I recently set up a casting studio after a long hiatus from making jewelry. I was given a Victor Oxy acetelyne torch with a standard pointed tip for melting metal, mostly silver. I am getting a lot of porosity in my castings. The last time I can the pieces looked almost like filigree. I used silver with a deox alloy. I believe that the problems are being caused by the acetelyne torch. Does anyone have any suggestions, should i use a rosebud torch tip? Is propane better for casting?