An important, even essential tool in ceramic labs, studios and classrooms for mixing test and production slurries (body and glaze) is a good propeller mixer. Particles in ceramic powders can be exceptionally small (and often agglomerated) and wetting all their surfaces requires the injection of energy into a slurry that only a device such as this can do. This is especially important when the slurry is deflocculated and thus has a low water content. In addition, slurries get lumpy during use, a good mixer is needed to smooth them back out.
Home-made propeller mixer with mount and switch
This is a heavy-duty unit, home made, with a 1/3 hp motor. It that can handle 5 gallons of high density suspension glaze or body slurry.
Get a variable speed lab mixer at Amazon.com
You need variable speed (not constant speed). Many of these have timers also. The prices range from $100 to thousands of dollars. Spend a little more and you will not regret it. A table-top device would normally be rated at 10L or 20L capacity. However, it is obviously easier to stir a thin liquid than a thick ceramic slurry so get a machine with plenty of capacity. If they label it a "lab mixer" then it is not too large to fit on a table top, a 20L capacity should assure that it will handle any glaze or clay slurry bucket that you would mix with it (e.g. 1-2 gallons). It should be capable of at least 1500 RPM. If the shipping weight of the package is 15-20 lbs (7-9 kg) it should be about the right size. They do not always come with the shaft and propeller, watch for that.
A must-have: Laboratory variable speed propeller mixer
If you are at all serious about testing glazes and clay bodies, you need one of these. There are other methods, but nothing else comes close to this. It is the most valuable and frequently used tool in any ceramic bodies and glazes testing lab or classroom. These are expensive new, this Lightnin 1/20 hp variable speed cost more than $1000 many years ago, now it could be $4000! But you can get them used on ebay.com. I adapted a mount (to give it vertical adjustment) from a hardware store. Propellers are also expensive, but you can design and 3D print them yourself or have them printed at a place like shapeways.com.
Optimimal casting slurry properties impossible without good mixingShow on Post Page
A video of the kind of agitation you need from a power mixer to get the best deflocculated slurry properties. This is Plainsman Polar Ice mixing in a 5 gallon pail using my mixer. Although it has a specific gravity of 1.76, it is very fluid and yet casts really well. These properties are a product of, not just the recipe, but the mixer and its ability to put energy into the slurry.
Printing a prototype propeller for my Lightnin lab mixer
An example of how handy the ability to print in 3D can be. The worn-out stainless propeller costs $300 to replace. But the size and pitch of the blades is not ideal for the work I do. I print them in PLA plastic, this enables experimenting with different sizes and pitches. When one works well then I can have a stainless one printed at shapeways.com. These plastic propellers are surprisingly durable and it was easy to print one the with a hole the exact size needed, it fits tight on the shaft and never moves.
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