Metal Casting Zone

How do i make the investment for lost wax casting?

I've asked this question and not gotten favorable responce. Plaster of paris, I guess will work for aluminum. You may beef it up with some silica sand. I've heard of dipping into drywall compound and coating with sand and/or paper, several coats. The burnout is the tricky part. You have to get all the wax burn out or it will spit hot metal all over the place.
I'm waiting on warm weather to try a couple reciepes. Winter is driving me crazy. Short trip.

I have just started playing with hydrolic cement as a investment. Works out well but sets up before i degass it, however it does cure fast and I can break it off the part easily.Honestly its alot better then the drywall joint compound something else im going to try is splitting the mold into 2 sections and reuseing it. This is for al so i hope the shrink factor is enough for the part to fall out. Ill post pics if it works out like Im hopeing.

ok some one some where has to know how to make thier own investment.
just renewing the thread trying to get some input....

have you pmed johncast?? find out what he uses. just a thought.

he was just on but i didn't PM, thought he might comment but has not thus far.

These guys may have some answers.
http://forums.reprap.org/read.php?70,21993

And let me know if you find something.

I've seen those guys before. Micro-glass spheres??? Hmmm. I want something cheap and easy to make. I've got some silica flour, fireclay, Plaster-o-paris(POP), and drywall compound. I'm hoping something with the drywall mud will work. I don't like the idea of the POP setting up before I'm ready.
I'm going to mix some silica flour and drywall mud, make it like a thin milkshake and dip some wax things in it, maybe crayons. In an artistic array of course. Then I'll heat it to melt out the wax and then fire it up to burn out whats left. I'll probably get some breakage but that's all part of experimentation. If I can't get something satifactory after a few tries, I'll probably order some Kerr Satin investment.$$$

Hi to all
Sorry to aonemarine that I didn't make a post here.Investment for casting in lost wax for jewellery is as far as I know a very special mix ,I can look up some books to find the exact properties that are in the investment. But I can't see why one would have to make ones own when it is freely availiable through any jewellery tool supplier.In small and large quanties 5KG Or 20KG. Any phone directory listing jewellery tools or similar products would I think stock this . I understand the mix of the investment powder is important,and has to be correct. If not powders can fall apart during pouring or crack in the burnout. KERR is the brand that my company has used for all the 28 years I was with them.To cast our men's rings in Gold and silver.I have used the same investment for my lost wax casting in brass of my model componets.And have had good results so far .(Apart from the fire scale on the castings ,I am yet to solve this problem) Kerr has expanded the range of investment mixes over the last 15 or more years. Platinum casting in the jewellery trade has increased ,and a special investment has been developed for this very high temp. casting.
Ps Thanks xlchainsaw for thinking of me to help aonemarine. johncast