u/Puzzled-Marzipan-218

I am looking into getting a torch or maybe electronic melting kiln for casting. The head goldsmith at my work showed me a head for a little smith torch that is for casting. I am comfortable and familiar with the little smith, as it’s what I use at work. How viable is that option? I currently have an acetylene torch, and I’m scared to use as I am unfamiliar and don’t want to blow myself up. Are there any limits on quantity for little smith torch melts for casting? Specific aspects that a full size propane oxygen torch would be better for? My use will be one offs and will not be making large quantities of items with it

I am an apprentice goldsmith, with almost a year of experience. I am so close to having perfect resizings, but one tiny issue that continues to allude me is having porosity in my solder. I ultrasonic the rings, steam them off, and the sides are flush after they are sanded flat. I tried finding information specifically about porosity occurring in solder, but it was overwhelmingly about porosity in casting. What causes porosity, and how can I avoid it?