Colour change of emax cad

[Jacob.smith]

Just wondering if anyone has had this happen.

I had an A4 LT emax cad full contour crown that i put through the crystal glaze firing, then did some staining and fired again on the crystal glaze setting. The crown colour was perfect so i applied a thin layer of glaze and fired again on the crystal glaze setting and the whole crown turned to about a C2/C3 shade. Even when i polished off the glaze the crown is still not the original A4 colour.

At the same time as the last crystal gaze firein i had 2 other emax crowns that i was glazing and they turned out perfect.

I am using a programat p500 that is very new (only fired about 10 crowns and all were perct and has been fine since)

Any thoughts

 

[mahill79]

Did you use the crystalization/glaze firing both times. after it is crystalized just use the regular glaze firing. like 750 degree C for one minute of something. crystalizing is at 850 for like 15 minutes.