making bronze

[GhostTownForge]

I know this is a smelting question, but I'm making a bronze plate and want to know the best percentage of copper to tin. This is my first time casting something, so I would appreciate any tips. 

[George N. M.]

There are lots of alloys of bronze for different puposes.  When you say "a plate" do you mean a serving/eating plate, an armor plate, a memorial plate with an inscription or what?

If this is your first time casting something I have to ask if you are set up to do this safely.  Handling molten metal is at least an order of magnitude more dangerous that forging hot, plastic metal.  Things can go wrong very quickly and the potential for life changing or ending injuries is very present.  Various folk here have plenty of tales of accidents with liquid metal and some of them will make your hair stand up.

Also, you are not "smelting" unless you are extracting metal from ore.

IIRC, the proportion of tin to copper is about 12% by weight.  But that may vary with intended use.

I suggest that you approach this project VERY cautiously and get some experience in handling lower melting metals, e.g. pewter, before starting to try to alloy copper and tin.  You need lots of preparation and PPE and a site where if things go wrong you won't burn down the family home.  Remember, you can buy bronze and forge it into what you want.  Also, if you possibly can find someone with experience or take a casting class at a local community college, vo tech school, etc. it will reduce the level of danger considerably.

IMO, jumping intro this without experience, guidance, or lots of learning is like trying to drive a Formula 1 race car in the Le Mans when you only have just gotten your Learner's Permit.  It's way beyond your level of competence.

Good luck but make informed, mature, and safe decisions.

"By hammer and hand all arts do stand."

[GhostTownForge]

Thanks! I want to make a bowl, but I thought it would be best to start with a plate poured into an open mold because I heard that thin sections could harden before fully being poured.

[George N. M.]

I suggest that you purchase a sheet of bronze and raise/sink it into a bowl.  The trick to working copper or bronze is to anneal often since it will work harden in the raising process.  I'd practice on a smaller scale to get a feel for the metal and the process.  I'd start with something fairly thick, maybe about 14 or 16 guage.

Annealling copper based metals is the opposite of doing so with ferric metals.  You get it hot and then quench it to soften it.

Starting with a sheet avoids all the problems and dangers of trying to cast something.  Also, I think you would end up having to cast a disk 1/4 to 3/8 stick and then having to beat it out into a sheet.  Your shoulders will thank you for not having to do that.

If you are not familiar with the raising or sinking process there are lots of references regarding the process for making armor for medieval re-enactments.  It is the same process used for making a helm.

"By hammer and hand all arts do stand."

[GhostTownForge]

Okay, thanks 

[anvil]

Also, look for silicon bronze. It is forgable hot or cold. Not all bronzes are forgable.

[Steve Sells]

I dont see where the smelting part is? just simple melting and casting

[GhostTownForge]

Sorry, that's a typo.  I meant to say casting.

I want to make my own bronze because I'm making a biblical replica for my pastor and want it to be as accurate as possible.

[George N. M.]

Yes, authenticiy is always good but in this case it is my opinion that creating and casting your own bronze would come at an unacceptable risk and expense given that you are a novice at casting.  And there is always the more authentic than thou aspect.  If you didn't source your copper from Cyprus or your tin from Spain, Central Asia, Cornwall, or Brittany you are making an authenticity compromise.  I am sure that your pastor will be sufficiently impressed that the bowl is bronze to care whether the source of the metal is a modern version or home made.  And besides, do you know what the accessory elements are in the copper or tin you would use?  Ancient alloys varied pretty widely depending on the various sources of metals.

Finally, I doubt your pastor would want you taking the unnecessary risks attached to the alloying and casting for just a bit more authenticity.  

Bragging rights are nice but what cost and risk is an acceptable price.

"By hammer and hand all arts do stand."

[GhostTownForge]

I'm going to do it, but I'd like to know how.

"There is a first time for everything."

[Irondragon Forge ClayWorks]

You might read the thread I just started.

[GhostTownForge]

But if I don't try, I'll never learn, correct? I don't want to sound disrespectful, but I'm trying to learn to cast, and it seems that nobody wants me to.

Thanks for the input, everybody. Sorry if I sound ungrateful, but I'm just trying to learn to cast.

[George N. M.]

OK, you are big boy and can make your own decisions about what is too dangerous or not and make your own benefit/drawbacks decisions.

