# Silver cement not melting! New blowtorch needed?



## NewBullion (Jul 15, 2011)

Hi everybody.... (Hi Dr. Nick)

I tried melting some silver cement for the 1st time (about 20g to start) with my new Bernzomatic Quickfire blowtorch and melting dish to make anodes for my silver cell. After convincing myelf, the blowtorch wasn't going to blow my hand off, I began to "melt". The powdered cement turned orange with heat but not for long. As I moved the blowtorch around to other areas of the dish, the orange areas cooled very quickly. Some seems to have turned molten (more like some just stuck together into a blob) but then cooled quickly even as it was heated and then this reddish substance appeared. I then took another dish and put in 10g of cemented silver. After 20 - 25 mins of pointing the torch at one area, realisation kicked in that no melting was happening today, I decided to stop before I ran out of propane. Tiny amount of Borax was added when molten for a matter of seconds. 
Is the blowtorch just not hot enough? I was told it would be and it's supposed to reach 1500C. I was told Mapp gas cans would fit these torches. 
Any advice as it should be melting at least small amounts like 10g? What is the reddish substance? 
Will get an oxy/acetylene setup when Im more savvy with my melting skills. I have over 1200g of 925 to refine but practicing with 50g first.

I thank you all in advance. I'd be more worried if everything was going right for me :lol:


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## goldenchild (Jul 15, 2011)

You should use MAPP gas. Oxy/Acet will work but not needed for silver.


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## NewBullion (Jul 15, 2011)

goldenchild said:


> You should use MAPP gas. Oxy/Acet will work but not needed for silver.



Thank you. Will get Mapp gas in the morning. Quite hard to find in UK.


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## Sodbuster (Jul 15, 2011)

NewBullion :

I would guess that you have unconverted silver chloride in the mix. But you stated "I tried melting some silver cement " so that shouldn't be the case. 
I'm no expert, but I have melted up a few pounds of silver buttons. I do remember a batch of silver converted from chloride (incomplete conversion) that I tried to melt, and suddenly the torch didn't seem Anyways near hot enough. It stained up my dish with some of the same grayish colors I see in your picture.That may explain some of the reddish colors your looking at also. If it smoked allot when you attempted to melt, then you most likely somehow included some chlorides in the mix. 

From your picture, it don't look to me like you have enough flux in their. It is up to the flux to collect the impurities from the melt. Your dish needs a lite coating over most of the inside surface before you start the melt. 

From your picture it looks like any impurities are just sticking to the surface of the molten metal and the unglazed portions of the dish. 

Don't be afraid to use a little more flux, The flux also transfers the heat more evenly in the melt. It's as if the metal the dish and the flux all have to become one. Only when all three reach melt temp will you get a nice button. 

If your torch can not heat a red spot about 2-3" diameter in the bottom of an empty dish then you will need a better torch, or a hotter flame. Does your torch have a really defined flame that comes to a pencil point? Those type of torches never seem to be able to heat a larger area at once, you will have to move around allot.
I use an old style naturally aspirated dual fuel Turbo torch with mapp gas, the one with the swivel neck, before they added the tick lighters. It has no problems melting a 3oz button. 
Just some ideas. 

Ray

PS: the definition of an Expert
The x is a sign of excellence, and the spurt is just a drip under pressure.

So I could be an expert.


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## Oz (Jul 15, 2011)

I use a very thinly flux coated dish with no additional flux added when I melt and cast cement silver into anodes for the silver cell.

I have no clue on the red you are getting.


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## NewBullion (Jul 15, 2011)

Sodbuster said:


> Ray
> 
> quote]
> 
> ...


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## NewBullion (Jul 15, 2011)

Also the flame coming off the silver was bright green & bright yellow (a different yellow to a standard flame). 

I will solve this problem or go broke trying........


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## Barren Realms 007 (Jul 15, 2011)

Everything you are describing indicate that you still have some copper mixed with your silver. The green color of your flame is the final key.


