tried leaving the bung 1/2 open and full open with even more catastrophic effects. Would love to know your suggestions. That said.... I kind of like the etched look of the turquoise against the black.

[patienthand]

my memory is a little fuzzy, so this could be the wrong solution for your problem, but sems to me folks were putting some charcoal, like for an aquarium in the kiln to stop that.


another question, have you done any silver PMC in your kiln? I have a vague memory of it possibly causing issues as well.

Candice

[Trey Cornette]

Just saok those beads for 10 minutes in The Works or Sno Bowl toilet cleaner and you will never know there was any reduction on them. :razz:

[dusty]

You've got it backwards, Candice. They used charcoal to make it happen.

The reducing is likely because there's something organic inside the kiln - something that's eating the oxygen out of the atmosphere by trying to combust. If so, the solution is to give the kiln a good cleaning.

[PittsGlass]

Agreeing with dusty, we use charcoal in the annealer to keep our reduction.

Any new metal in the kiln? I had a similar problem when I used a non stainless steel mandrel rest. Must have been off gassing.

[tammydownunder]

Thanks, I will clean out the kiln and hope that's the problem.

[patienthand]

thanks for the correction.. I said my memory was fuzzy....

Candice

[PurpleCatJewels]

I'm getting unwanted reduction and changing colors, especially on turquoise and dark violet. My annealing temp is 960ºF average for all 104 COE. It doesn't matter if I put them in hot or do a batching later. Same scum.

Do I need to reduce the temp a bit to 940ºF ?

Or, how does one go about giving the kiln a good cleaning? Wire brushing the bricks? Just putting kiln wash over the whole shebang?

A year ago I did fire some glazed ceramic tiles in there and on another occasion used a "contaminated" fiber blanket (the fumes about killed me) for my beads. Wondering if the kiln is now kind of "dirty" from any build up.

Any and all help appreciated. Even though my beads are mostly UNDER 10mm, I don't want to NOT anneal.

[PittsGlass]

Don't wire brush the bricks. Remove your fiber blanket and replace it if it is warn or used during a contaminated firing. Vacuum out the kiln.

I also wonder about different batches of glass. Some batches are the same color but behave differently in the flame. I have one bundle of turquoise that just wants to get the grey coating on it, and another that plays very nicely.

[PittsGlass]

You can take one of those spongy sanding blocks (100 grit) and sand the brick lightly. Wear a dust mask. Vacuum out when done.