What we are saying is that casting can be very dangerous and that a wise person would acquire some practice and knowledge before trying it.  We are pointing out that there is a lot of knowledge that you don't seem to have and it would be a good idea to adquire it before you start messing with very hot liquid metal.  This can be done with classes at community colleges or universities, books, videos, mentoring from someone more experienced, and practicing with small quanties of lower temperature melting metal.  If you want to skip all that, go ahead.  Just make an informed decision about how much you know, how much you don't know, and what risks are involved.

A few questions that you will need to answer for yourself:  What is my heat source and can it melt the amount of metal I want to use?, What kind of crucible to use?  What kind of flux am I going to use to prevent oxidation of the molten molten metal?  Do I have the correct tongs to hold the crucible?  Do I have ALL the necessary PPE?  What kind of mold am I going to use and does it need to be preheated?  Do I need to practice all the motions of making the pour with a cold liquid?  Where am I going to souce copper and tin and how much do I need?

There are any number of foundry shop textbooks out there.  I suggest that you get a good one and read it before trying it hot on your own.

We are not trying to be wet blankets just to discourage you.  Many of us have been around many years and have seen and heard of folk being seriously injured or killed by getting in over their heads and we do not want that to happen to you.  We are not your parents and cannot forbid you doing what you want but make sure you are making informed decisions.  We have seen enthusiastic people charge ahead and we have done similar things ourselves, sometime successfully and sometimes not.  But we do have a better idea where the booby traps and mines are because we have crossed that field ourselves.

If you are not a member already I suggest you join the New Mexico Blacksmiths Association and enquire if anyone there has foundry expertise and if they would be willing to teach you.

Good luck and let us know how it all turns out.  We would love to see photos of the process and the result.

[Glenn]

I got out of casting when recycled materials were melted and a pot full of liquid metal developed a problem. PLAN B had to immediately implemented.  Had I not used the wisdom of others, it could have easily been damage to property, and or a trip to the hospital.   Fortunately everything worked out but it was enough to scare me away from casting. 

If you still insist on casting, even on a small scale, study everything you can find on the subject. Seek out those that know what they are doing  Learn what to do, what not to do, the proper and safe way to do it.  Youtube is not your friend here, and after one short class is not the time to adventure out on your own.  Proper protective gear and proper tooling can be expensive, but much less expensive than a hospital visit.  Things will go wrong, it is just a matter of when.

[Purple Bullet]

One more word of caution: DO NOT set up for casting on a concrete floor. When molten metal lands on concrete it causes the moisture in the concrete to turn to steam and the result is concrete shrapnel WITH drops of molten metal erupting from the floor! 

[JHCC]

10 hours ago, GhostTownForge said:

But if I don't try, I'll never learn, correct? I don't want to sound disrespectful, but I'm trying to learn to cast, and it seems that nobody wants me to.

Thanks for the input, everybody. Sorry if I sound ungrateful, but I'm just trying to learn to cast.

Don't get us wrong; we very much want you to cast. Indeed, we want you to develop your skills and artistry as much as possible. However, we want even more for you to do this SAFELY. Casting is an inherently dangerous process and not something you can easily or safely pick up on your own. Hence the recommendation to take a class.

Additionally, one of the things we talk about a lot here on IFI is how to make good decisions about process and goals. None of us is a wealthy dilettante with unlimited time and resources, so learning how best to approach a problem given a particular set of circumstances is an extremely valuable skill. This means asking first "What is my goal?" and second "How can I best achieve that goal?"

In your case, you've talked about making a bronze bowl for your pastor. Is the goal the bowl itself? Or is the goal to learn casting, with the bowl being a means to that end? If the most important thing is making a bowl, then learning how to raise one from flat sheet (be it copper, bronze, or brass) is going to be faster, easier to learn, cheaper, and safer. If the goal is to learn casting, that's going to require a significant investment in material, tools, safety equipment, education, and time before you get anywhere near being ready to make a bowl. Either is a legitimate option, but you need to be clear about your own motivations and desires as well as what the implications of each choice will be before you move forward. Either way, we are here to help.

(My personal recommendation would be to learn to raise a bowl from flat sheet. I've been working on forging bowls hot from sheet steel, and it is a fascinating process. As noted above, bronze can be worked cold, so long as you anneal it regularly, which can be done with something as simple as a plumber's propane torch.)