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## butcher (Jul 15, 2011)

I agree copper in mix, as the dish cracking, you are probably thermally shocking it (changinging temperature too rapidly, it is not expanding and contracting slowly uniformly with heat changes).


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## juxtaposedsoul (Jul 15, 2011)

First of all, I am no expert. Barren Realms 007, GSP, Harold and the likes can give much more insight. However, from my limited experience I can tell you two things: first, you do in fact still have some contaminates in your silver powder. Try rinsing with distilled water, or even boiled tap water, after cementation and filtering. There seems to be some copper in your powder. If your nitric is too strong, or you forget to dilute it 50/50 after dissolving your silver, it can chew up a lot of copper which can allow a few stray electrons to bind with your silver cement. You want very little free nitric during cementation. Secondly, melting silver is not as easy as it would seem. I have spent 30-35 minutes to get one ounce properly melted, sometimes having to re-melt it after pouring because it solidified during the pour. It is tricky, but practice makes it easier. I use a Bernzomatic TS with the 4 foot hose and run MAPP, and my silver will not stay molten more than 2 seconds if I remove the flame. Tricky stuff, but it looks soooo beautiful when all the hard work is done.


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## Sodbuster (Jul 16, 2011)

"Washed the cement with tap water as was suggested in many posts."

Did you get a white cloud (like milk) when you introduced the tap water? 
Did you have allot of white/gray smoke from the melt?

If your silver wasn't completely cemented you will get some chlorides at this point.
Look for white grains in your cemented silver, use magnification if you have to. 
I may be wrong but I just feel that from what I've seen in the first pictures that you have chlorides present. But pictures have lied to me before.

As others have stated, you have obvious copper ( bright green ) in the mix. that alone will change the way it melts. I think your biggest problem is inadequate heat, and improper fluxing of the dish. Like I said, If you can't maintain a red glow in the bottom of an empty dish with the torch, you will need more heat to come close to a pertly button.

Be sure and have a look at LaserSteve's website. Some good videos. One demonstrating how to properly season your melting dish.

I may be wrong but from what I understand here on the great GRF you won't want to melt values in cast iron or graphite. They make good molds, but you should not melt values directly in them. 

Hope this helps
Ray


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## Harold_V (Jul 16, 2011)

Oz said:


> I have no clue on the red you are getting.


I do. It's copper (oxide).

Harold


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## Harold_V (Jul 16, 2011)

The solution to this problem is to use an adequate heat source. A propane torch, even one using MAPP gas, is just a dodge that is troublesome. Because silver transfers heat readily, it is rapidly radiated from the heated object. While the temperature of a propane torch is adequate to melt silver, the volume of heat required (BTU's) is woefully lacking. 

If any of the readers are serious about refining and melting, an oxy/acet torch is almost mandatory. You can substitute acetylene with either natural gas or propane from a large cylinder, but you're kidding yourself if you think you can get by with a small propane torch. It simply is not up to the task, regardless of how you rationalize its use. 

There is no reason in the world that you should take more than one minute to melt a troy ounce of silver. The idea that one would spend tens of minutes doing the task is more than enough evidence that you are not on the right track. 

Harold


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## qst42know (Jul 16, 2011)

> The torch could be better but seems hot enough to crack the clay dish.



Your dish properly preheated is unlikely to crack from being over heated. Excluding contaminants in your cement, not getting the "dish" itself hot enough may be part of your trouble. Make the dish glow or your metal will freeze where it sits.


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## Oz (Jul 16, 2011)

Harold_V said:


> Oz said:
> 
> 
> > I have no clue on the red you are getting.
> ...


Yes Harold, I am an idiot, hindsight is 20/20. I was thinking of “cement silver” as 98%+ in silver purity. The idiot I am, I never considered there could be over 10% copper in the alloy to give even a slight red coloration to the melt.


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## NewBullion (Jul 16, 2011)

Sodbuster said:


> Did you get a white cloud (like milk) when you introduced the tap water?
> Did you have allot of white/gray smoke from the melt?
> 
> Be sure and have a look at LaserSteve's website. Some good videos. One demonstrating how to properly season your melting dish.



