Help with bronze casting

Casting

Hello everyone. A few years ago I built a small furnace and played with the metal casting process. I tried both aluminum and bronze. I have not work with any of it in a while. I now have some peaces that I have sculpted and want to make some bronze casting. There is so much information out about the process its easy to get confused. I will be making rubber molds of my work and casting wax into them. I will then attach the proper runner bars, gating, and pouring sprue.

I have worked in a cast iron foundry for about 15 years now. I have built most of my equipment and work with a lot of knowledgeable people in the sand casting process.
Unfortunately, none of them are very experienced with the materials and process for investment casting.

Im only interested in casting bronze at this point. I know that I will have to continue experimenting to find the process that works best for me. However I would like some advise about some of the specifics, mainly what material to use as an investment, and there cure and burn out times.

I put a lot of hours in at work so its will be hard for me to do burnouts that last for multiple days. I would appreciate any advice. Also, so any of you know of any good books on the bronze casting process?

Thanks
Ksquare


visitor's picture

Ksquare, Plaster investment

Ksquare,

Plaster investment casting does take a bit of time to burn out the investment but the materials and process are "relatively" simple and straight forward. Ceramic shell casting is a bit more technical, there is more equipment, shell materials are more difficult to get in smaller quantities, etc. BUT the burnout is in minutes, the detail is fingerprint accurate. So first I think you have to decide whether it is going to be shell or investment. If you have any questions about shell casting, you are welcome to call or write me. Investment casting of bronzes is a Bruce Paul Fink specialty so if you go that route, you might give Bruce a call or r mail. Once you decide the method, then either of us can help you with the process but to go over it here is WAY TOO much info.

John


ksquare's picture

Thanks John

Thanks for the input and offer John. I may drop one of you a line in a few days. I work in a foundry for a living and I know a few of the suppliers reps. I think that I will be able to get the material needed. The problem is I’m not sure what products are the best. Most of them have told me they can get what I need; they just need to know what I need.

I would not be opposed to using plaster and sand as an investment. I like the ideal of not having to do all of the steps in the investment. One of the problems is I don’t have a supply of natural gas. I have to do my burnouts with waist oil or propane and lengthy burnouts can get expensive.. Again all of my equipment is homemade and works well; however I can’t leave it unattended. Maybe I should look into building an electric burnout oven or kiln??

I’m sure if I knew the product and procedure I could build the equipment needed to do the job. Most of the castings I intend on doing are smaller in size. I like to sculpt and carve and want to do the castings to give away to family and friends. If I got good enough in both the sculpting and casting process I may even try to sell a few. That’s a long way down the road and much to learn between now and then. Its just a hobby at this point.

Thanks
Kenny


visitor's picture

Casting

Hi Ksquare I do scrap metal sculpture but have gotten very interested in casting but know nothing about it. I have sought local help but no one has stepped up to the plate. Can you give just a basic outline of what you want to accomplish with casting or recommend a book that a novice can follow. I think I can melt any of the white metals silver, brass, pewter and some unknowns as I have an excess of candle holders. I built a melting pot I can put in my Po Boy forge...It gets things very hot but I have to finish it off with Oxi/Ace, What do I need for making molds? I melted down a role of pennies but had nothing to pour it in. Any info would let me know if I can do this or stop fooling myself. I did teach myselt how to mig weld, braize and cut with Oxi/Ace. I never took shop as I was to busy with football wrestling and of cource the babes!
Thanks,
gimperfi


ksquare's picture

Hello Gimperfi, to be honest

Hello Gimperfi, to be honest with you I don’t know that I have the experience needed to be of much help. Im also in the learning process. I have seen several books suggested here in the forums. There is a lot of info on the net about building furnaces ect. You really must first decide what typs of metal you intend to melt. What types of casting you want to do? If you could get by with sand casting that is the cheapest and easiest way to go. I have a feeling you want to do art work. In my limited experience sand casting will not be a good option.

