Solder seam splitting

Hi
I am suddenly having lots of trouble with soldering 18ct yellow gold rings. I have made quite a few wedding bands like this over the years (1.5mm x 5mm sheet gold)and never had any trouble. However, now every time I gently shape the ring on the mandrel after soldering the ring is splitting along the solder seam. I am quite an experienced jeweller and have tried varying everything I can think of (new solder, different flux, cleaning everything like mad, different heating/ cooling regime) but just don't understand it. I have used the same solder panel as I've used to make previous rings, as well as trying brand new stuff. Sending me a bit crazy!

Any help or suggestions would be very gratefully received!

Thanks
Tom

This problem crops up from time to time and is because the seam is opening slightly on heating, so that the join is porous.

1. Anneal the ring before soldering, so that it is less springy.
2. Treat it more like silver, by starting to heat far from the join as possible and don't home in on the solder until the shank is upto temperature.
3. If all else fails use binding wire too to keep the join closed.

Most likely you are using an unfamiliar torch, or a heavier shank than usual to suddenly bring this on. Dennis.

Walk away from it and come back to it tomorrow.
It'll be fine then.
It's just the soldering gods toying with you :)

My suggestion (based on experience!) is that the joint looks as if it has flowed but in fact hasn't. so the solder is tacking the joint but opens when you put it on the mandrel. It may be that over time you aren't as fussy about the two sides actually being in good contact, or one side of the the joint is just that little bit cooler than the other so the solder melts onto one side only and tacks the joint but does not achieve a full flow. The only remedy is to start from basics. Saw the joint clean and be really fussy about making sure you have good contact with clean metal on both sides. Then ensure a good flow with both sides equally heated so there is evidence of flow on both sides.

Thank you all for your suggestions and help. I took it all on board and have had success. However, I'm not completely sure what it was that made the difference. I think at least part of the problem might have been a porosity in the joint, or an overcooking of the solder that then affected the sides of the joint and prevented my further attempts. Anyway, thank you all.

Tom

Dear Tom,
Thank you for your feedback. Please do join in from time to time, so that we can benefit from your knowledge. Regards, Dennis