Discolored Zirconia after glazing

[FASTFNGR]

Has anyone who uses emax glaze paste and or spray experienced your zirconia crowns turning black after glazing? I ran a cycle and they came out black. Any idea why this happened? If I try to correct will it work or should I just mill again?

If you grind the glaze do you get back the original color? If you do then it is the glaze. If not, issues could be with sintering temp or coloring if you dip.

 

[rkm rdt]

Change labs

 

[sirmorty]

I would also try a different firing tray.

That one you are using is for Emax CAD sintering. It's probably eating of alot if the heat and it's metal.

 

[TheLabGuy]

Yes, this happens to me every once in awhile with e.max glaze and I didn't give it enough time to dry before it goes on the heat cycle just like contraluz was eluding too. Just sandblast it off and reglaze, add a few mins dry time and you'll be fine.

 

[drforbesdmd]

Yes, this happens to me every once in awhile with e.max glaze and I didn't give it enough time to dry before it goes on the heat cycle just like contraluz was eluding too. Just sandblast it off and reglaze, add a few mins dry time and you'll be fine.

thanks!

 

[Patrick Coon]

Yes, this can happen with any glaze. All glaze pastes, and glaze powders mixed with glaze fluid, and to a lesser extent sprays, have organic materials in them to keep them from drying out while you are using them (glycerin and other materials). So does peg putty. If these do not fully volatilize before the vacuum comes on then they will leave a gray hue, black streaks, or even a black crust on the crown. (looks really gnarly).

When using the pre-programmed ZirCAD glaze cycle on your CS furnace it is assuming that you are using the minimum amount of putty, putting no more than six units in to fire, and not over applying the glaze. If you do any of these then all the organics will not volatilize before the vacuum comes on and will settle in the glaze. This can be made worse if you try to use the speed program (which greatly shortens the dry time),or created your own program with a short dry time, fast rate of rise, low vacuum start temp.

Not sure if you did, but I would also recommend if using that tray, that you use the pins as well, and only enough Object Fix (peg putty) to hold it on the pin without the pin touching the crown. This will pick it up off the tray (which is designed to capture and hold heat for e.max crystallization),and allow the e.max crown to heat more evenly. Yes if you are using the honeycomb tray you could place it directly on the tray, as those trays are designed to heat up and cool down quickly.

 

[Patrick Coon]

One more thought, since it is zirconia, I would also recommend the Crystal Glaze Past Fluo. Will still have the same properties I spoke about above, but will add some fluorescence to your restorations, so they don't look lies us folks from Mississippi when they go to the club!

 

[Sda36]

One more thought, since it is zirconia, I would also recommend the Crystal Glaze Past Fluo. Will still have the same properties I spoke about above, but will add some fluorescence to your restorations, so they don't look lies us folks from Mississippi when they go to the club!

Thanks Patrick for mentioning this, low fusing inherited a bunch of issues never even considered with higher fusing ceramics. Sadly it's a big thing that must be considered. Glad you shone a light on it! ( The Grey Narley Result) if you don't take this into consideration. No, I'm not wrighting a poem on "Consider" this!