BruxZir issues

MrMolar

MrMolar

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Hello all! Hoping someone can help me out here.

Our BruxZir is being cantankerous lately. We have 2 ovens that we use, one being new-er, about 600 hours on it, i'd guess.

We normally fire our bruxzir in the older oven, but they had been coming out pitty. so we switched them all to the newer oven, and they're all pitty and green looking. we run a purge cycle on them once a month (1600C for 8 hours) and they have been fine. now we're having some green tint to them.

Any ideas on what to look at? Currently running a cycle with some sintering beads in there.
 
CoolHandLuke

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sounds like you already understand furnace contamination, i'd next look at the shade liquid application technique (ensure you are not applying with a metal tipped brush) and examine the beads themselves. they should be changed every so often because they do also become a source of contamination.

then i'd check that the zirconia itself isn't being contaminated by being bathed in an ultrasonic that has been used for other things.

then examine your glasses for anti blue glare coating.
 
MrMolar

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sounds like you already understand furnace contamination, i'd next look at the shade liquid application technique (ensure you are not applying with a metal tipped brush) and examine the beads themselves. they should be changed every so often because they do also become a source of contamination.

then i'd check that the zirconia itself isn't being contaminated by being bathed in an ultrasonic that has been used for other things.

then examine your glasses for anti blue glare coating.
wait. people use ultrasonics for crowns? I had no idea that was a thing. all of our zirc is pre-shaded, which is notorious for gasses being let off.
 
JMN

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then examine your glasses for anti blue glare coating.
This is a huge thing that is missed. that and the 400um range anti UV coating that is available now.
 
CoolHandLuke

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wait. people use ultrasonics for crowns? I had no idea that was a thing. all of our zirc is pre-shaded, which is notorious for gasses being let off.
our customers usually do wet milling with few exceptions; even though its just water from the tap, it can be useful in many cases to remove hard water, or minerals via an ultrasonic cleaning before drying. especially in lead or heavy water, or counties in the USA with poor quality tap water.

but i mean, ultrasonics on green state zirc can be bad if they also use the same tapwater or arent cleaned after every use.

this is the primary reason some opt for dry milling. if the drying cycle introduced too much time, the cleaning cycle definitely introduces too much time.

but i don't know what gases you speak of in multilayer zirc.
 
MrMolar

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our customers usually do wet milling with few exceptions; even though its just water from the tap, it can be useful in many cases to remove hard water, or minerals via an ultrasonic cleaning before drying. especially in lead or heavy water, or counties in the USA with poor quality tap water.

but i mean, ultrasonics on green state zirc can be bad if they also use the same tapwater or arent cleaned after every use.

this is the primary reason some opt for dry milling. if the drying cycle introduced too much time, the cleaning cycle definitely introduces too much time.

but i don't know what gases you speak of in multilayer zirc.
from what I understand, the pre-shaded zirc, ML or not, produces a gas during the sintering process that can stick to the heating elements and get to a point where, once heated again, release from the elements or insulation and impregnate the crown making it a green/yellow color.
 

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