Cheers, Paul. I hadn’t heard that about the investment residue. I’m off to scrub all my flasks!
I totally feel your pain and frustration on this one - I’ve been experimenting with Castable V1 and V2 for about 2 years now, and it’s only now I’m getting consistent results, and only after tweaking and trialing every stage of the casting process.
Here’s the document I found on plasticast. Step 6 is where it talks about degassing:
@katkramer, I’m 44m above sea level. I know what you mean - the weather changes quite a bit here on the east coast of Scotland, and I find my casting setup needs to be tweaked in Autumn and Spring. My big pump pulls at 12CFM, which means it creates a 99.9% vacuum in a 30L chamber in a little over a minute. Before buying a bigger pump or a small vacuum pot, you can try displacing the air in your current setup - e.g. if you have enough space in the bottom of your vacuum pot for 2 bricks, then put 2 bricks in there - the air that their mass has displaced is air you don’t have to pump out of your chamber, and should speed up your degas. Just an example, but you get the idea. I would definitely time your degas.