Ok here's a nerd question does the bellows need to be a minimum away from the fire it looks like you run the danger of sucking the fire up the pipes and either burning the bags or the assitants hands
@Sleepindragon2 The continuous flow of air from the two bags stops this danger. The air enters the openings at top of the bag and is forced out the nozzle at the front. The alternating action of the bellows keeps up the continuous flow of air. The biggest danger is sparks which do indeed burn the bag or hands! Sometimes it is necessary to set up a protective fence between the "bellows slave" and the fire, but as it is often a one person operation this is not always possible.
Great video to watch,I've just started a course in Archaeology in IT Sligo. Have to do a log book every week and my first artefact is a bronze age axe head mold.
@whowantsabighug That is a handmade crucible. It is a mixture of high firing (grey) clay & sand. It may also contain fine "grog" (crushed fired clay or crushed crucibles) and a very small amount of vinegar to add flexibility to the mix. These crucibles can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
Also, did you fire the crucible before the pour, or just use a slow heat to dry it before adding the bronze? With aluminum, mostly any carbonaceaous matter will help to prevent oxidation, like charcoal or cardboard dropped directly into the melt, simply to reduce the atmosphere of free oxygen.
@demac777 Generally once the new crucible is dry, it is ready to go into the fire. If it is ready to be fired, it might as well have metal in it and be used for a pour! The original heat is "slow", but by pottery standards it is heated very quickly and with little regard for a controlled temperature gradient. Yes the charcoal fire consumes most of the oxygen, and bits of charcoal floating on the molten bronze keep it very clean.
Did you use the lost wax method to form the axe head itself and then wrap the fireclay around it for the investment? I have done some large scale pours using silicon carbide crucibles and plaster investments, but I would love to try something more primitive like this. We always used crushed glass to cap the bronze and skim before the pour.
@demac777 The process of melting the wax out of the mould is the "lost wax" part. The wax axe head is formed from a carved mould or directly by hand, then a mix of clay, sand, ashes and horse dung (not fire clay) is used to make the mould around the wax. Yes we also use crushed glass, mainly for large pours. Small pours tend to be very clean - the charcoal fire helps keep the metal very clean.
@retepvosnul Generally we use charcoal or dry sticks as an anti-oxidant. By stirring the molten metal with bone dry willow sticks, it will burn off absorbed oxygen. The charcoal fire itself consumes most oxygen near the metal, and inevitably charcoal will fall into the crucible and float on the surface of the metal. It is all good! Just skim it off before casting, and holding slag back with a stick while pouring continues this process to the last moment.
@umhaaois Thanks for the answer ! That is very useful information. So you use only those items and no modern flux agent like borax, which I understand is a very efficient flux. Have you heard of, or know, what the effect of more common salts would be in molten Bronze, copper or tin ?
@retepvosnul We use borax if we need to "cast on" molten metal with already solidified metal. It can be used in sealing the surface of crucibles, a light slip of borax is painted onto the cold crucible. Borax can be used as a "cover flux" on top of the molten metal, but so can charcoal or crushed glass. Use of salts at these temps will create hydrogen chloride gas and chlorine vapors! Hydrogen chloride gas is highly toxic, also hydrogen chloride and water vapor form hydrochloric acid! Bad.
@umhaaois Salt however is used in aluminium melting. Does it react differently or does the temperature difference result is less gasses being produces ?
@retepvosnul Sorry, I haven't done any aluminium casting, I see now what you mean. My experience of salt in hot environments is salt glazing in ceramics, which uses a damp salt (sodium chloride). The sodium forms the glaze and the chloride bonds with the water vapour to create hydrogen chloride gas. From what little I have read, the use of salts in the form of a molten cap or bath is still a highly dangerous and toxic process. I would like to hear any info you have on salt in aluminium casting.
@wildlifelessons That is a handmade crucible. It is a mixture of high firing (grey) clay & sand. It may also contain fine "grog" (crushed fired clay or crushed crucibles) and a very small amount of vinegar to add flexibility to the mix. These can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
Great video!! jlasud: water quenching does in fact effect the hardness of cooper alloys. When quickly quenched in water, a martensitic structure is formed, increasing hardness. When air cooled, a martensitic structure is not formed, making it very ductile and tough. Cold work can then be used to harden the material from there (hitting with hammer) but the crystaline structure is in essence smashed and flattened, which can be avoided if heated and annealed. So, putting in water is important.
