Basic Soldering Question

[Rylkan]

Hi All:

I've been slowly practicing how to make a ring and had a few questions for the experts on soldering technique.

In case this helps, my materials:
===============================
18 gauge Sterling Silver/Copper Mokume gane sheet (http://www.reactivemetals.com/http___www.reactivemetals.com/Home.html) ((I plan to use a different metal ultimately. This was just a nice affordable metal to practice with. ))
Hard Silver Solder Wire
Self Pickling Flux (http://www.ebay.com/itm/161353292370) (( I wasn't sure how much an effect self pickling flux would have, but I decided to give it a shot. ))
Pickling Compound (http://www.ebay.com/itm/181367078473)

Shaping and working the metal has been fairly straightforward so far. My issue came when I tried to solder the ring closed. I applied the flux to the ring (Once by submerging it into the flux for about 15 seconds and once by coating the ring)) and let it sit for awhile. In both cases I saw nothing that signified to me that a coating had taken to the metal. Still, I decided to experiment and used my butane torch to solder the ring closed and got tons of scaling for my effort.

I've done some reading on soldering metal but I wanted to make sure I wasn't missing something. My understanding was that the flux will protect the metal as it undergoes heating so you do not get any scaling. And then the pickle will remove the flux. Seems straight forward, but something about my setup isn't working correctly.

Thanks for the help everyone!
Rylkan

[ps_bond]

Firstly, I would not use hard solder with Cu/Ag mokume. You need a medium or easy solder for that mix.

I don't know that flux, I assume it's a thin liquid like Auflux - which I have to admit I'm weaning myself off, going back to borax. I'm intrigued that the seller claims it's good for platinum - 1) using flux on platinum will contaminate the joint and 2) I strongly doubt it is capable of performing at those temperatures. Anyway, clean metal will help the stuff coat the surface, but it's only really needed in the area of the joint. Flux is there to prevent oxides forming on the metal and allow the solder to flow, I'd still expect some scaling whether it's burnt flux residue or surface oxides. The piece is then put into pickle to remove both.

Finally, if your torch can't get the piece hot enough quickly enough then all that will happen is your flux gets used up before the solder flows.

[Dennis]

Peter has already covered most points, but I would like to emphasise that if you are using a refillable mini torch, it might not be hot enough for the size of this ring.

You can improve matters by building a little kiln with soldering bricks, to retain and reflect the heat and also by using two torches together, one in each hand.

The join will also tend to open when the ring is heated, and the solder will then not bridge the gap. This is avoided by using binding wire, either across the ring, or along it with a bridge at the join. It also helps to apply heat to the part furthest from the join, so that expansion tends to close the gap.

Ultimately you will have to consider a bigger torch. Dennis.

[Rylkan]

Firstly, I would not use hard solder with Cu/Ag mokume. You need a medium or easy solder for that mix.

I don't know that flux, I assume it's a thin liquid like Auflux - which I have to admit I'm weaning myself off, going back to borax. I'm intrigued that the seller claims it's good for platinum - 1) using flux on platinum will contaminate the joint and 2) I strongly doubt it is capable of performing at those temperatures. Anyway, clean metal will help the stuff coat the surface, but it's only really needed in the area of the joint. Flux is there to prevent oxides forming on the metal and allow the solder to flow, I'd still expect some scaling whether it's burnt flux residue or surface oxides. The piece is then put into pickle to remove both.

Finally, if your torch can't get the piece hot enough quickly enough then all that will happen is your flux gets used up before the solder flows.

First off, thanks for the reply.

I plan to ultimately use a white gold/sterling silver mix, since I know that is more in the taste of the person I intend to give the ring to. The hard solder was mostly purchased for that purpose. Would you recommend it in that case then? My understanding was the hard solder was better for those sorts of metals and will make it easier to resize the ring in the future if needed.

As for the flux getting used up in heat, how quickly does that normally take? Or is it too difficult to ballpark that sort of thing? I have a mapp torch, but the solder melts far too quickly for me to make sure it is fully securing the joint. It just runs off and pools up in the wrong place. (Probably no doubt made worse by poor technique on my part.)


Peter has already covered most points, but I would like to emphasise that if you are using a refillable mini torch, it might not be hot enough for the size of this ring.

You can improve matters by building a little kiln with soldering bricks, to retain and reflect the heat and also by using two torches together, one in each hand.

The join will also tend to open when the ring is heated, and the solder will then not bridge the gap. This is avoided by using binding wire, either across the ring, or along it with a bridge at the join. It also helps to apply heat to the part furthest from the join, so that expansion tends to close the gap.

Ultimately you will have to consider a bigger torch. Dennis.

Thanks for the help. Only one question. If I were to do it this way, and heat from below so expansion works in my favor, would that burn the flux off too quickly? Or am I just misinterpreting how quickly that burns off now?

[Dennis]

If you are using borax, it will long outlast the time needed to make jewellers solder flow, provided your torch is upto the job.

For instance a ring made from metal strip, say 10.0 mm wide and 1.0 mm thick, might take 40-50seconds to solder.

If the air holes of your torch cannot be controlled to make the flame slightly bushy (less fierce), then you must keep the torch moving to avoid concentrating on one section for too long.

It helps to solder in semi darkness so that you can see and avoid hot spots. It also helps to get some practice in using a cheap base metal, such as copper or brass. Dennis.