Yellowish Tint To My Crowns

[Mid-Florida Dental Lab]

All the sudden all the crowns fired in my Ney Cerampress Qex have been coming out with a Yellowish tint to them. I have Purged,Purged and RePurged but Im still getting that yellow. I know its the oven because when I use one of the other ovens the yellowish tint isnt there. If this has happened to you please let me know. Ive had this oven for years, its been great up till now.

 

[capickettcdt]

Sounds like Silver Ion contamination. I know that you said you purged...but how? the best is to go to a very high temp and hold it for an extended period of time. this will not remove the Ions but it will force them to the coolest spots in the muffle and in the firing block
( which is the farthest place away from the center of the muffle).
You might consider replacing the muffle and the firing block. It is more costly but also more successful. We looked chemically at some of the Purge products out there and did not see much difference between them and the high heat. Call us at 800-626-5651 and we will give you the purge cycle we use for the Whip Mix Furnaces.

 

[charles007]

What are you purging with ...carbon ... forget that ..
Use Purge-All and Purge -All Plus, including pegs and trays...
Use a non-greening modeling liquid also, since I'm sure your using a silver alloy .

 

[amadent]

What are you purging with ...carbon ... forget that ..
Use Purge-All and Purge -All Plus, including pegs and trays...
Use a non-greening modeling liquid also, since I'm sure your using a silver alloy .

thats from Vision USA

1 800 795 6199

 

[doug]

have you replaced the firing table yet? that may make a tremendous difference. not sure why but it seems that those things reach "critical mass" and are fine in the morning and have gone to hell by noon, never to be good again.

 

[charles007]

What porcelain and alloy are you using..

 

[DMC]

Too much Asparagus, or maybe you are getting sick.

Scott

 

[Tracy-zjk]

All the sudden all the crowns fired in my Ney Cerampress Qex have been coming out with a Yellowish tint to them. I have Purged,Purged and RePurged but Im still getting that yellow. I know its the oven because when I use one of the other ovens the yellowish tint isnt there. If this has happened to you please let me know. Ive had this oven for years, its been great up till now.

***Edited***

 

[Mid-Florida Dental Lab]

Doug....I just ordered a new firing trays and a platform for the oven in question yesterday. I'll let you know if it does the trick in the next couple days. Thank You

 

[Mid-Florida Dental Lab]

Charles.... I am using Synspar porcelain and Argelite 55 as far as metal. I also have used the none green liquidwhen it first started happening every now and then. It worked for a while but then,over night it just stopped working.

 

[Mid-Florida Dental Lab]

Cap.....I've been purging at 2000* for 15 min. with no vac

 

[charles007]

Cap.....I've been purging at 2000* for 15 min. with no vac

This is the old way we purged...order the purge all kit.. The contamination is not only on your plateform, trays, and pegs, its all in your mufffle..
If you move up to Avante, your shades will be 100% better, less shrinkage, but you will need to use Avante Modeling liq since the porcelain reacts to silver if though Pentron says different.

 

[Mid-Florida Dental Lab]

You know what we have a huge box of Avante boxes in the storage room opaques,incisals, and body with the modeling liq. I totally forgot we had it. As I was reading your reply out loud to a workmate, he reminded me of it. Once the new trays n platforms come in we're gonna start using it up. Thank you for the help Charles.

 

[charles007]

Years ago Avante improved their paste opaque... may want to see if you have the newer paste. I was told as it came out it would relieve the yellowing effect of silver.. Make sure you use their modeling liquid ! or you will see all B shades

 

[Mid-Florida Dental Lab]

Its from 2008 and the opaque is in powder form(i dont know if that matters)
I really dont trust the old liquid either so we ordered some today, honestly most the people in the lab just use distilled water instead of modeling liquid but as far as getting rid of the yellowing I've tried liquid and no liquid the only thing that helped was using a different oven do you think 08 Avante is OK

 

[charles007]

Powders are ok... order new liquid.. Avante is far superior