Solder question

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Re: Solder question

Post by jscarmozza » Sat Dec 30, 2017 9:40 am

I'm going to have to try and look up the stock number on the silver solder that I got from McMaster Carr, I'm not sure if it contains cadmium. What's the difference and or benefit between white and black flux, I've often wondered? All the McMaster catalog says is the black contains boron and is good to 1700 degrees, white is good to 1600 degrees.

I'm self taught, so if something works for me, that's the way I do it from then on. I use an O/A torch with the flame just off feather, I found that if I leave a feather, I wind up soothing the part. I also use the Henrob 2000 torch, this torch gives a very hot concentrated flame and may not be the best choice for silver soldering, as it sounds like I should be using a torch with a broarder flame. Thanks for the input, John

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Re: Solder question

Post by Fender » Sat Dec 30, 2017 11:28 am

I prefer the white flux, because it quickly becomes transparent when hot, so it is easy to see the solder run into the joint. If you use oxy-acetylene it is very easy to overheat the joint. Keep the flame moving, so you’re not hitting the same spot for more than a second or two at a time. If using non-cad solder, you may need to use a higher silver content to get the same degree of fluidity.
Another thing to consider would be to use stainless tubing for steam and water lines, rather than copper. I think that ss is easier to braze b/c it doesn’t conduct heat away as fast. Also, it is mechanically stronger than copper and looks better, since straight runs stay straight-looking, while soft copper tends to get wavy from bumps and tugs over time.
Dan Watson

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