How to avoid kiln debris? and how to prevent kiln shelves from staining when using cobalt blue?

[Gazal]

Hi 

Does anybody know how to avoid kiln debris?

Also when I fire pieces which are painted in cobalt blue or royal blue under glaze, somehow the bottom of top shelf gets stained (let say if I paint a plate in blue flowers I get the same image on the bottom of top shelf of where the plate was located in the kiln) and then when I fire a white/plain piece that stain from the shelf transfers to my ceramics (not like a perfect image but more like some dots or a big stain), so basically I'd get blue stain every now and then on my ceramics even when there is no royal blue colored pieces are in the kiln. Does anyone know how to avoid it?

Thank you

[neilestrick]

Can you describe the debris? If it's white chunks in your glaze, it's either kiln wash flaking onto your pots, or bricks flaking. Does it only happen on the top shelf? Is there any wash on the bottoms of your shelves?

You can't really stop cobalt from fuming. You might try putting more space between the top of your plates and the bottom of the shelf above them. I've never heard of it fuming the bottom of a shelf, so I think it's just too close.

[Babs]

Vacuuming the kiln thoroughly after each firing and checking edges of shelves and underneath each shelf as removing from kiln helps. How are you storing your shelves?

O you have kiln wash on undesides or edges of any shelves?

Top or front loading?.top, vacuum top edges of bricks carefully before starting your load.

Is your kiln brick or fibre? Electric or gas?