I've been watching some YouTube videos of guys pouring ingot molds. They pour it, pop it out on a block of ice, touch it to a wire wheel and they have a perfect shiny casting worthy of being sold at weatherbee's. Is it massive amounts of experience? Creative editing? Or magic? I have rough finishes, large crystal growth, concave surfaces, pits and fold creases.
That's what commercial bronze and brass ingots look like from the supplier. You can minimize the oxidation by not having any molten metal exposed to air, i.e. the sand mould has a lid on it. The ingot stacking guys on Youtube would be sanding a large portion of their ingots off to get a good finish and you never see that in their videos. Most of their copper and aluminium ingots show signs of porosity and defects even after polishing.
No magic, little experience, lots of grinding and editing, and staight up bullshit. Clean melts, clean metal, temp control, etc can minimize the effect, but physics and chemistry dictate the outcome. A closed mold will bring you worlds away, but minor, and sometimes gross defects will still occur. Refining of technique to minimize that is a good percentage of what we talk about here. Someone listed a group of top-shelf YouTube casters here recently. Those are pretty much the only ones I'll watch. The "personalities " and guys who wear shorts and flip-flops are out. Pete
As the guys have said, open ingot casting is rarely nice on the top. It has to be hot enough to flow and cool as possible. Skimmed just before pouring. Reverse your patter and pour with the face against the sand. The back may be ugly but you'll get a better finish on the face. Or as Pete said, go ahead and make a proper mold with a parting line (your pattern can all be in the cope) so you have sand all around and you'll start learning how to cast metal. Trying instead of talking is key to learning. Guys here will help but you learn more from failures.
The Texas castings are in an open cast iron mold. The brass with all the trash on top was necessitated by virtue of running out of propane, I could skim it and have a solid chunk of brass in my crucible or I could pour it with the trash.
I didn't understand. So you have learned a lot, about sufficient fuel and the value of skimming. For brass it is also very valuable to have a brass flux to avoid making a lot of dross. The more melts the more dross. I missed that you were using a cast iron mold, I thought it was a cast iron pattern. Not sure I'd preheat it. Pouring ingots into steel molds I've had the ingot weld to the mold when everything was really hot. To get it out I had to drill the mold so I could get a punch on the ingot. Easy to weld up a steel mold. I use a Budget Casting flux: https://www.budgetfoundrysupply.com/brass-bronze-copper-flux Copper phosphor shot is good to make the melt more fluid but you shouldn't need that yet. If you can move to sand casting it really opens up your options.
To get 2 nice flat sides you could maybe sand the nasty side of one of one of your open pours down smooth (and to desired thickness) and use that as a sand casting pattern. Jeff
Thats what happens with molds open to the air. Thats why you always pour with a sprue or feeder channel that leads from the pouring cone to the part to be cast because the part that is exposed to air rarely comes out looking nice but everything below it looks better. So you position the part you want to look nice at the lowest point knowing the shitty parts will be at the top. It is sometimes possible to get a clean open mold pour if you skim the hell out of the metal before pouring and you pour the metal as cold as you can while still keeping it liquid. Then it doesn't contract as much when it cools and doesn't form tears in the metal or have dross stuck in the surface.
I'm actually going to make my sand casting boxes tonight. I'm actually growing kinda fond of the brass with the trash, it kinda has some character
It can be nice if you sand blast it clean so the color evens up. I often use the left over metal after I pour the left overs onto sand for sculpture bases. Lots of character for sure. But cleaning it up to be smooth is a lot of hard work and sanding drums.
Unfortunately at this time I have no access to a sand blaster. Tonight it's going to have a bath in a 50/50 muriatic acid/ water mixture
It's surprising how small of a compressor you can get by with as long as you are prepared to work slow. My 4gal compressor delivers 3.5CFM@90/4.4CFM@40 and using the el cheapo HF sand blaster it will blast for about a minute or so, then I need to pause for the compressor to catch up. It's slow going, but most of what I use it for are small parts which don't require a lot of time. Sooner or later I'll get a better compressor, but until then I'll accept slower work over no sandblasting at all.
You can get one from horrible freight for maybe 140 to 180 depending on coupons. Or on Facebook marketplace or Craigslist.
