Katana ML/HTML/HTML+ white spots

tehnik

tehnik

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Hi all!

I have this strange problem only with Katana strong material. I have had this problem since ML and now HTML+ is also having this. There are white spots on zirconia after sintering. These are not caused by sintering beads as the spots are on different places. As HTML+ has the same program as STML and UTML, I sintered them together and only the HTML+ bridge got the white spots. I have to grind them out as they are not only on the surface. Katana told to clear the sintering tray with compressed air as there may be some residue zirconia dust... even if it is there, how can it affect only one material? The trays are actually only taken out when the restorations are placed on them, all the other time they are in closed cabinet - away from zirconia dust.
 

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RileyS

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Maybe oil spray from high speed and it’s preventing coloration ? If dipping, maybe an air bubble on that spot, although I doubt that one
 
Car 54

Car 54

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Is it just from the 1 disc, has it happened with any of the other HTML+ discs?
Maybe it's just some schmutz in the disc itself?
 
C

CWilliams

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I don't use katana, but with zz pre colored I have to use a ceramic plate/ cover to avoid the potential of random white spots like your picture. With the cover, I don't get any spots.. why this happens I have no idea
 
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Nazar

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It can be because of moisture. Try to dry the block. Had similar problem with katana stml
 
tehnik

tehnik

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I am storing the blocks in the same room and condition. And as I said I am also sintering together. Using a cover sounds like a thing I should try, but for nabertherm sintering trays, I don't believe it is an option, at least for the larger trays. I don't precolor/dipp the restorations. The spots appear randomly - one job in one block and later there may or may not be the spots. Weirdest was a job where I milled 4 crown and all of them had one large spot on the lingual side in the middle.
 
Car 54

Car 54

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I have one disc that does have some sort of contamination, where I get small random white scale areas that can be ground out, almost like spots that don't sinter. Your photos and what you're describing is, looks, different than what I was experiencing.
 
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keroassidy

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Hi all!

I have this strange problem only with Katana strong material. I have had this problem since ML and now HTML+ is also having this. There are white spots on zirconia after sintering. These are not caused by sintering beads as the spots are on different places. As HTML+ has the same program as STML and UTML, I sintered them together and only the HTML+ bridge got the white spots. I have to grind them out as they are not only on the surface. Katana told to clear the sintering tray with compressed air as there may be some residue zirconia dust... even if it is there, how can it affect only one material? The trays are actually only taken out when the restorations are placed on them, all the other time they are in closed cabinet - away from zirconia dust.

Do you use sintering beads?
when we had this issue we would change out old beads. However we only use broken up pieces of
old zirconia pucks now and haven't had this issue since.
 
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Nazar

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You may store them in one room, but you don't know where they were stored before they got to you
 
Jenners

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I've had this same problem with Katana. It disappeared when we serviced the dryer for the compressor... so I'm pretty sure it's either oil from the high speed and/or moisture from the air lines. I used a brush instead of the air for a little while and the problem disappeared and hasn't come back up since we got dryer for the compressor fixed.
 
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Nazar

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Also can appear at some sintering programs. Like when you sinter at 1450 degrees everything is fine and when the temperature is higher can cause white spots. Some old heating elements can behave like this, so using the cover might solve the problem, cause small metal peaces will not fall on the work.
 
tehnik

tehnik

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I have two compressors both with air driers and they don't use any oil. The oven I am using for katana is less than a year old and the elements are in good condition. I will purge fire it at the weekend so it can be ruled out. As nabertherm does not have cover should I just stack another tray on top with the spacer?
 
tehnik

tehnik

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Update: I have used another tray on top with spacer and have had 0 problems with the white spots. Looks like it is caused by the loose insulation (thin dust) dropping down to restorations.
 

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