Still hot. But tonight I welded up the next five. These ones I left the hot rolled surface. My cost was just over $3.20 each. My time about, 20 minutes each. I guess it is time to leave them out in the 1’ of snow. Then start pouring aluminum and copper.
Perhaps some, uh, mo(u)ld wash with a high percentage of graphite? Graphite, denatured alcohol, and shellac for a binder?
Soot or rust! Ya shouldn't need any release agent if you have draft. I pour bronze in 1/4" thick steel. As the bronze cools, it shrinks. I just flip them out.
Sooo...like I have access to all sorts of little pans. I planned on using a single serving round dish for mine. Would fit nicely into my crucible and I figured I could stack them about four or five high inside it. I realized that I got one that was already heat treated after weeks of sitting outside and still no rust.LOL
Ironsides linked to a Youtube video where someone cast a rectangular iron ingot mould with maybe 1/4" thick iron that cracked on the first pour of aluminium so grey cast iron may not be able to cope with the expansion. I gave up on using those small round dutch ovens I found and have just blasted and seasoned them with oil in the oven.
The ingot trays that I made work like a charm for aluminum. They work mediocre for copper. At the beginning I was spraying graphite lubricant on the trays and pouring into them cold with the aluminum. It didn't make much difference the process graphite versus non-graphite, as I was dipping the tray and ingot into a bucket of water 5 to 10 minutes after pour. The aluminum pretty much just jumped out of the tray. The trays got a small surface rust. Nothing extremely deep as I store them in my air-conditioned shop. When it came to copper I poured some straight into Cold trays. And I painted some of them with some old Motor oil (just with a paintbrush). I also dip, tray and ingot into a wheel barrel water bath. The oiled trays popped out a lot quicker, but they smoked a lot more for 10 minutes before the wheel barrel bath. The hot trays get rid of a lot of H2O really fast. The surface rust is minimal with both my polished and non-polished trays. One thing is that I noticed, when the tray was hotter during the second pour (with the oil brush), there was less bubbling on the backside of the (tird) ingot.
Me? I'm still here every day once or twice. I'm getting ready to put my big boy pants on and go for cast iron in the next month or two. What do you think? Old dumbbells are they cast iron? I also have a few brake rotors that I might monkey around with. I would like to compare the differences after melting and chill.
One way to find out... Hit those weights with a sledge. Now what is the quality of them, I have no idea. Someone here will tell you how to identify good cast iron from garbage.
The weights are probably better kept for ballast or mold weights, etc. because they're a good shape and they're clean. Plus who knows what's really in them. If you've got some time I'd keep my eyes open for bit n pieces that are already closer to crucible size that aren't such a bastard to bust up. I think your trade should lend to that. Cast iron is one of the holy grails here but nothing about it is particularly glamorous. If it takes more than a 3lb maul it's getting sawed which is a topic of its own. F that sledge hammer. Just my 2 cents. Pete
Good cast iron when broken will be a dark grey almost blackish all the way through with just very little white (chill) around sharp corners or edges. The more trashy the iron is the lighter it is and the bigger the white area becomes....not too mention lots of porosity and inclusions. On thicker castings that are not automotive it is common to find large internal shrink inclusions or blows that are not visible on the outside, but that does not mean the iron is bad...simply means they did not get the gas out of the mold cavity and it got trapped or they did not properly feed a hot spot and got shrinkage. This is a very generic way to tell about the quality...you can always add some steel and additives to get the iron right so unless it is radioactive iron I wouldn't discard it for being too trashy unless it is extremely obvious that it is full of impurities. You can also use ceramic filters if you feel the iron is too dirty.
I was thinking the same thing....my son gave some away a few months ago....before I realized I could use them.LOL
I've been plotting for a few years, now, to build one. Want better green strength in the sand at the places where I "do foundry".
Ive just recently been thinking about it. Was wanting some of our carbosand that we tried out here a few months ago as it does not need to be replaced after several pours like typical sand. This stuff never burns out...only the additives need to be replaced. It is extremely expensive though and they are not through with the trials yet. Soon as they do I am getting a couple of truckloads if I can. The only thing about it is it needs extra mulling when it is new....hence the thought for a really good muller.