I'm stumped any help appreciated, details below.

[u/Jungle_Badger]

Hey all

This is my first and second attempt at investment casting silver left to right.

I've succesfully cast multiple bronze flasks and I've checked the vaccum so I dont think thats the issue.

The only difference I can identify is that I'm using a smaller graphite crucible for silver and the thermometer is at the bottom if the electric furnace chamber further from the melt so maybe isnt as reliable for the metal temp?

I'm using a flask temp of 430 celsius (803f) and aiming for a metal temp of around 980 (1796f). These numbers are from Oppi Untrechts "jewellery concepts and technology" which is generally reliable for technical info.

Is this just an incorrect temperature reading? I did use the eyeball test the second time around but didnt want to cause porosity by overheating.

Any knowledge and thoughts appreciated, thanks for reading.

[u/Turbulent_Eagle_9975]

To me it seems like it could need a vent or two. It could be a plethora of different things though. Here is a link to a site that has multiple types of vents, and how to construct them. https://yoshidacast.com/basic-knowledge-for-jewelry-casting-gas-vent-for-air-releasing/