Noritake EX3 firing parameters

[ICONDENTAL]

Hi Icon,

we oxidise at 980'c for 5 mins in air and then re-sandblast. We don't usually get tension cracks, however, sometimes there are cracks that are being caused by the bubbles in the porcelain.

I got my colleague to build up another Argipal bridge today, and again she had no problems. I spoke to the UK argen supplier who told me that Argipal is ok to use with Noritake but I wouldn't like to swear that they are right. There seems to be no info in the Noritake instructions as to the cte range of the ceramic which unusual.

Today I'm casting with a new crucible and Argilte 80SF+

Also will help if you purge your ovens and pegs etc..

 

[adamb4321]

this are theparameter for ARGIPAL and for ARGILTE 80SF+
Oxidation Procedure:for ARGIPAL
650-1010°C, hold 5 min, remove oxide

Oxidation Procedure:FOR ARGILITE 80SF+ 650-1010°C, hold 5 min, remove oxide, no vacuum

When you said that your college build another bridge , did she used Noritake?
the fractures come from diferent directions , such as over glazing which will also make your shades not to match 100% one way to fix fractures is to Grind "V" shaped trough along the crack, fill in with porcelain and refire.and the bubbles could be due to Unclean metal , make sure there is no trace of investment and when you clean prior to degassing use distil water and also no air-house it. let us know how is it going and if you could show some pictures of fractures and bubbles so we can have a visual.

Hi,

Just double checked, we are oxidising at 1010'C not 980'C

Yes, she built up in Noritake with no problems.

The only other thing that I've changed (but this change is pre noritake) is from using a slab to a wet tray system. I have no issues building other porcelains eg Duceram Kiss, Cercon kiss, E.Max Ceram, Vita VM7 etc and my colleague also uses a wet tray. I've built up a couple of units today but used the wet tray, I'll see how they look on glazing.

If I get any more bubbles I will take some photos, I would have done it already but it's been manic here.

Thanks for you suggestions!

 

[lcmlabforum]

Switch out your wet tray from hers and see if it is still the same pattern . . .

 

[adamb4321]

Right,

I've been through as many of the variables as possible.

I had a single central that was done as a biscuit bake come back for glazing, you guessed it... Bubbles, so had to re-do.

Stripped it off, no bubbling in opaque layer. Re blasted and opaqued, built it up this time I used a solid mixing palette and the Noritake forming liquid (usually I use water, yes out of the tap) First fire looked good, nice clarity. Trimmed the ceramic, and it needed some small additions.
Built up the additions as normal (this time I fired the additions at a higher temp than usual) looked ok after firing until I started to trim. Micro porosity was present, I trimmed off the porous ceramic. At this point I had a minor epiphany, I use a heatless wheel for my initial trimming (contact points etc) whilst my colleague just uses diamonds. Could my use of heatless wheels be the problem?

I thoroughly cleaned the trimmed ceramic before re-doing the correction firing. This time it was almost perfect (just a couple of tiny bubbles probably from the 1st porous correction firing) I trimmed the crown and glazed as usual.
This time no more bubbles and the crown looked good.

I'll have to experiment with some other units to see if the heatless wheels are causing the problem, but at this stage it looks favourable.

 

[Bob Wall]

I switched to Noritake EX3 maybe 6 months ago, I keep getting a recurring bubble problem that can range from very minor to bloody major.

I've been through all of our processes and tightened up on our sandblasting blasting and opaquing procedures which has helped but not eliminated the problem.

The porcelain looks good when fired with nice clarity/translucency but after glazing has either micro porosity or big surface bubbles, crowns that have had additions are affected the most.

I keep thinking it's under fired and that's what is causing the problem (I've already increased the firing temps about 20'c over the Noritake recommendation) but it looks like its fired properly.

What temps/parameters are you all using (furnace is a Zubler) for Noritake and do you think the suggested firing temp for additions is to low or ok?

You are adding too much opaque on the 2nd bake. Just be patient do 4 separate bakes thin layers with the opaque brush. Noritake opaque acts differently depending on metal type and will begin to bubble on itself and create bubbles in your porcelain becasue you went with the traditional 2 bake and done opaque application. If you go 4 bakes and paint it on conservative it holds up nicely

 

[adamb4321]

Hi Bob,

I ended up binning the EX3 and changed over to GC Initial, such a transformation. The best ceramic I've used, lovely to handle and the clients love it too, I've found with custom shades we are more likely to match it the first time, which is nice.

 

[desertfox384]

Hi Bob,

I ended up binning the EX3 and changed over to GC Initial, such a transformation. The best ceramic I've used, lovely to handle and the clients love it too, I've found with custom shades we are more likely to match it the first time, which is nice.

I tried GC for a few weeks in December. Great porcelain. Will switch from Inline soon, however I do not like their paste opaques.. dry out in an hour and I'm told they cannot be rehydrated. Haven't tried the powder opaques, I'm hoping those are better.

 

[adamb4321]

We don't have many problems with the paste opaque and I'm sure we've diluted some of them before, probably with the Noritake paste opaque liquid. I find generally that paste opaques do not improve with being squirted into a palette and left, some of them seem to absorb moisture out of the atmosphere and get thinner whilst others dry out. We tend to just expel enough for which ever unit we are opaquing