@Qtturner1 Thanks for that reply, especially the term"martensitic structure" - very helpful! Copper alloys are tricky, I refer you to keytometals com Article71 "Quench-hardening alloys comprise aluminum bronzes, nickel-aluminum bronzes, and a few copper-zinc alloys. " As we are using a Bronze Age, pure copper-tin bronze, it is not necessarily true that quenching will harden this alloy. I have found that this alloy tends to heat soften and cold work harden.
@ohvnaq Depending on the volume, it can take 20 minutes for o.5 kilo or at least an hour for 2 kilos. When melting copper we add the tin at the last moment, as its melting point is so low it would burn off long before all the copper melts. When we are re-melting bronze, it goes much faster.
Cooling the casting with water does affect the properties of bronze compared to slow air cooling? Is the crucible homemade?If so what kind of clay\sand ratio does it have.I've read that readily bought fireclay works well too.
@jlasud - Quenching it in water helps to shatter the mould. It has no effect on the hardness, as bronze is work hardened, so is in an annealed state after casting regardless of cooling speed. Letting it cool slowly prevents the risk of accidental damage, as bronze is fragile while hot. It is a handmade crucible, from high firing clay with a very high sand ratio (30 to 50%), it may also contain fine grog. I do not see why fireclay would not work., but I have not tried it.
@umhaaois I made a few days ago a crucible with about 25%sand and red clay dug out from a hillside.I want to make a similar setup for casting bronze fokos head ,dagger and arrowheads.I'm new to casting and doing my homework...could use some advices and infos.Thanks for sharing , best wishes!
@jlasud Google turned up this "A red earthenware contains a large amount of iron which acts as a flux. An earthenware clay body can fire to maturity at about 1830⁰F (1000⁰C) and can melt at 2280⁰F (1250⁰C)." These temperatures are very close to the ones necessary for good flowing bronze. A red clay crucible may not survive, but it is still worth trying out to see what happens!
@Youcantbeseriousa123 - we have not yet had the opportunity to use mined ores. which would be nice! The copper is generally electrical copper wire from recycling (almost 100% pure copper) and the tin is bought in ingot form. By weight we generally use roughly 90% copper to 10% tin.
@Henrik4950 - That is a handmade crucible. It is a mixture of high firing clay & sand. It may also contain fine "grog" and a very small amount of vinegar to add flexibility to the mix. These can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
Wow that's really cool, so all it takes is essentially bags and air to melt bronze? That's awesome. This is a very interesting experiment you folks have going on.
Ok here's a nerd question does the bellows need to be a minimum away from the fire it looks like you run the danger of sucking the fire up the pipes and either burning the bags or the assitants hands
Sleepindragon2 2 months ago
@Sleepindragon2 The continuous flow of air from the two bags stops this danger. The air enters the openings at top of the bag and is forced out the nozzle at the front. The alternating action of the bellows keeps up the continuous flow of air. The biggest danger is sparks which do indeed burn the bag or hands! Sometimes it is necessary to set up a protective fence between the "bellows slave" and the fire, but as it is often a one person operation this is not always possible.
umhaaois 1 month ago 2
@Sleepindragon2 your stupid
MrBrandon024 2 weeks ago
love it
cvbpo 3 months ago
so it is hard to make a 53cm long bronze mask??press link to see..badran 106..
they told me it is ancient...
badran106 4 months ago
Great video to watch,I've just started a course in Archaeology in IT Sligo. Have to do a log book every week and my first artefact is a bronze age axe head mold.
