Metal Casting Zone

Thanks Johncast,
I had only seen Kerr available in large quantities, I hadn't thought of jewelry supply stores. I know of one in Columbus, Ohio. I had bought some engraving tools there before.
Do you know what the shelf life is?
I'll check them out.

The main reason for wanting to my my own investment is due the cost of shipping, there are no local suppliers in my area. For 50 lbs of investment the cost is 35.00 for shipping 30.00 If I ever wanted to produce parts and be competitive this cost need to be lower. I checked out the site you linked, I have tried all thier suggestions previously but have not come up with a true investment that will degass properly.
someone told me to use powered pumice stone, havnt tried that yet but will as soon as I can find some.

Ok I found the kerr investment in 4.4 lb qty, still costing 26.00 to my door but I want to see how real investment acts. Thanks johncast

There's a 33# cube on e-bay for $76 with free shipping. It was Kingsupply or something like that.

Hi everybody!

This my first post here. Actually, I've registered myself just to answer this topic.

I would like to share with you my experience with cheap, "third world" investment:

What I do is a mixture of Plaster of Paris and ground clay. By "ground clay" I mean the red stuff that is used for tennis courts. Ground clay is produced by grinding broken tiles and bricks into a very fine powder. Go to a tennis court, ask for a bag of that stuff or ask for the name of their supplier. Don't try to grind the bricks and tiles yourself. Simply doesn't worth it.

I mix 2 (two) parts of ground clay and 1 (one) part of plaster of paris. Mix them thoroughly, getting some kind of pink powder. Add water. Think of ground clay as tiny bricks, soaking the water, so add a lot of water. You want the consistency of latex paint.

Pour the investment. If the wax is big enough or has a very detailed surface you can brush the first coat of investment. Remember, however, that this investment is quite fragile.

Once done, I strongly suggest to wrap the investment in chicken wire and apply another coat of investment, this time a thick one.

This investment works beautifuly with aluminum and bronze. Copies every single detail, even fingerprints.

The ONLY problem is the amount of water needed to pour the investment. You need to get rid of ALL that water before attempting any molten metal pour. Otherwise, water will turn into steam and will crack the mold or, even worse, explode.

I create a custom made kiln for taking away all that water and dewaxing the mold in the process. Using masonry bricks I build the kiln around the mold, no cement or whatsoever. With an old boiler burner and a piece of sheetmetal that acts as fire diffusor I dry the mold overnight. Your aim is to get the mold almost white (fairly pink actually) and with no black residues (wax) around the feed gate. If you take a peek during the night you can see the mold actually glowing...

If you've got another source of energy for your furnace (I mean, if you can dry the mold and melt the bronze at the same time) pouring the metal while the mold is still glowing will help both preventing a temperature shock of the mold and increasing the ability of running and getting into complex places of the molten metal.

My two cents.

Thanks for the input mdurruty, and welcome to the forum!
I also found a recipe for an investment useing POP its 50-50 pop and silica flour with 1-2% wood flour for burn out. havent tried it yet due to the savings over buying the commercial stuff isnt that great to worry about it just yet.

I took a sculpture class in college and we used plaster for lost wax bronze casting. I am not sure what you mean by DIY exactly. I have since found burnout to be a bit tricky and at times I break the plaster with the heat.

I have had bad luck fairly consistently with drywall joint compound.

Hi to all

Disscussing Investment again I see, Sorry I haven't been in to this site until now . I am waiting for the last 4 hours of a burn out to do some lost wax brass cast to day . So while I wait I check out the forum.. My new controller is maintaining furnace at 730oc spot on. When I perfect my ability to send photos to this site I will endevour to send some so you can see what I do.

Investment used by john cast is Kerr Satin cast 20 . One type of investment of several that Kerr make for varing requirements. A new one now for platinum casting.

Just mixed some last night and think the water I used was a little to warm at 23oc as the investment was just on the turn to set at 8.5 minutes as I finished filling the flask. Usually don't have that happen.
I gess you could make your own but would need a lot of trial and error to perfect. Why not buy the available investment. this material has a vital roll to play in the lost wax casting process . It has to be a correct mix to work properly.

Ps Did a sand casting of some alluminium last month a special ring sprue former required for my spin casting. turned out well ...What temp is best for aluminium die cast off old car parts. I was on 840oc I think.

I gather that the ancients used water based clay made into a slurry and then sprinkled sand over it. Repeated this sequence a few times to get a thick enough coating. Seems the same can be done now. Just a thought, the 1st slurry layer should probably be followed by a second before sprinkling any sand into the moist clay.

Wikipedea notes that in the 1800's the use of plaster slurry followed by a sprinkling of used hardened plaster was going on. That seems very practical and accessable. Have yet to try any of this myself.