eMax Ceram on Zirconia - trapped gases

DevonR

DevonR

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Does your porosity just show up on the surface, or is it evident as you grind down?

Blow out your firing chamber and get rid of any dust.

Remove and clean out your vacuum line. Make sure you have a trap installed in line.


The porosity is just on the surface.

This is not a press oven so it only sucks air.
 
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The porosity is just on the surface.

This is not a press oven so it only sucks air.
I suspected it was a surface issue. That's why I made those suggestions. Moisture can collect in the vacuum line. When the vac is released, the moisture can turn to mist and instantly spray back into the firing chamber. Clean it and install a trap in the line.
valve.jpg
 
DevonR

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I suspected it was a surface issue. That's why I made those suggestions. Moisture can collect in the vacuum line. When the vac is released, the moisture can turn to mist and instantly spray back into the firing chamber. Clean it and install a trap in the line.
View attachment 27584


Hey, this is a possibility. Good idea. Is that just a filter from an air tool at a hardware store?
 
DevonR

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I fired a couple shade tabs, 1 from each furnace. Thanks Al

They are porous and 1 is noticeably yellow. So all furnaces are getting purged with fire trays and pegs. I'm cleaning everything.

I'll check for line filters next.
 
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Hey, this is a possibility. Good idea. Is that just a filter from an air tool at a hardware store?
I got it from Zubler.
Yes, its a foam filter. If your vac line drops down behind the bench in a U, install it closer to the oven, so the U is between the filter and the vac pump. Not too close to the oven...Half way between the bottom of the U and bench height. Any condensate in the line will collect at the bottom of the U. The filter interrupts it when the vac cracks open and prevents misty air from back flushing into the oven.
 
Patrick Coon

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I would also check the quality of the vacuum to make sure they are pulling as required. With that check your vacuum hoses, as they can become worn over time and collapse during the vacuum draw, not allowing for vacuum to form in the chamber as needed.

I've also attached the two stage parameters for firing e.max Ceram. Use this for all dentin incisal firings, including any Wash firings you do. Normal firings for Zirliner, stains and glaze. This program was developed to help with the surface porosity some people saw (kind of like yours).

Remember, with low fusing porcelain like e.max Ceram, a rough first firing is normal. After smoothing and shaping the first fire, any additions and subsequent firings will be much smoother.

Not sure if we've talked, Devon, but give me a call if you want. My number is below.
 

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  • emax Ceram 2 Stage Firing Program.pdf
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Contraluz

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I've also attached the two stage parameters for firing e.max Ceram

I would try these parameters. On top of it, I keep the vacuum through the full cycle. Try it, you will like it... :cool:
 
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are you using a round or square brush? :) ( no **** got asked this once by rep after contacting their expert when I had similar issues!)

Allot of what your trying is Voodoo I think (we all been there). 2 stage firings, different liquids all that stuff.You didn't say whats going on with your vacuume? your getting proper vacuume? and how much? the whipmix has a way of checking this??

almost certainly not related to yours but I spent years fighting similar surface pitting. In the end it turned out it was contamination from using blue rubber wheels for smoothing surface before final glaze fire. Didn't matter how well was cleaned. Stopped doing this (went to using sand paper cones) and all my problems went away.

using distilled water/build liquid/glaze liquid in ceramic depending what I'm doing.
770. (even higher if your firing on trays and not on pegs)
vacuume- start 650c, through rest of cycle.
about 4-6minute dry,
lisi or emax ceram no different (I use both on the same crowns)

Do that, if you still having issues its the furnace. temps off, vacuume not working properly, needs dehymidifying or a clean cycle to burn all the crap out.
 
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DevonR

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are you using a round or square brush? :) ( no **** got asked this once by rep after contacting their expert when I had similar issues!)

Allot of what your trying is Voodoo I think (we all been there). 2 stage firings, different liquids all that stuff.You didn't say whats going on with your vacuume? your getting proper vacuume? and how much? the whipmix has a way of checking this??

almost certainly not related to yours but I spent years fighting similar surface pitting. In the end it turned out it was contamination from using blue rubber wheels for smoothing surface before final glaze fire. Didn't matter how well was cleaned. Stopped doing this (went to using sand paper cones) and all my problems went away.

using distilled water/build liquid/glaze liquid in ceramic depending what I'm doing.
770. (even higher if your firing on trays and not on pegs)
vacuume- start 650c, through rest of cycle.
about 4-6minute dry,
lisi or emax ceram no different (I use both on the same crowns)

Do that, if you still having issues its the furnace. temps off, vacuume not working properly, needs dehymidifying or a clean cycle to burn all the crap out.


Yes, the furnace is our newest one. But i did do a vacuum test and it doesn't drop a pinch of air. I have the vacuum start at 450 and release 15 seconds into the 1min hold.

The pitting happens from the 1st bake so I haven't ground anything yet. But thanks for the blue wheel tip.

I'm gonna continue to fool around with it after a few other tips here and if that fails, I'm gonna take Patrick Coon up on his offer.
 
Patrick Coon

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Yes, the furnace is our newest one. But i did do a vacuum test and it doesn't drop a pinch of air. I have the vacuum start at 450 and release 15 seconds into the 1min hold.

The pitting happens from the 1st bake so I haven't ground anything yet. But thanks for the blue wheel tip.

I'm gonna continue to fool around with it after a few other tips here and if that fails, I'm gonna take Patrick Coon up on his offer.

Just let me know when, so I can arrange to be out of the office! ;):D
 
JMN

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Did you put your oven into the mode to test vac level? Most of them have a way to see what it thinks the vac is pulling on a second by second basis. Your vac may need new seals or hose connections if you are certain the hose is good.

Something odd, and it may just be my overactive pattern recognition filter, but in the picture you put at the top of the thread. Look really close. It looks like straight lines intersecting to make a diamond/rotated square pattern. Is there any way possible that helps??

Edit: I know I can't draw, but it gives the idea.
File 2017-09-15, 10 15 34 AM.jpg
 
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Patrick Coon

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Something odd, and it may just be my overactive pattern recognition filter, but in the picture you put at the top of the thread. Look really close. It looks like straight lines intersecting to make a diamond/rotated square pattern. Is there any way possible that helps??

Wow, JMN! You must see patterns in just about everything! :)
 
rkm rdt

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image.php
 
Contraluz

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don't think so.. it's pretty consistent through the different shades

Seriously, try the new firing parameters and/or hold the vacuum throughout the full cycle, and that means trough your holding time at end-temparature. I had the same issue, and many other techs, too, and holding vacuum resolved it pretty much!

M

Edit: You my want to modify your moist control, too. Seal the model before applying ceramics. This will give you much better control of your moist level than letting it absorb through the model!
 
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Did you inspect your Emax coping well? Could there be porosity I your emax after pressing


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Does your furnace open far enough? You could get "burning" on the surface if your crowns aren't away from the direct heat. Remember when you fire an all-ceramic tab your temperature should be 60 degrees Celsius or 140F higher than your first bake high temperature


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