I can't figure it out :P
DirtxInxThexGround 5 months ago
@DirtxInxThexGround Stick with it. Do you have to recreate the mold, or investigate an existing shard?
umhaaois 5 months ago
Oh matey, how do bronze tools keep the sharpess? Like the bronze axe which you made?
emel60 6 months ago
thank god for gas
therichm10 7 months ago
Are you interested in accumulating large amounts of pre-1982 copper cents? I have the ability to produce 1 to 2 tons a month. Let me know.
humanitarianguyana 7 months ago
What is the crucible made from?
whowantsabighug 8 months ago
@whowantsabighug That is a handmade crucible. It is a mixture of high firing (grey) clay & sand. It may also contain fine "grog" (crushed fired clay or crushed crucibles) and a very small amount of vinegar to add flexibility to the mix. These crucibles can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
umhaaois 8 months ago 2
The guy pumping the billows must get a good workout.
disturbedone5009 11 months ago
Ha
Is this Robert live in Balinaclash???
lyi6026 1 year ago
the old style woooooooooow is really nice
swordsman3333333 1 year ago
Also, did you fire the crucible before the pour, or just use a slow heat to dry it before adding the bronze? With aluminum, mostly any carbonaceaous matter will help to prevent oxidation, like charcoal or cardboard dropped directly into the melt, simply to reduce the atmosphere of free oxygen.
demac777 1 year ago
@demac777 Generally once the new crucible is dry, it is ready to go into the fire. If it is ready to be fired, it might as well have metal in it and be used for a pour! The original heat is "slow", but by pottery standards it is heated very quickly and with little regard for a controlled temperature gradient. Yes the charcoal fire consumes most of the oxygen, and bits of charcoal floating on the molten bronze keep it very clean.
umhaaois 1 year ago
Did you use the lost wax method to form the axe head itself and then wrap the fireclay around it for the investment? I have done some large scale pours using silicon carbide crucibles and plaster investments, but I would love to try something more primitive like this. We always used crushed glass to cap the bronze and skim before the pour.
demac777 1 year ago
@demac777 The process of melting the wax out of the mould is the "lost wax" part. The wax axe head is formed from a carved mould or directly by hand, then a mix of clay, sand, ashes and horse dung (not fire clay) is used to make the mould around the wax. Yes we also use crushed glass, mainly for large pours. Small pours tend to be very clean - the charcoal fire helps keep the metal very clean.
umhaaois 1 year ago
Do you use any sort of flux for purifying or pouring ?
retepvosnul 1 year ago
@retepvosnul Generally we use charcoal or dry sticks as an anti-oxidant. By stirring the molten metal with bone dry willow sticks, it will burn off absorbed oxygen. The charcoal fire itself consumes most oxygen near the metal, and inevitably charcoal will fall into the crucible and float on the surface of the metal. It is all good! Just skim it off before casting, and holding slag back with a stick while pouring continues this process to the last moment.
umhaaois 1 year ago
@umhaaois Thanks for the answer ! That is very useful information. So you use only those items and no modern flux agent like borax, which I understand is a very efficient flux. Have you heard of, or know, what the effect of more common salts would be in molten Bronze, copper or tin ?
retepvosnul 1 year ago
@retepvosnul We use borax if we need to "cast on" molten metal with already solidified metal. It can be used in sealing the surface of crucibles, a light slip of borax is painted onto the cold crucible. Borax can be used as a "cover flux" on top of the molten metal, but so can charcoal or crushed glass. Use of salts at these temps will create hydrogen chloride gas and chlorine vapors! Hydrogen chloride gas is highly toxic, also hydrogen chloride and water vapor form hydrochloric acid! Bad.
umhaaois 1 year ago
@umhaaois Salt however is used in aluminium melting. Does it react differently or does the temperature difference result is less gasses being produces ?
retepvosnul 1 year ago
@retepvosnul Sorry, I haven't done any aluminium casting, I see now what you mean. My experience of salt in hot environments is salt glazing in ceramics, which uses a damp salt (sodium chloride). The sodium forms the glaze and the chloride bonds with the water vapour to create hydrogen chloride gas. From what little I have read, the use of salts in the form of a molten cap or bath is still a highly dangerous and toxic process. I would like to hear any info you have on salt in aluminium casting.
umhaaois 1 year ago
@umhaaois I understand, Thanks. If I find anything in research I'll give you a PM if I think I found something that might be of interest to you.
retepvosnul 1 year ago
what did you make the container that held the molten bronze in out of.
wildlifelessons 1 year ago
@wildlifelessons That is a handmade crucible. It is a mixture of high firing (grey) clay & sand. It may also contain fine "grog" (crushed fired clay or crushed crucibles) and a very small amount of vinegar to add flexibility to the mix. These can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
umhaaois 1 year ago
Great video!! jlasud: water quenching does in fact effect the hardness of cooper alloys. When quickly quenched in water, a martensitic structure is formed, increasing hardness. When air cooled, a martensitic structure is not formed, making it very ductile and tough. Cold work can then be used to harden the material from there (hitting with hammer) but the crystaline structure is in essence smashed and flattened, which can be avoided if heated and annealed. So, putting in water is important.
