Rehydrating paste solder

So, I got this large amount of easy paste silver solder in a jar. Been using it for years. Like 20-30 years :slight_smile: I keep it tightly screwed down (covered), but … its getting a bit stiff these days … like everything else on my old body. I work mostly with Argentium these days … so … it’s a lifetime supply. I almost never do standard sterling … but I do have a “stash” of it I use sometimes. Argentium … that’s a love/hate relationship … lol. I’d rather do 18K or better - yet another story.

Anyway … its getting dry. Any ideas on how to rehydrate it?? I’ve pondered putting a few ccs of water in it and shutting it tight for a bit. I almost ever use it. Mixing it with a bit of water before use? Ideas? Not going to recycle it … I have quite a bit still in the jar and want to continue using till it’s someone else’s problem.

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I have thinned paste solder with mineral spirits. It seems to work. To a trial run before you do all of it…Rob


Since solder paste has flux in it, could you not simply add some liquid flux? Like a thin layer on the surface, put the lid on, and let it absorb?


Hi Brent, almost all of what I saw thirty years ago was water-based. Hilderbrandt may have used something in their tube solder. As benchtop induction heaters are commonplace these days I would start from there. With your jar almost floating in a very large induction pot, full of water. Add a little water to your flux and then warm the pot of water to finger warmth for half an hour plus. The problem will arise if the water temperature in the pot gets a little too warm then the silver solder may well expand and tears all around.

I and my dad always used distilled water. Break off a small piece and try it. If you’re in a hurry crunch it like a mortar and pestle. Keeping it clean is the important thing.
Remember distilled water!