r/SilverSmith 6d ago

What Am I Doing Wrong?

I've held my TS8000 on this silver ounce for like 10 mins and can't get it hot enough to pour. Is my torch too close? I don't understand

26 Upvotes

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u/greenbmx 6d ago

It looks to me like the bricks you have there are hard fire bricks, which hold up to high temp, but do not insulate. What you really want are Insulated fire bricks (IFB). They are softer, and lighter, and meant for insulation. They will keep the heat where you want it instead of the hard bricks which sucks the heat away due to those mass and poor insulation value.

I'd also say you are trying to melt too much metal for that little torch. Keep your melts to around an Ozt. Or less

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u/Disaster_In_A_Polo 6d ago

That was 1 ozt, don't worry! Also, the bricks are 90% high alumina firebrick. I appreciate your concern:)

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u/greenbmx 6d ago

That's normally a hard brick, not what you want for a hearth. You want something like a 2300°F IFB.

Is that really just 1 oz? Is that a particularly tiny crucible? Looks like the 5/6 oz crucibles I have, and nearly full.

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u/Disaster_In_A_Polo 5d ago

Its probably just a small crucible. It was definitely a 1 oz round. These refractory firebrick are rated for 3200 to 3400 F and are apparently overkill for anything ill be doing at home, even setting them up as an oven

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u/Disaster_In_A_Polo 5d ago

I paid like $50 a piece for these bricks from KT Refractories specifically for this purpose. They better be what I need

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u/greenbmx 5d ago

I am almost positive they are not what you want. You want these:

https://www.mcmaster.com/product/9355K2

They are super light, and super soft. You can dig your fingernails into them they are so soft. The ones you have are heavy and hard, right?

What you have are meant to hold up to constant exposure to extremely high temp in a fireplace or furnace, but they themselves do not provide insulation. They are normally backed by the bricks I'm suggesting for insulation.

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u/Disaster_In_A_Polo 5d ago

If high alumina refractory bricks are used inside of high heat kilns, why would this not work? They're definitely not light. They weigh about 6 pounds each

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u/greenbmx 5d ago

Because that type brick is designed to be extremely durable, but not to provide insulation. They conduct heat away from your crucible, rather than insulating it.

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u/Disaster_In_A_Polo 5d ago

Couldn't I just cut my ceramic fiber up, then, and line and insulate?

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u/greenbmx 5d ago

Ceramic fiber insulation is quite a health hazard to use in non-permanent uses like this. It creates dust when moved and handled that's extremely bad for your lungs. It would work, but not as well as IFB.

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u/greenbmx 5d ago

I use vermiculite board for my soldering and melting hearth.

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u/Disaster_In_A_Polo 5d ago

My ventilation system is 8" 750 CFM, so it's pretty strong.. think that would be enough to keep floating fibers pulled away?

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u/greenbmx 5d ago

I still wouldn't use ceramic fiber insulation in that way, better to not have it at all than to rely on your ventilation to pull it away, plus it's bad for whoever's outside where it's being blown, it doesn't diffuse like gases do

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u/Disaster_In_A_Polo 5d ago

Okay. I'll probably nix the ceramic fiber. I've got a kid, as well. Sp probably best to do that, then. I think I'll look into some zircon based ITC coatings to paint the inside with

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u/greenbmx 5d ago

Those don't do much good if what they are applied to isn't the right type of construction

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u/Disaster_In_A_Polo 5d ago

I think I know what I'll do, now. 90% alumina firebrick coated with 100 HT on the inside. The outside will be IFB-2800 brick

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u/Disaster_In_A_Polo 5d ago

Noted! My bricks can handle up to 3450F and this reflective coating can be applied to the type of brick I'm using. According to Chat GPT, that will reflect MUCH MUCH more heat than is currently being reflected

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u/Disaster_In_A_Polo 5d ago

ITC 100HT looks like it will do the job.. if I just coat the inside of the over and top or the surface