Zirconia going yellowish!

[Mona Lobsey]

Does anyone have this problem before? I am using "Mihmvogt" Sintering furnace for about 2 months and never used Colored Zirconia in it, and i am experiencing a very bad yellowish color since the beginning on "DetalDirekt" Zirconia Crowns! I tried to sinter other brands than DentaDirekt and the results are just the same
I emailed the company but they said that is because the furnace still new! Does that make sense? All of my work is yellowish now and i am still waiting till the furnace will become old! Help please!!

 

[NicelyMKV]

Need to run your oven up to 1600c and hold for two hours.


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[Marcusthegladiator CDT]

CONTAMINATION.

 

[Mona Lobsey]

Thank you so much! I'll try that tomorrow. I wonder what is the reason for the contamination knowing that it's a new furnace! Can it be that the boy who is handling the zirconia is doing something wrong? Can it happen to the zirconia itself before centering or it's from the furnace itself?!

 

[sidesh0wb0b]

i had some sintered Zi go pink when rubber wheeling it......never seen that before. its happen 3x now, but not on all crowns

 

[Marcusthegladiator CDT]

i had some sintered Zi go pink when rubber wheeling it......never seen that before. its happen 3x now, but not on all crowns

The pink/brown is only on the surface. A very light sandblast will remove it.

 

[Marcusthegladiator CDT]

Thank you so much! I'll try that tomorrow. I wonder what is the reason for the contamination knowing that it's a new furnace! Can it be that the boy who is handling the zirconia is doing something wrong? Can it happen to the zirconia itself before centering or it's from the furnace itself?!

Are your sintering beads and trays yellowing too? You may need to replace them.

 

[sidesh0wb0b]

The pink/brown is only on the surface. A very light sandblast will remove it.

yes I determined that. doesn't seem to effect anything, but what is causing it?

 

[Mona Lobsey]

Are your sintering beads and trays yellowing too? You may need to replace them.

No i didn't use the beeds yet. I have them but i don't know what do i need them for as the fit is good so far.

 

[dmonwaxa]

Someone on DLN mentioned in a previous thread about this. It's possible the acid based stains is causing it, so a decontamination cycle should help.

 

[grantoz]

acid stains and not drying the copings out will contaminate the job very much.I was in china checking out the opposition you should see how much their furnaces are contaminated that's why they like emax because they cant afford or don't want to pay to keep things clean.

 

[LA Ceramics]

So are you milling with sintering pins then? I hope you aren't just laying them on the tray,... cuz,.... hmmmm....

 

[Techy]

What Nicelysaid....ramp quick to 1600....hold
do this at least once a week

clean those elements,,,,that oven should not need a "break in" period
We love that beast!

 

[NicelyMKV]

I have been running my Mihm Vogt 5 to 6 days a week for a few years now. Never had one issue. I was told by ZublerUSA to ramp to 1600 and hold for 2 hours awhile back. e everything look even better than it already did. I do it once a week now.

 

[Mona Lobsey]

So are you milling with sintering pins then? I hope you aren't just laying them on the tray,... cuz,.... hmmmm....

I'm actually just laying them on the tray! Do you think that is the problem? I don't really know that sintering pins are, will you say more about them plz!

 

[Mona Lobsey]

Need to run your oven up to 1600c and hold for two hours.


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It didn't help

 

[NicelyMKV]

It didn't help

, are you sintering at 1450c? Any way you could post a pic? I think I have an idea


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[Mona Lobsey]

, are you sintering at 1450c? Any way you could post a pic? I think I have an idea


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[Mona Lobsey]

White crown has been sintered in another furnace. The bad one is mine and supposed to be bleach! And I'm using 1450c

 

[digvijay]

check the settings and sinter at recommended temperature as given by manufacturer,
i have been using different sintering cycles for different zirconia and even for copings i do different cycle , full anatomics , translucent and bridge work also i have different cycles ,
once i brought a chinese blank for that i have a manufacturer recommendation of s2 temperature to be 900*celcious for an hour then s-3 at 1540 *c , but the crowns came out so beautifull that i need not to do anything , it can be hand polished and sent.
maybe you are not using beads and discolored beads also impart color to zirconia, check it.
all the best.