Hello from the UK. I have done one successful cast with my son for his GCSE art project, so I now want to move forwards into new realms of angels and demons. Made from beeswax and modelling wax. I am planning to cast straight from the originals, have no idea how to sprue, how thin we can get the wings how to make a shell. Got a bucket of Wexcoat and two home-made furnaces, some silica bronze. Wish me luck! I am hoping you guys are here to help. PS I am not a complete noob as I have a lot of experience in ceramics, building kilns etc. but never done metal before.
Getting bronze to flow any length of distance at anything less than an 3/16" thickness is tough. Remember the thinner or farther you go, the hotter your pouring temp. Getting something to accurately measure your metal temperature will go a long way for you. Pour too hot and surface finish goes to hell, pour too cold and the shell won't fill. I just winged it for a few years, got lucky most of the time, but measuring your metal's temp is a smart idea. And I'm not talking about a point and shoot meter either. They are simply not that accurate. I know you are in the UK, but mifco sells a probe you can stick on a 5dollar meter that is extremely accurate. https://mifco.com/shop/pyrometers/replacement-8-thermocouple-tip/ I'm not a fan of dinking around with molds either and like to roll the dice with originals. Just do it smart, you'll shed less tears.