I will tell you that there is a lot of good info on this site in the past post. Please just be careful. I have read some of the others caution people about working with molting metal and I have to repeat it. It is very dangerous. I have seen some bad burns. One thing to note, burns from molting metal are always serious. If you spill it on your foot are leg you are very likely to loose it. Burns of that nature will put you into shock very fast and if you don’t have someone with you that knows what to do you could very well die from it.

Im not trying to talk you out of it rather warn you of the risk. If you decide to proceed get the proper protective equipment. Also do not melt scrap metal. I can tell you that two are three days in bed with metal fume fever are not pleasant. There is no way to know what you are getting when buying scrap. I have lots of hobbies and I will tell you, I am embarrassed to admit. Out of all of my hobbies I have wound up in the emergency room twice doing casting at home.

I hope I helped.
Kenny


ksquare's picture

Sorry

Gimperfi, I have to apologize. After reading my reply to you I think I may have got both of us confused. I hate to write and type so sometimes I have a hard time conveying what I’m trying to say in writing.

When I mentioned the process of sand casting I was referring to green sand (its really black) and resin sand. Green sand casting is probably the cheapest method of casting. Its basically sand mixed with the proper binders. The down fall of it is that it has to be mulled. Simply mixing it will not do. If you have a foundry near by I’m sure you could get a few buckets of it for little to nothing. Green sand is normally reused many time and remulled after each use. A quality foundry is always monitoring the sand quality. And like wise turning out some of the old and adding new sand. This is only done a little at a time. The old sand that is turned out has to be disposed of. That would be what you ask for.

Resin sand is just that. It’s a sand of certain properties and size that is mixed with resins. It’s a little more expensive but a lot easier to blend for the hobbyist. I’m not sure I would try reusing it at home however. If you are not able to test the sand you will build up excess resin. That will cause gassing issues. I will tell you that resin sand stinks very bad and puts out a lot more fumes.

Both of these are great for doing peaces that are not too intricate like plaques and such. When making patterns for sand casting you have to make sure and have a draft (angle) so the finished mold will draw off the pattern. To get complex shapes requires many cores and leaves a lot of parting lines that have to be cleaned up.

If it is sculptures that you want to do then you are stuck where I’m at lol. I’m trying to learn the whole investment / shell process as well.

As far as furnaces go I will tell you what I have built. I got about 5 bags of refractory and lined a barrel the was cut off about half way. I used a cardboard tube that measures about 10 to 12 inch in diameter. I ran a two inch pvc pipe in it for the burner hole. I blocked and screwed everything down and poured in the refractory. I let it set a couple of days and pulled out the forms. I then let it cure a few more days. After that I built a charcoal fire in it and let it burn down. I did that a few times then a day or so later I did the same thing but feed air into it to get it really hot. If you would like I can send you the drawings and material list.

I hope I help that time
Ksquare


johndach's picture

gimperfi and Ksquare and

gimperfi and Ksquare and all,

Sorry that I was not logged in for the first reply. I am a shell caster but we do some jewelry work in investment (Cynthia was a high end jeweler for 30+ years before we got togethar and started doing bronzes). I would be happy to help either of you with any questions, how to's etc. Feel free to e mail me or call (I can call you back as we have "free" long distance for a monthly charge). I have got to remember to log in when I reply on this list.........

John Dach
360.681.4240
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com


timcos's picture

All of our projects lend

All of our projects lend themselves to ceramic shell casting. We have gotten pretty good at it.

We are a small artisan foundry only working on 4 or 5 projects at a time...and of course some of these projects are broken up into as many as 18 smaller panels. Any larger and the shell has a tendency to blow out from the weight of the bronze.

Detail is fantastic.

Tim Costello
Zingology Manufacturing
Fine Art Bronze Foundry
www.zingologymfg.com


lsw's picture

I use equal parts water,

I use equal parts water, silica sand, silica flour, and casting plaster.  I could give you the wgths on those if you want.