I might some day try forging, but I’ll leave casting to the experts.
The reason to start with aluminum is the temp is way lower so it's much easier to build the furnace and the metal is cheap and readily available. You aren't wasting your time, since all the basics of mold design still apply such as controlling shrinkage and preventing freeze off. Paul's garage on YouTube has some excellent videos that cover the process in an instructional way, many of the other channels that cover casting just focus on the finished project. While very cool, these videos aren't always super helpful for a beginner. People also hate on the gingery books, but there is a wealth of super useful information there and the fundamentals haven't changed.
It's a super fun hobby, especially if you're already into blacksmithing. But do be careful and definitely heed the safety warnings, there is definitely the potential for an explosion or very harmful fumes.
Isn't 4th degree the last stop?
https://www.urmc.rochester.edu/encyclopedia/content.aspx?Con...
After burning through muscle and bone, there is not much beyond that to warrant another level in the classification.
In fact, some classifications just end in 3rd degree, and bundle muscle and bone damage in it.
This one goes to six: https://nigms.nih.gov/education/fact-sheets/Pages/burns.aspx
I'd wager that from a medical standpoint there is no functional difference between burning through fat layer, or going even deeper and hitting muscle and/or bone.
After bone its muscle and skin as it comes out the other side.
Metal poured into anything with latent moisture (damp ingot tray, etc) is a steam powered mini bomb with molten shrapnel.
Glass working, hot or cold, is much better for your mental health, it doesn't spit or stick.
Though I’ve seen people destroy their garage floor as well.
Edit: found a Hackaday article that covers this in more detail
https://hackaday.com/2020/12/30/water-and-molten-aluminium-i...
A classic video of the most common lab mishap with molten metals gets discussed to death here:
https://www.youtube.com/watch?v=KQjud8VCTYc
It's rare to find anyone who's ever done home casting that hasn't had a similar near miss at least once in their early days.
It's funny to look at .. but all it take to escalate is for molten drops to land on bare skin or flammable rags.
I came this close to setting my garage on fire, some old rags were stored in a box quite a ways off where I was welding something and a tiny bead of molten metal somehow made it in there and set the whole thing off. What still gets me is how fast it happened, and that I wasn't initially aware of what was happening because the fire wasn't emitting enough light to make it through my protective goggles (auto darkening...).
Lots of lessons learned that day, all is well that ends well but I'd rather not repeat that.
Also if you're going to bother to have a partner in such a situation, they should be touching safety equipment while you're pouring. I bet these guys don't even know where the fire extinguisher is.
Casting on a bench top to begin with isn't the brightest idea, you place your mold in the center of a concrete floor and you cast with something long enough to keep you safe, and you wear heat resistant aprons instead of lab coats. They got off very light, fortunately. I hope that they also realize they're out of their depth in the education department, because by showing this stuff to others when it does work they are passing on a ton of bad practices.
The same goes for a lot of videos and articles about home made batteries. I think I spent more time and effort on safety while doing my battery build than I did on the actual building and I'm pretty sure that if I had not that I would have had a real problem.
But casting metal and welding are still far safer than working on large Lithium-Ion packs in my opinion.