Im dissolving this mess in approx 1.2ml Nitric / 1.2ml H20 per gram of silver and will cement silver out again with copper after diluting mixture.
I washed my remaining cement I thought was clean, because when washing it with H20, the water ran clear eventually. I put 200g into a filter, packed it down, poured in boiling tap water, and watched this yellow fluid drip out. Some small particles fell through into the cup, looks like cement, but it's orange. Guessing this might be copper. Amazed at how dirty my cement was (if these are contaminants) and how the orange particles have appeared.
There was no white smoke or white cloud when washing with tap water.
Thank you everybody for all your help. I hope somebody finds this useful one day. I'll keep everyone posted. I checked out LS website a few weeks ago and the vids wouldn't play for me. Can you believe I had to resort to the ancient art of reading books :shock: It's been a while.


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## juxtaposedsoul (Jul 16, 2011)

Too much time melting silver. Great point Harold, not just for me but for anyone spending a lot of time over the melting dish. A new torch has just went to the top of my list. One minute to melt an ounce? That would be awesome and well worth the money spent for a new torch. I'm guessing that an oxy/acetylene torch would also make it easier to pour the silver because it would stay molten a little longer?


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## goldenchild (Jul 16, 2011)

juxtaposedsoul said:


> Too much time melting silver. Great point Harold, not just for me but for anyone spending a lot of time over the melting dish. A new torch has just went to the top of my list. One minute to melt an ounce? That would be awesome and well worth the money spent for a new torch. I'm guessing that an oxy/acetylene torch would also make it easier to pour the silver because it would stay molten a little longer?



On my youtube channel there is a video of me melting and pouring 10 troy ounces of silver with MAPP gas. So oxy/acet will definitely do the job. There is also a video of me shooting silver using an oxy/acet rig. I chose the rig that time because the metal has to be hot enough not to freeze in the receiving crucible.


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## Harold_V (Jul 16, 2011)

Oz said:


> Harold_V said:
> 
> 
> > Oz said:
> ...


There need not be a high percentage of copper to yield the red coloration. Because the silver has been heated for a prolonged time, and without a flux to absorb the copper (which would then be blue instead of red), the traces of copper have oxidized, and are no longer absorbed by the silver. Fluxing, when melting silver to be cast as anodes, is actually quite important, as it is part of the purification process, removing oxides, and "lubricating" the silver so it gathers well. 

Note that I recommend one NOT use soda ash as part of the flux. It tends to reverse the absorption of oxides, causing them to remain in the silver. 

Harold


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## Harold_V (Jul 16, 2011)

juxtaposedsoul said:


> I'm guessing that an oxy/acetylene torch would also make it easier to pour the silver because it would stay molten a little longer?


A great deal depends on the flame you select, and the tip you use. Silver absorbs oxygen at a frightening rate (nine times it's volume), which it expels upon solidification. That means you should use a neutral or reducing flame, which is much cooler than an oxidizing flame. You run the fuel rich for a reducing flame, so there's no free oxygen. 

The torch I used to use was a large Hoke torch. I have been unsuccessful in finding them, so they may no longer be on the market. Mine was purchased about 25 years ago. It had a large rosebud type tip, so that may serve as a guide for you. A rosebud tip is key to success, whereby you can melt large volumes of metal easily because you produce the required BTU's. If you have natural gas service, it might pay you to investigate a torch that can be so fueled. Acetylene is quite expensive, and not a necessity. Key to achieving the required heat is the use of oxygen---the fuel type is secondary. Consider using propane if you don't have natural gas. 

Harold


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## Harold_V (Jul 16, 2011)

NewBullion said:


> I washed my remaining cement I thought was clean, because when washing it with H20, the water ran clear eventually. I put 200g into a filter, packed it down, poured in boiling tap water, and watched this yellow fluid drip out. Some small particles fell through into the cup, looks like cement, but it's orange. Guessing this might be copper.


Guess again! 8) 
I think you'll discover that if you put a drop of HCl on the yellow material, it will dissolve instantly, and yield a hint of green. 

