Why are we seeing black "carbon like" specks in our fired porcelain crowns?

[Artexperience]

So after a couple days cleaning, replacing, making changes etc.........we may have come to the conclusion the contamination is coming from the vacuum to the porcelain oven. We see the black when we fire under vacuum, so far this is where I have stopped thinking. Has anyone heard of such a thing? Are the inside of hoses to the vacuum supposed to be cleaned? Wanted to put the thought and ? out there before the task of pulling the hoses off. If the contamination is coming from inside, where do we go next?

 

[JKraver]

... Is your vacuum pump installed backwards even if the tubes were dirty its pretty much a one way thing.

 

[charles007]

Wouldn't you know it, I read this thread yesterday and laughed. Haven't seen any black specks in upteen years.......
Yesterday afternoon I had a black speck to show up just below cusp tip on a nasty Noble pfm ... weird..
Guess that's what you get for being on dln to much

 

[DENTALWORLD]

We were using Vision USA's Purge All and or Purge All Plus until our oven manufacturer suggested NOT to use ANYTHING, just to run their suggested purging program cycle. So many differences in opinions as what to do and not to do in this line of work. I bet you could ask 25 lab techs the same ? and get 20 different answers

I use a product called sil-free and use there pins and don't have any black specks any more

 

[rkm rdt]

So after a couple days cleaning, replacing, making changes etc.........we may have come to the conclusion the contamination is coming from the vacuum to the porcelain oven. We see the black when we fire under vacuum, so far this is where I have stopped thinking. Has anyone heard of such a thing? Are the inside of hoses to the vacuum supposed to be cleaned? Wanted to put the thought and ? out there before the task of pulling the hoses off. If the contamination is coming from inside, where do we go next?

Are the vacs enclosed in a cabinet or freestanding under the bench?

 

[sidesh0wb0b]

I would agree, have your vents and ducts professionally cleaned.
the lab is a VERY dusty and dirty environment. keeping the vents clear of dust and debris is a MUST!

 

[Artexperience]

Wouldn't you know it, I read this thread yesterday and laughed. Haven't seen any black specks in upteen years.......
Yesterday afternoon I had a black speck to show up just below cusp tip on a nasty Noble pfm ... weird..
Guess that's what you get for being on dln to much

Funny, but not really. I think it's just a fluke, you won't see any more......

Are the vacs enclosed in a cabinet or freestanding under the bench?

Are the vacs enclosed in a cabinet or freestanding under the bench?

It is NOT enclosed, it sits on a tray on the floor under the bench. We have horse pastures below, outside the window. We have kept the window closed for a couple days now, trying to rule out the possibility of the jock sand dust. Never have we had this much of a problem, almost as if it has built up......

 

[rkm rdt]

They're sucking in metal dust .

 

[Artexperience]

... Is your vacuum pump installed backwards even if the tubes were dirty its pretty much a one way thing.

What do you mean when you say "a one way thing?"

 

[2thm8kr]

What do you mean when you say "a one way thing?"

Like an anus.

 

[Artexperience]

I believe we have finally solved the problem. Cleaning the vacuum pump and it's surroundings along with lifting it up off the floor, seemed to have done the trick Thanks for everyone's help, we really appreciate your time and responses! Have a great weekend all, TGIF