What was the name of the refractory wash you used?

That is interesting. I would have thought that the silicon carbide crucibles would have a higher tendency to dissolve in molten iron and impart higher contents of silicon and carbon to it. After all, silicon carbide is used in commercial foundries exactly to that end, to raise the content of silicon and carbon of the melt. It's used because it dissolves easily in molten iron, and doesn't react with oxygen as much as either pure carbon or pure silicon thus the losses to oxidation at high temperatures are less.

@@luckygen1001 I've heard some use satanite refractory mortar as a furnace coating and as a crucible wash.

I've heard of people using slip investments as crucible liners...

@@luckygen1001 You can use almost any refractory that is dissolved in either water or alcohol. At the time we used a rammable refractory but powdered refractory is easier to make a wash with. Dissolve the refractory until you have a liquid that is easily paintable with a brush and will run into all of the nooks and crannies. Allow the wash to dry fully, give it a second coat and allow that coating to dry as well. As long as the refractory is rated for the temperatures you'll be reaching, it should help a lot. Still enjoying your videos, keep it up!

How are your crucibles holding up after all the iron melts that you do?

@@luckygen1001 I dont think I get that many melts per crucible. 35 would be pushing it, 25 is about the life span and then I use pliers to pinch off the thin edge to get a few more out of it. That may be because of the difference in our burners. I also use Morgan super clay graphite like you do. I have read that silicon carbide isn't necessarily a good option for iron. I've never used one so I what I read could be wrong. Also, I use a shank that's just big enough to wrap the base then I have two steel bars the height of the crucible welded to the shank base that the crucible lays against as I pour. I'll email pics later.

You bugger I was about to post "Sounds like a night out in Newcastle"

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I must try that one day. As I don't have satanite I will try zircon paint which I do have.

@@luckygen1001 Zircopax or superpax should work. I'm not sure it would hold itself together quite as well; I have some Superpax but haven't tried it for that purpose. The Satanite is much cheaper per pound too, and it has the consistency of mortar when properly mixed. It holds together very well. My propane fired melting chamber is lined with ceramic wool coated with 3 coats of Satanite too. It has held together beautifully for the past year and a half since I made it. (edit) maybe if you mix the zirconium silicate with a small amount of regular refractory mortar it would be more dimensionally stable. The satanite is rated for 3200F.

Were you using a flux with it? I found that bronze containing lead makes a very hard to remove slag after a melt.

@@luckygen1001 I didn't use a flux for the melt but resorted to adding Borax after to see if it would free the slag. Wished I hadn't! It made it worse! Trying to make the bronze was interesting but zinc addition to molten copper was an eruption. Am thinking maybe adding Brass to give the zinc content would be safer option. Alloy was 83%Cu, 7%Sn,7%Pb and 3% Zn.

Even normal materials at 2000°F degrade most materials. Oxidation gets us all in the end!

Read books by C.W.Ammen (casting iron)

I have never used a silicon carbide crucible.

For my small furnace the height of the crucible limits to how big a crucible I can put in there but you are right side clearance does matter so the tongs will fit in there.

@@luckygen1001 Thanks for that, just wondered if there was an optimal proportion for the efficiency of the melt. I will order one, I take it you find Salamander's the best quality/value?

From a backyard casting group im a part of - the recommendation from there is about an inch overall diameter as a minimum between the furnace inner diameter and your crucibles outer diameter so about half an inch and up to an inch gap on the radius which is more than enough for lifting tongs :)

@@lloydmilton Thanks for that I was just about to order one! I presume, like everything, there are good and bad crucibles and I was wondering if it was worth buying a Silicon Carbide Graphite one made in China or are they rubbish? I plan to do a fair bit of casting I want a reasonable life out of it.

@@MegaPoxie I cannot say if they would be rubbish or not, I use steel crucibles (oh the shame) for my aluminum melts, I don't do cast iron yet. That said I have a kilo of Graphite and a 5KG block of kaolin clay as well as some grog I want to mix and pressure form into a crucible for casting - when I get off my arse and make the mould for it :D Also before people get their tits in a knot over using a steel crucible for aluminum melts, remember these 2 things, I inspect the crucible prior to each melt, and I coat it in a fireclay wash to not only protect the crucible from the molten aluminum but also to reduce the scaling that occurs when you heat steel until it's orange hot. The steel I use is old fire extinguishers and without treatment they will fail after 4 - 5 melts, with treatment, i'm up to 10 melts on the current one and its still as thick as it was when I first used it but have not done any casting this year yet...