It's iron. 

Rust. 

Harold


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## juxtaposedsoul (Jul 16, 2011)

Thank you, Harold. I am certain your advice on torches will benefit not only myself, but also New Bullion and others who are trying to find the right way to get things done. I do not have gas service at my home but I can certainly buy a combo torch rig at Lowe's or Home Depot. In fact, I will be doing so tomorrow as I am wasting time and MAPP gas with my current set up. I have heard many people say that MAPP, propane, propylene and even butane fuels work well for melting silver, but in my experience they do not. I have tried 3 of the 4 with limited success and it is frustrating. I believe the cost of the oxygen will even out with the use of less MAPP because of quicker melt times. Even if it does cost more to run a combo set up it will be worth it just on the time I will save on the many, many melts and castings I plan on doing. I will look at torches with interchangeable tips, including a rosebud.


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## element47 (Jul 17, 2011)

Many years ago I bought a National 3A torch (usually called "blowpipe") for almost nothing. They are about $100 and have been made since the 30's, unchanged since then. I just bought an assortment of 5 tips for $28 on ebay, some oxy-fuel and some rosebuds. These torches, depending upon the tip selected, can use nat'l gas + compressed air, NG + oxygen, propane + oxygen. I am a tad concerned that the neck of the torch is a little short and might cause my hand to feel a lot of heat, especially under oxy+fuel use, but we shall see. They can even use NG at "house" pressure" which is very low. 

I have tried using MAPP gas to melt silver and I simply don't see the feasibility. I see people melting metal in YouTube videos but I have never been able to do so in a way that makes me happy. And MAPP is expensive. You shouldn't have to spend 10+ minutes heating your work. If you do, you're underheated. I have *never* been impressed with MAPP gas. Plus, with a gas + air torch, you really do not have the opportunity to produce a reducing flame which as Harold pointed out, is handy for silver. I have read the specs, intellectually I know MAPP dumps lots more BTUs into a piece of work than does propane, but it has never floated my boat. 







If I didn't have this torch body, I would probably recommend a new buyer purchase a brand new light-duty oxyacetylene set, including regulators, but to run the thing on oxygen and propane. Which just means selecting the proper tips. Plenty enough heat The fitting into the fuel cylinder USED TO BE the same, between actylene & propane but may not be any longer, as propane tank-fittings have changed over the past few years.


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## Harold_V (Jul 17, 2011)

I agree that the length of that torch may be somewhat undesirable. It will likely serve well for small volumes, but I'd hesitate to heat several ounces, and I definately would not recommend it be used to melt palladium and/or platinum. 

Nice torch, by the way. Too bad it's not somewhat longer, to get you away from the heat. 

Here's a picture of the torch I used to use, to give you an idea of how long it should be to provide comfort. Sorry for the cluttered picture, but it's the only one I have. 



Harold

Upon edit: You may be able to use an extension on the brass body, moving the tip out. That's all that would be required to make it a fine torch. Looks like it would be easy to make.


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## qst42know (Jul 17, 2011)

There are plenty of rosebud type tips on the National (Premier industries) torch site, even In stainless steel.

The tube for their hydrogen torch version is much longer than the standard torch. They do sell extensions.

http://www.nationaltorch.com/tips.html

http://www.nationaltorch.com/Tipexelb.html


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## element47 (Jul 17, 2011)

Yes, National sells all kinds of everything for the torch, but you will find their prices very expensive, particularly for individual pieces. The torch body alone is $100, that's with no regulators or hoses or tips. In any other circumstances I would not be going this route except I bought the torch body with a NG + air rosebud brand new unused for like $3 at a garage sale...I couldn't resist it. The 5 tips I just bought on ebay for $28 are about $14 each * 3 qty and $25 each for 2 rosebuds. 

