treating metal before opaque

[Edy]

i read on forums here on some thread that is better to clean the metal crown with an ultrasonic rather then with steamer , if yes why and with what material u pour in the ultrasonic , is it only water boiled or u put a material to clean metal better , and how much time u set the ultrasonic and what heat , i want to try that because my steamer has broken few days ago , oh , and after the ultrasonic cleaning u advice me to do an oxidation firing ? because i never did so far an oxidation firing for the last 8 months i am building porcelain ..

ty
Edy

 

[cheadlemick]

Haven't oxidized metal for 20 years, no problems whatsover but read the specs for your alloy, some need oxidizing for sure! You could just boil your copings in water or use chloroform to degrease the surface. Then a very thin wash of opaque!

 

[CatamountRob]

They all need oxidizing. With some it happens with your first opaque firing, others require a seperate firing.

 

[Edy]

They all need oxidizing. With some it happens with your first opaque firing, others require a seperate firing.

ohh , i see now ... since i started to do 1st opaque a bit thicker i get some yellowish color on the crowns , maybe i need to go back to make 1st very thin opaque , what about the ultrasonic ?

 

[CatamountRob]

I don't use a steam cleaner, I use an ultrasonic with distilled water. I put them in for about 5 minutes. Sometimes I get sick of the buzzing and take them out before the 5 minutes are up.
What do your alloy instructions say to do Edy? What alloy?

 

[CatamountRob]

The term PFM is sort of a missnomer, it would be more correct to call it a PFMO, as in "porcelain fused to metal oxide". Porcelain does not fuse to metal, it fuses to the oxide layer that forms. If the instructions tell you to do an oxidation firing, you should be. An oxide layer may well form when you do your first opaque firing, however the thickness of the layer is very important. Too thick and the bond between the oxide and metal can fail, when that happens, the oxide will be stuck to the porcelain. Too thin and the bond between the oxide and porcelain can fail, when that happens the porcelain that comes off will have nothing on the underside and the metal looks clean.

It isn't very complicated, just follow the alloy manufacturers instructions and barring some contamination issue, it'll work. Rob

 

[cheadlemick]

ok pedant no pre oxidization

They all need oxidizing. With some it happens with your first opaque firing, others require a seperate firing.

 

[CatamountRob]

Damn. I had to look up pedant.

 

[Edy]

I don't use a steam cleaner, I use an ultrasonic with distilled water. I put them in for about 5 minutes. Sometimes I get sick of the buzzing and take them out before the 5 minutes are up.
What do your alloy instructions say to do Edy? What alloy?

i use Ugirex III , its specified that oxidation not required , its has 62% nickel 26% chrome and rest is MO and Si which i dunno what it means , but will start to use my new ultrasonic instead of the steamer if its better that way and will put a thinner layer of opaque on 1st firing , because i am sure that i am getting the yellow colors on opaque 2 firing and even on the 1st bake of porcelain because i was doing a thick 1st opaque

 

[JohnWilson]

With all the metals in the world why would you use a metal that is 62% nickel?

 

[cheadlemick]

Damn. I had to look up pedant.

Lol i knew this forum was an education!

 

[Edy]

With all the metals in the world why would you use a metal that is 62% nickel?

because i am a newbie , why you think 62% nickel is bad ? actually 1 hour ago i got a problem with noritake ,i use UJIREX III, i started noritake CRZ for zirconia 3 months ago and was pleased of it , i got noritake EX3 few weeks ago , 1 hour ago i started to use it , made opaque paste of noritake and then 1st porcelain firing ,when i started to shape it with the micromotor with the green stone , after i just touch the crown a bit , parts of porcelain just fall down till metal , even the opaque fall down , and felt a strange smell of something like vinegar when the porcelain fell down , i wonder whats going on ... before this i used vita master vmk regular opaque not paste , and over it i built noritake and the bond actually very very strong , this time i used the noritake paste becuase i order C4 set .... maybe someone can help me, i will go to sand blast this and start again soon ...

 

[cheadlemick]

Use D.sign it bonds like "**** to a blanket" on all alloys that i have used!

 

[CatamountRob]

How much of a difference is there in the opaque firing schedules between the Vita and Noritake?

 

[Edy]

d-sign here in my country is very high price , and vita is very cheap and very good too , but this case i didnot have a vita C4 color , will get it asap , but meanwhile will retry the noritake , this time i will use my ultrasonic , i hope that my ultrasonic will work fine , its not a renfert one its a chinese , the porcelain maybe fell down because i just poured a boiling water over it because my steamer is in repairing place for last 2 weeks ... hmm , i just dont like when i waste time doing reworks which fail like this one ((

 

[JohnWilson]

because i am a newbie , why you think 62% nickel is bad ? actually ...

Well in my opinion if you are going to offer a NP crown I would not subject myself or my staff with nickel or BE alloys's its a health risk even when taking all the precautions when casting and metal finishing.

There are some fine inexpensive NP alloys that are both Ni/BE free, as for your bond issue what did your opaque look like after you fired it before you put you first bake of glass on? Any bubbles?

 

[Edy]

on vita is 1st firing is 960 with 80 rate , and 2nd 950 80 rate, noritake has 1000 , 65 rate1st and 2nd opaque , and what i heared that u can apply only one coat without a second opaque needed . . .

 

[CatamountRob]

You need one of the guys that uses Noritake. I think Charles and RKM both use it, or did.
If you are putting that much paste opaque on, it's probably going to need to be really dry before you fire it.

 

[Edy]

Well in my opinion if you are going to offer a NP crown I would not subject myself or my staff with nickel or BE alloys's its a health risk even when taking all the precautions when casting and metal finishing.

There are some fine inexpensive NP alloys that are both Ni/BE free, as for your bond issue what did your opaque look like after you fired it before you put you first bake of glass on? Any bubbles?

first of all ty for teaching me about risking for health , had no idea the nickel is so dangerous , when i ask my provider what i should ask him about ? just NI/BR free would be fine ?


And opaque was very odd looking after the firing , i was going to do one coat only without a wash opaque firing , that i learned from course of noritake i went to , so after it came out i saw some yellow coloring over the crowns , not all yellow but parts were yellowish and parts were ok , so i decided will do another opaque firing to cover this , after second firing all looked fine without yellow . . . then the porcelain just pooof jumped out at each touch

 

[cheadlemick]

In a Nickel Chrome alloy if there is at least 26% chromium it negates the toxcicity of the individual elements as in amalgam e.g. mercury and silver! However beryllium is a definite no no!