Sunday, May 10, 2015

Smelting - from offcuts to metal ingots

©2015 Fiona Dempster - Silver-plated copper begins to melt at 1085C
On Friday I did my first metal melt with my small electric furnace. In Friday's post I shared some of the outcomes of that experience - not perfect but a good first effort and a lot of lessons learnt.

The whole process really started because I wanted to use the small and odd shaped silver plated offcuts (silver over copper and silver over brass or EPNS). Since I purchased the furnace a couple of weeks ago I have been cutting some offcuts into small fragments that would melt more quickly in the furnace. I have kept the pieces in separate buckets - silver over copper; and silver over brass.

©2015 Fiona Dempster - Small pieces of silver-plated copper
The furnace is quite compact - the biggest crucible I have is supposed to hold 3kg of molten gold when full. The crucibles are solid graphite - which I had cured during the week - takes a couple of hours.

©2015 Fiona Dempster - Small electric metal melting furnace
©2015 Fiona Dempster - Cured graphite crucible full of silver-plate offcuts
My first smelt was with the silver over copper. These were place in the crucible; and were topped up when the metal started to melt at about 1100C. Pouring was a new experience - white hot crucible held with tongs and leather glove. But lovely to see the metal running into the graphite moulds which had been heated but not fully cured.

©2015 Fiona Dempster - White hot crucible - metal and borax flux fumes being given off - all the more reason to do this outside on a solid tiled and well ventilated work area
©2015 Fiona Dempster - Molten metal 
As you can see from the heart shot - the mould was basically on fire with the heat of the metal - it did not burn second time around as it had cured.

©2015 Fiona Dempster - Heart on fire - graphite mould curing itself!!!
The hot metal needed to be quenched in water - still very very hot even after setting.

©2015 Fiona Dempster - The silver-brass heart quenched
And the outcomes look pretty grubby initially; but as you know from Friday's post they polish up well.

©2015 Fiona Dempster - Front of the silver-copper heart in the rough on rust
©2015 Fiona Dempster - Back of the silver-brass heart on wood after quenching
Some of the lessons learnt include: good to have two pairs of hands; good to direct gas flame onto the mould and the pouring metal so it stays nice and liquid; good to have a full face mask to deflect the heat; and good to have moulds with wide apertures when one is a rank novice. Still I'm sure the second round in a few weeks time will be interesting.

Thanks to Fiona for the photos (and there are many more) - but next time I think she will be the second pair of hands.

The metal is an amalgam of silver-copper and silver-brass - both have there own rich beauty.

5 comments:

  1. the process is fascinating and i thank you for sharing it... what i love is how the metals separate with the temps - the beautifully reticulated silver sitting atop its base... body and soul... individual and yet joined... they hold hands so wonderfully.

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  2. I've always wanted to do this but I think I can now be satisfied to know that you're doing it Barry. What a wonderful process to see through Fiona's photos!

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  3. Hi MJ and C - thanks for your support and encouragement - I loved doing this - and am excited about the serendipitous nature of the whole process - separate but joined - I like that. C - maybe one day when you visit can have a play with metal. Go well. B

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  4. so interesting to see how serious working with hot metal is...and looking at your photos i kept thinking i might see the hands of another underground-dwelling person come to visit and help you out. once on a camping trip with hooligans and adults (all male) one guy carved a little wooden mold and heated up some found metal, poured it in, and made a little beadlike thing. i was fascinated. on that same trip one of the fire-pit rocks split in half with a big sound. we all returned safely.

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  5. ooo ... it's interesting how the surface of the heart turned out. Like reticulated metal. Super cool (or hot) and so very fascinating!

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Comments are welcomed - it is good to connect with fellow travellers.