I would just buy a smallish oxy-acetylene set complete with regulators and hoses and be done with it. That's what it looks like Harold has. You can buy a complete US-made set for under $200, handle, tips, hoses, regulators, brand new. I'd also suspect you could find a very lightly used set with medium-small tanks for very little more than that. I think it is only the cutting and rosebud tips that are different for oxy-propane vs oxy-acet. I would try to do research as to what the manufacturer of any used (or new, for that matter) set offers for propane, where can get them, and what they cost. Pretty easy. And as I said, you might have to change the input stem to the fuel regulator if you want to use propane. The fittings used to be identical propane > acet but they have changed just in the last 5 or so years.


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## Palladium (Jul 17, 2011)

I was at trade day this morning and saw a guy with complete set ups for acetylene for sale. They were used of course but in good condition. $200.00 would have gotten me the cart, the bottles, regulators, 50 ft hose, a striker, and the torch with my choice of a new head. A deal anyday !!


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## element47 (Jul 17, 2011)

That's a good bit better than a typical deal, but there you go. With a lightly used rig, you can get a cart and those tanks "thrown in". You may have to buy a tip or two, but if you do, then those are nice and new. You'll almost certainly have to buy new oxy-propane tips for any rosebud work and to cut steel if you change the regulator over to propane. The cart is a VERY nice thing to have, not just because it helps move the tanks around, but it makes it easy to tie the cylinders to an upright so they do not fall over in use. That can be extremely dangerous, a tipped over oxygen tank whose valve gets knocked off will turn into a torpedo and can blast through a concrete block wall. Needless to say, that could cause serious injury. One way or another, be religious about tying up your tanks! 

Also important: Make sure that there is a date stamped into the oxygen cylinder that is within the last 5 years. If the tank is "out of test date" then nobody will fill it without testing it. If it is close to the expiration of the test date, then it may be smart to take it to a gas supplier and exchange tanks even if it isn't empty. *Don't let your oxygen tank get out of test date. *

Second, and there isn't a wonderful way to do this, ask the seller if the tank is an "ownership" tank. This means that the seller basically owns it and brings it back to the gas supplier and takes away an equally-sized, filled tank, but a DIFFERENT tank. What you want to find out is whether the tank is stolen, but you have to ask delicately. Just ask "where do you get these filled". Probably answer: "Any gas supplier" = meaningless. Try to ask in a way where you find out if the seller ever had the tank refilled and what it cost. 

Acetylene tanks generally do not go out of test, since they are rather low pressure. Smaller tanks do NOT have the screw-on safety caps. I always preferred the minimum size that had those safety caps on them. Yes, they could be 3 lifetimes of supply for the small PM guy, but safety is something we talk about around here and I am big time in favor of it.


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## peter i (Sep 24, 2011)

In Denmark the rules are strict and the prices disgustingly high when oxygen and acetylene bottles are concerned.

LPG on the other hand, is no problem as long as you do not go above 11 kilo bottles.

I have been doing all my gold and silver melting with an LPG burner (Sievert cyclone burner) of the type used by plumbers to hard solder copper tubing.

When you want to heat something, you need to have:
*- temperature* But that is really not a problem: A candle flame is easily 1100 degrees centigrade, any burner flame is warmer. They should all do the job, right? But no;
*- wattage*: And here is the first problem. Your burner needs to deliver more heat than is lost from your target. The radiation energy per unit time from a "blackbody" is proportional to the fourth power of the temperature. In plain speak that means, that once your target is glowing, you loose a lot of heat. In a furnace, the radiation is kept inside, but in a melting dish, you need to put in a lot of heat!
- *concentration of the heat*: In my opinion, this is where oxy-acetylene (and oxy-LPG) wins: It makes a small concentrated, hot flame. A traditional LPG-burner is too fuzzy. The cyclone burner is hot and concentrated. It is not as fast and hot as the oxy-acetylene, but it does a nice job.


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## bmgold2 (Jan 20, 2014)

goldenchild said:


> juxtaposedsoul said:
> 
> 
> > Too much time melting silver. Great point Harold, not just for me but for anyone spending a lot of time over the melting dish. A new torch has just went to the top of my list. One minute to melt an ounce? That would be awesome and well worth the money spent for a new torch. I'm guessing that an oxy/acetylene torch would also make it easier to pour the silver because it would stay molten a little longer?
> ...