That is hard to answer just keep melting until the crucble is too thin to use.

I have never tried that.

It is important to keep the inside of the crucible clean otherwise it will build up over time and is harder to remove. To clean the crucible I use a 25mm X 5 mm flat strip of steel and bend it 90 degrees. I then grind a radius that is the same as the inside dia. of the crucible and use that to scrape off whats left in the crucible. I used to use a screwdriver but it can put deep scratches in the crucible.

@@luckygen1001 nice tool i will make one cheers. Do you do it while the metal/rubbish is still hot and flexible?

For cast iron I do it when the crucible has cooled down but for bronze and brass it has to be done when it is hot because I use a flux.

luckygen1001 ahhh thank you lucky. good to know what a pro does

I'm not sure but the glaze would dry quicker.

Borax is a great flux but it will eat away your crucible. Use only in small amounts.

The Morgan crucible in the video seems to hold up well to cast iron and most foundry suppliers have them.

@@luckygen1001 thank you very much sirSir for sharing and for pointing me in the right direction and for the super fast response.

Vesuvuis crucibles are the best but may be harder to get, next best is morgan crucibles.

@@luckygen1001 Hi. first thank you for sharing your knowledge with others. A question, what number or size of crucible do you recommend to melt pieces of 20 kg? They are for making weight plates for the gym and the heaviest is 20kg. In advance, I would be grateful if you could guide me in this regard. Regards

Ecramer@bex.net

As I showed the crucible with the glaze flaking off the material underneath was effected by the flame. Also some crucibles seem to be affected more by the flame than others.

You would have to ask the people who make the crucibles.

Yes you can.

I used to get my crucibles from refractory and ceramic but they have changed their name to Skamol Australia. Their website gives all the contact details.

@@luckygen1001 thankyou. Yes I looked up refractory and ceramic, still listed but there web link was dead. Will check under the new name. Thankyou for your quick reply👍

The harder and denser the metal is the ring lasts longer. If you made a bell from lead it would not ring at all because it is too soft.

@@luckygen1001 well what could I alloy with the aluminum to make it harder?

@@jondoes8222 Silicon makes it harder but it also makes it more brittle.

Scrap off all traces of iron oxide slag until you can see the clay graphite surface inside the crucible.

If you now how bulid a good nossle system you can use diesel.

@@jbone9900 Thanks. Do you have a link for a video on that?

What will we do

Yes it is.

! gram of iron should dissolve slowly in copper at that temperature.

Cast iron scrap is very close to the eutectic point and will not absorb the graphite from the crucible. If it did absorb graphite it would have to dissolve the clay and then eat a hole in the crucible which it does not.

I tried and failed!

I have had a go at making my own crucibles and all were failures so I cannot help you there. You could try watching youtube videos on how to make crucibles.

Yes I use salamander super clay graphite crucibles and I don't break in crucibles.

So true, fluxes can shorten the life of a crucible.

@@luckygen1001 I'm glad someone else agrees. At the silver refinery where I work, the tilt furnace operators are changing out a 300# crucible every other day. The old timers are blaming the new guys, saying they're dropping the 70# ingots into the furnaces. I say look where the hole is. It's at the top of the crucible just below the spout where the level of molten silver is, look at how many shovel full of borax you're throwing in there. Those guys will add borax to thin out the melt then add sand to thicken it up.

KZfaq will not let me change my email so I can be contacted. If you want to put your email address in your reply and then I can contact you. I was in QLD about six weeks ago visiting the steam show at old petrie town.

KZfaq will not let me fix my email problem.

@@luckygen1001 Is it possible for you to write your email here in the comments as an associate of mine needs a casting job done, and i have no way to contacting you.

I like to keep my email address private. I only do castings for myself but thank you for asking.

If you need or know someone to build some foundry fabric in Canada please mention me

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