Cracking tabletop veneers

[wwcanoer]

Doing a tabletop veneer number 19, shade A1, stump shade N D7. Remember correctly, the guide suggested pressing out of HT BL 1, but I thought it be too bright, so also pressed out of HT A1.

Was able to finish the veneer pressed out of HT BL 1, but both veneers that I pressed out of HT A1 cracked in half after cooling from the glaze cycle. I'd say this is a pretty ideal prep, definitely no sharp edges to deal with. The crack ran buccal to lingual. These two veneers were not touched with a carbide bur at all. None of the veneers had any type of layering done.

So the question is, why didn't the HT BL 1 veneer crack? Or why did the HT A1 veneers crack?

Thanks

Carol

 

[Ryan Gottlieb]

Can you post a photo?

 

[wwcanoer]

 

[RDA]

Are you using an instant refractory material to hold these while glazing? If so, I've had the same problem, but only with the instant peg form Vacalon. Try a porcelain pillow, that is what helped for me.

 

[rkm rdt]

So that's what a tabletop means.

What a crazy prep design.

 

[Brett Hansen CDT]

We have gotten cracks in our e.max's from time to time as well. I believe too rapid cooling/heating can make these more likely in certain crowns.

 

[wwcanoer]

using "custom-peg putty' from hankins

will try cooling on next

thanks

c

 

[ps2thtec]

using "custom-peg putty' from hankins

will try cooling on next

thanks. (QUOTE)






Why not just lay it on the honeycomb tray; skip the putty. I stain/glaze most that way. You could double stack
the tray to get the height up. .
Could also be a Thick Thin issue?

 

[wwcanoer]

Success, finally!

Ran through the glaze cycle, with a long cooling, and without peg putty. Came out in one piece!

Thanks everybody!

Carol

 

[Polarmolar]

How think is that Veneer?

 

[wwcanoer]

at the crack, thickest 1.8mm, thinnest is 1mm