I know this is an old message and this is probably not the video goldenchild is talking about but it explains about why silver doesn't melt when using a propane torch and shows how to do it.

[youtube]http://www.youtube.com/watch?v=ZFPZK0w-gso[/youtube]

Trick is kaowool or ceramic fiber insulation. Lasersteve used to (and probably still does) sell a small firebrick furnace to melt silver/gold using a propane or mapp gas torch. Same idea...insulation.


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## saadat68 (Nov 28, 2017)

Hi
I tried melting 400 gram silver cement for the 1st time. Not melting after 2 hour
I saw green flame so after one hour I added one spoon of *Sodium bicarbonate on the melt* and put it in the furnace again for another hour.

My furnace was red
http://uupload.ir/files/gov_img_20171128_171111.jpg

After 2 hour:
http://uupload.ir/files/n8bb_img_20171128_173158.jpg

http://uupload.ir/files/z3th_img_20171128_173713.jpg


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## goldsilverpro (Nov 28, 2017)

From the color, it sure doesn't look hot enough to me. Silver melts at 1763F (962C). To give a little time to pour it, before it solidifies, I would heat it to about 1800F (982C) or so. On the temperature color charts, 1800F (982C) tends to be a bright yellow-orange color. Your photos show somewhere around a semi-bright red color, maybe with a little orange in it, about 1500F (816C), more or less. By eye, this color thing is not rocket science, but I think your melt is more red than anything. Pick your poison on these charts. None are perfect and no two are exactly the same.

https://www.google.com/search?biw=1138&bih=514&tbm=isch&sa=1&ei=U6YdWr6pAsvBmwG7o4ygCA&q=molten+temperature+color+chart&oq=molten+temperature+color+chart&gs_l=psy-ab.3...129602.144482.0.145233.17.17.0.0.0.0.158.2335.0j17.17.0....0...1c.1.64.psy-ab..0.7.1026...0j0i13k1j0i8i7i30k1j0i7i30k1.0.ZfvobcOJ300


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## FrugalRefiner (Nov 28, 2017)

I posted a heat color chart in the Furnace Temperature Colors thread based on about a dozen different charts. It's not perfect, but it may help.

Dave


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## saadat68 (Nov 29, 2017)

Thanks
I couldn't reach to yellow after 4 hour!!! What is problem ?

Flame:
http://uupload.ir/files/ppcd_img_20171129_175716.jpg

Furnace: (After 2 hour I putted some glass wool in hole of the torch)
http://uupload.ir/files/2q7t_img_20171129_194514.jpg

It was orange tonight:
http://uupload.ir/files/yf21_img_20171129_185329.jpg

In youtube I see many videos of melting silver with a dish and mapp gass torch!!! 
Why I can not melt with a furnace ?
Also my silver be shrink. Did it evaporate ?


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## Palladium (Nov 29, 2017)

Your just below the melting temperature. Your not putting enough heat (Btu's) into the furnace. 
What you are seeing with the shrinking is called solid phase sintering and gives the clue to your problem you are asking about. The shrinkage is from the fusion process of the molecules where they move closer together almost becoming a liquid at the liquid solid phase transition temperature. Your almost breaking that temperature line of melting, but not quiet. The answer is either stop the excess heat loss or pump in excess btu's to heat the mass up. Just because you are reaching melting temperature with the burner doesn't mean it's pumping out enough btu's to overcome the thermal mass of the silver as a whole. A cigarette lighter flame burns hot enough to melt gold or silver, but the lighter can not produce enough btu's to overcome the heat loss or the combined thermal mass of the object your melting anymore than it can heat your living room. Silver metal clay is a sintered product. It shrinks 10-15 % on sintering without ever melting it. You can do it on a stove eye! It makes a solid without melting. Metal clays do the same thing. They do a lot of metals this way. 
https://www.youtube.com/watch?v=hPUJPXyUt3c


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## saadat68 (Dec 4, 2017)

Thanks
I am starting to redesign my furnace


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