I would like to try casting and am considering zinc or pewter. I have searched the net and have found volumes of information on aluminum casting, but good zinc casting information seems to be elusive. I have used google with various search parameters and have found a few PDF documents. Can anyone direct me to any websites or books that contain good and up to date information?
Zink is not used much in backyard casting because it burns. The fumes will make you sick. You would need a cover flux to keep air off it while it is molten. There are better choices for most cast items, few things need to be zink.
Do some searches for ZA-12, ZA-25, and ZA-27. Zamak, as well. These are Zinc-Aluminum alloys that are used a lot for home casting, in sand and permanent molds.
These alloys melt at low temperatures, are cheap, and machine well without heat treat. They also work very well as a bearing surface. They flow well, take good detail, and generally don't have too many obnoxious things about them.
You WILL want to have a pyrometer to monitor the temperature so as to be able to pour at the lowest temp that proves to work for the castings you want to do. If you overheat any zinc bearing metal, it will fume off the zinc into the air. If you find yourself having breathed these fume, drink milk to offeset the effects of zinc fume fever.
It's easier than aluminum because it has a lower melting point (watch out, don't overheat and boil it) and being denser, flows well. Pure zinc is useless but potmetal (zinc with usually aluminum 1-27% and a few points of copper) is very strong. Same advices apply.
Actually, due to the low melting point, you don't really need a furnace. If you have a good stove you may be able to do it right there.
I know lots of folks who would rather make zinc castings than aluminum as its easier to work with and easy to scrounge up. It will only bun if its overheated smae as any other metal will also get ruiined by over heating. Visit my website:
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Thanks to all who replied. This newsgroup is a never ending source of valuable information on a variety of topics. I am most likely going to try to cast zinc alloys as I am just getting started/learning about casting and all of its intricacies and given zincs low melting temp and properties is sounded like a safe(r) place to start. While searching the net I found a few melting pots for low temp metals and was wondering if one would be worth investing in? Or would an elecrtic stove/hotplate and a pyrometer suffice? Concerning "fume fever" I have read that the effects are unconfortable but do go away, but are their any long term effects? I looked it up in the Merk Manual and it has little information other than it is caused by zinc oxides and that it can cause neurological damage. Other sites I have visited says that it does not cause harm other than making you feel ill.
I would suspect the melting pots are geared towards either solder (soldering circuit boards etc. en masse) or lead (for casting bullets). If it's the latter, it *might* work but probably won't get hot enough to reproduce fine details. A hot plate might do it if you add some firebrick to hold in the heat. You really need fire for this, but not to the extent of aluminum or bronze.
Just today I melted some zinc in a tin can held over my medium burner (.035" orifice I think) at maybe 5-10PSI, took 15 minutes for maybe a pound. Open air, not really any insulation at all. Real wasteful of fuel, mind you. It'd be faster on a good charcoal fire, no need for forced draft. Just pile the briquettes up around the can on the grill.
Not that I know of. Probably why you can't find any information on it. :^)
Even so, I've been soldering since 9 years old and I'm perfectly healthy. I've never been much for good ventilation or washing hands or anything, mind you. Lead isn't a problem, stay out of the exhaust at least (which is common sense anyway) and wash your hands after handling it if you're really worried.
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Why not start out with Pewter, which is readily available in sticks and has a low melting point. Since modern pewters are almost pure tin with some antimony, they don't pose the same health hazard that Zinc fumes are reported to here.
You can make your moulds from RTV rubber, Look up Tiranti on the web
If you are just starting out, I would try using whatever melting equipment you have available in consideration of the casting size you are making. For example, there are small ladles made of iron, that could be heated using a propane torch. These small ladel are often used by people pouring their babbit bearings or for example bullets for primitive type guns, muzzleloaders.
Once you get the knack of it you can advance towards a larger furnace, and eventually go to an electric furnace if desired. Electric offers the best way to melt metal cleanly with lowest loss of metal by forming dross, the skin or scum that's on the top of the molten bath.
The thing about Zinc that is different is that alloys like ZA-8, Z-12 or ZA-27 (the number indicates the percent aluminium in the alloy) will have melting ranges from about 710 to 910 degrees. In melting you should always use JUST ENOUGH superheat to get the casting poured. Extra superheating of molten metal is a big cause of metal related defects, like internal shrink, gas bubbles, etc. Also extra superheat will mean the metal shrinks a little more linearly so when you make a pattern you would possibly have to compensate more for patternmaker shrink.
One thing about this melting temperature, being this low, is that it is LOWER than the temperature at which molten metal begins to glow. This has a few effects. In brass, bronze, iron or steel melting which are at temps in the 2100 to 2800 range an experienced person can figure out the temp by the color. Before pyrometers that's how it was done for thousands of years. With metals that melt below the temperature where metal will incandece, you should rely on a thermocouple.
Depending on the metal type, eventually when you pass the melting point if you keep on heating up the metal it will eventually boil. For pure zinc that's about 1665 degrees F. But before you get to the boiling point a lot of zinc vapor will come off, this is not unlike the way water would evaporate more quickly at higher temps compared to lower temps even though you have not reached the boiling point 212.
Since zinc does not glow the impression can be that it is not hot and will not burn. This is not true please wear SAFETY GLASSES, gloves with cuffs tied off so metal cannot spill into the gloves, and cotton clothing (no polyester) and other precautions.
The other thing I would caution you is make sure your equipment is all dry. Anything wet with water or with free moisture will not only be a SAFETY HAZARD because the water will readily turn to steam, blowing motel metal everywhere, but the mooisture will cause defects in the castings. Even a drop of water can me a problem. It's okay if the sand in a green sand mold is slightly moist (i.e. "by feel") so long as the clay is absorbing all the excess moisture. If the inside of the mold has extra moisture the casting will have bubbles in the surface or a very rough appearance.
Somebody mentioned casting in graphite. I worked for a food equipment manufacturer, about 20 years ago, and we would cast small parts into graphite molds which are not only reuseable but produce excellent finishes and hold dimensions very well. I have also cast the ZA- alloys in sand and they produce a nice finish if the sand is well prepared. The castings can be easily buffed.
With any metal fumes, you should always use caution. In the case of Zinc this term used is "the zinc chills" or "the brass chills" (for brasses with high zinc content). The sysptoms are a feeling like the flu, etc. Definitelt don't overheat your zinc and don't stand around breathing any of the vapors. If you pour in an inside area make sure you have good ventilation. I have been working in foundries for 25+ years and I only know of 1 or 2 people who got "zinc chills".