Gold Casting help

Hi, I am working on making a couple of wedding bands for our wedding and ran into some questions in the process. Perhaps someone could help. I already have a burnout kiln, and a vacuum caster.

1. I plan on melting the gold using a torch. Does it matter what type of torch I use? I already have a basic MAPP torch from Home depot. (yellow bottle). Can I use a acetylene oxygen torch, or is the MAPP torch enough? Someone also mentioned that I could use pure propane and oxygen or hydrogen oxygen. Any suggestions?

2. There are some torches/hoses/regulators for sale around me. Are all these parts interchangeable, or can you only use acetylene torch for acetylene, and propane for propane, etc..?

3. At first I was considering just buying all the metal separately and alloying myself, but then I learned that it would be better quality if I purchase gold casting grain. Then I learned that I could either purchase alloy metal grain and add pure gold, or a fully alloyed grain. Does it matter which one I purchase?

4. I read an article online that says that you need to buy the appropriate alloying grain based on how your melting your gold/alloy. The article is called When Bad Things Happen to Good Metal by a website called jewelrsalloy dot com (I can't post links yet). Can anyone elaborate if this is true, and how much of a role is it going to play in my situation? What is the best alloy grain for alloying 18k light yellow gold using a torch?



5. Last question. I'm kind of confused about how the vacuum casting machine works. The vacuum seems to be generated against the sides or bottom of the investment plaster. There doesn't seem to be any holes leading to the actual mold hollow space. So how can a vacuum affect the hollow space if there's no connection between them? Does the investment have some tiny holes that the vacuum seeps through? Very confused about this.

Does no one have any experience with casting here? :(

Well yes there are some, but maybe they are away or unwell.
I presume you are going to cast rings with a special design, or texture. Otherwise obviously, it would be much simpler to bend them up from wire.
Hopefully a member will pop up with an answer for you. Dennis.

I use propane and an oxygen generator in my torch. But I melt metal electrically. Personally I would buy the grain already alloyed if you are not familiar with making it gets very expensive quickly. The investment is porous allowing the vacuum to pull the air out of it. Depending on the machine you are using you can get perforated flasks that work a bit better but need to fit into the machine not just sit on top of it. Different gasses have different regulators so fittings will be different threads are also different to stop you fitting the wrong ones too.