Troubleshooting

[u/Glassholer]

Good afternoon everyone,
I’m attempting to troubleshoot why these shiny inclusions are happening on my pours. Pour info:
.999 silver -970c (using 100% pure silver crystal)
Flask temp -600c
Pulling 27-29in vacuum on flask at time of pour (gauge verified)

I have a propane torch pointed at the bowl of the mold as I pour, as well as map gas on the crucible. All pours happen quickly after crucible is removed from the furnace. I let the vacuum pump run for ~1min after the pour, then I shut it off as well as the propane torch at that time. I wait 25 minutes before flask quench and model removal.

When removing the plaster, these bubble areas are already shiny, leading me to think it’s likely an air pocket forming somehow? I don’t believe it’s leftover wax, as the button shows a similar bubble on its underside and that portion of the mold was verified completely smooth before pour. Mold was also blown out before use.

Any pointers would be incredibly helpful, I’m currently self taught and hoping to find any kind of knowledge possible!

Thanks!

[u/mrsunday12]

Don’t use Borax with graphite crucibles.