Qtturner1 1 year ago
@Qtturner1 Thanks for that reply, especially the term"martensitic structure" - very helpful! Copper alloys are tricky, I refer you to keytometals com Article71 "Quench-hardening alloys comprise aluminum bronzes, nickel-aluminum bronzes, and a few copper-zinc alloys. " As we are using a Bronze Age, pure copper-tin bronze, it is not necessarily true that quenching will harden this alloy. I have found that this alloy tends to heat soften and cold work harden.
umhaaois 1 year ago
awesome! how long did you have to fire the materials before they melted? did you put pieces of copper and tin together in the melting pot?
ohvnaq 1 year ago
@ohvnaq Depending on the volume, it can take 20 minutes for o.5 kilo or at least an hour for 2 kilos. When melting copper we add the tin at the last moment, as its melting point is so low it would burn off long before all the copper melts. When we are re-melting bronze, it goes much faster.
umhaaois 1 year ago
Cooling the casting with water does affect the properties of bronze compared to slow air cooling? Is the crucible homemade?If so what kind of clay\sand ratio does it have.I've read that readily bought fireclay works well too.
jlasud 1 year ago
@jlasud - Quenching it in water helps to shatter the mould. It has no effect on the hardness, as bronze is work hardened, so is in an annealed state after casting regardless of cooling speed. Letting it cool slowly prevents the risk of accidental damage, as bronze is fragile while hot. It is a handmade crucible, from high firing clay with a very high sand ratio (30 to 50%), it may also contain fine grog. I do not see why fireclay would not work., but I have not tried it.
umhaaois 1 year ago
@umhaaois I made a few days ago a crucible with about 25%sand and red clay dug out from a hillside.I want to make a similar setup for casting bronze fokos head ,dagger and arrowheads.I'm new to casting and doing my homework...could use some advices and infos.Thanks for sharing , best wishes!
jlasud 1 year ago
@jlasud Google turned up this "A red earthenware contains a large amount of iron which acts as a flux. An earthenware clay body can fire to maturity at about 1830⁰F (1000⁰C) and can melt at 2280⁰F (1250⁰C)." These temperatures are very close to the ones necessary for good flowing bronze. A red clay crucible may not survive, but it is still worth trying out to see what happens!
umhaaois 1 year ago
You call that a knife?
topsy420 1 year ago
@topsy420 - No, I call that an Irish Bronze Age axehead.
umhaaois 1 year ago
@umhaaois I see you've played knifey spooney before
topsy420 1 year ago
those bellows are weird...
mittensthesnipercat 1 year ago
do you get your mineral from mining them or are they store bought?
Youcantbeseriousa123 1 year ago
@Youcantbeseriousa123 - we have not yet had the opportunity to use mined ores. which would be nice! The copper is generally electrical copper wire from recycling (almost 100% pure copper) and the tin is bought in ingot form. By weight we generally use roughly 90% copper to 10% tin.
umhaaois 1 year ago
what do you use as crucible
Henrik4950 1 year ago
@Henrik4950 - That is a handmade crucible. It is a mixture of high firing clay & sand. It may also contain fine "grog" and a very small amount of vinegar to add flexibility to the mix. These can be quite difficult to make as the mixture is NOT very flexible. You can Google "crucible recipe" to get some pointers.
umhaaois 1 year ago
@umhaaois thx
Henrik4950 1 year ago
a real viking axe
Henrik4950 1 year ago
those bellows are genius! i finnally found my design
panzuman 1 year ago
nice work!
thekinaesthetic 1 year ago
Wow that's really cool, so all it takes is essentially bags and air to melt bronze? That's awesome. This is a very interesting experiment you folks have going on.
unfortunatebeam 2 years ago
Nice one.
billymagfhloinn 2 years ago
vVery nice vid try pikemaking mountshannon
sparkymarkable 2 years ago
cool
lopez3486 2 years ago