[anvil]

You might be at the wrong site, well, not wrong site, but This is a blacksmithing site. We forge iron and stuff like that. We may have a bit of knowledge and advice for you, but you will prolly get better info for your project if you go to a casting site, and most likely there is a bronze casting site if you look. 

[ThomasPowers]

Have you explored Backyardmetalcasting.com  (now alloyavenue.com IIRC) a wide range of alloys were used in Biblical times often depending on what the intended use was; (mirrors use different alloys than swords for instance.)  a 90% copper 10% tin was a common alloy---I get my tin from rotometals.com)

May I respectfully point out that due to liability laws in the USA; you are basically asking us to risk our house, car, shop, savings on whether you can follow directions correctly and will take the proper safety precautions.  Unfortunately I'm not willing to make that bet based on what I have read.

I learned taking an out of hours metal casting class from a local university's art department and have been using my forge to cast silver, copper, brass, bronze since the early 1980's.  (Mainly blade fittings...)

[Irondragon Forge ClayWorks]

One thing to remember is our answers go out to the person asking the question, along with everyone reading the forum/thread. Currently there are 15 members and 166 guests on the forum. If our answers influence any of them, it may prevent a disaster or lead those interested in a topic to seek out more knowledge on the subject.

As a teenager I worked in a business that made a lot of those cast aluminum custom license plate's and frames. My job mainly was to pack the mold with green casting sand and a sample of what was to be cast, so the foundry operator (boss) could pour the molten metal into it. In the year and a half I worked there, I learned a lot and even got a chance to pour the metal occasionally. I can tell you metal casting is not for the faint of heart.

[GhostTownForge]

Thanks for the input, everybody! I am sorry if I sound ungrateful. I really appreciate the support.

[Terry Griner]

I read through this thread before I commented to be sure I wouldn't be duplicating what others said. 

Safety should be your first concern, and all the warnings above are correct. But I assume you are over 18 and therefore an "adult".

I have been casting Brass/Bronze, Aluminium and Pewter off and on since 1979.

So you want to create a food safe object? You want to be sure to get 99% fine copper and tin. Buy from someone like Rio Grande or another reputable supplier, not the local scrap yard. Some of the stuff out there has lead in it, and lead and food don't mix! Your mix should be 95/5 copper to tin. That will give you the best flow.

Now the questions...

1> Are you sure you want to cast this? Hammering was done much more often in Biblical times.

2> What are you going to cast into, Green sand, oil sand, Plaster mold? Don't have an answer, research the materials.

3> What are you going to use for a Crucible? Don't use Iron, Copper will "eat" it and you could get a hole!

4> What is your heat source?

     4a> Do you have a Gas forge?

      4b> Or a Coal/Charcoal setup?

Earlier Thomas mentioned looking up AlloyAvenue.com I recommend this as well. Also go to your local library and see what they have in the Technology section. there are some great books for small home foundries, also look on line there is lots of information out there. But with the internet get at least 3 sources that agree before you try something. 

Best of luck!

Terry Griner

Head Imp

Dancing Rabbit Foundry

Columbus Ohio

[GhostTownForge]

im happy that you think im 18 but i am 14

[George N. M.]

OK, this explains a lot.  I don't want this to sound like I am slamming you or adolescents in general but this is part of why you want to go ahead with making your own bronze alloy rather than buying bronze sheet to make the bowl for your pastor.  It is common, and we know because we were all once your age, that it is really easy to get tunnel vison on a particular goal and minimize the difficulty and risks of getting to that goal.  One thing that is learned with years of life is that the journey to the goal is sometimes pretty tough.  We have learned where the landmines are by stepping on them.  So, you are getting the benefit of our mistakes and injuries without having to go through the pain and frustration that we have.

Also, your parent(s) or guardian HAVE to be part of this process and decide what is safe and feasible or not.  Trying to do this without having them as part of the decision making process is looking for trouble, tears, and discipline that you won't like.  The upside is that you may recruit them into the process and make this a family project which would have more benefits than if it is just you.

Again, good luck and we would love to see pictures of the process and the final product.

"By hammer and hand all arts do stand."

[Steve Sells]

and since I doubt your research has covered it already, I have to state that PPE is not cheap.  Where are you getting the protective equipment? and dont you dare to think you dont need any

[GhostTownForge]

I do have safety equipment, but I was wondering if I should wear gloves because I have heard that leather gloves can shrink onto your hands