Brazing
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New User
Joined: Oct 2004
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Hi,
I'm about to do my first brazing with silfoss and have been told that I will be causing problems if i get it too hot. You mentioned silfoss melts at over 1400 degrees. this is fariegnheight? Do I have to go a bit hotter to braise? do you know how much hotter? Luckily I have a lazer thermomiter and can measur the temp easily but am rather concerned as it's a tricky joint ( a couple of them) in fixing up an old boiler. Oh yea, have been advised to use silflux as well (nasty stuff & fumes will kill you quick but aparently helps considerably)
I have also been told that the joint had to be perfectly perfectly clean right down to virgin material w/grinder, emery paper & cleaned with alcohol
Any other recommendations?
Many thanks,
I'm about to do my first brazing with silfoss and have been told that I will be causing problems if i get it too hot. You mentioned silfoss melts at over 1400 degrees. this is fariegnheight? Do I have to go a bit hotter to braise? do you know how much hotter? Luckily I have a lazer thermomiter and can measur the temp easily but am rather concerned as it's a tricky joint ( a couple of them) in fixing up an old boiler. Oh yea, have been advised to use silflux as well (nasty stuff & fumes will kill you quick but aparently helps considerably)
I have also been told that the joint had to be perfectly perfectly clean right down to virgin material w/grinder, emery paper & cleaned with alcohol
Any other recommendations?
Many thanks,
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
Silfoss is a trade name for silver solder, specifically about an alloy of about 15% silver commonly used in refrigeration and air conditioning.
Silver solders melt (flow) at temperatures ranging from 1300 to 1500 degrees (F). The melting point of copper is 1985 degrees (F), so you can see that the flow point of the brazing material is pretty close to the melting point of the material brazed in its most common application. That's probably at least part of where the dire warnings about "don't get it too hot" come from, but this may not be as much of a problem if you are brazing steel (melting point around 2500 (F)).
As with all brazing, the joints should fit up as tightly as possible and be as clean as possible. Brazing bonds through electrochemical forces, and the method is not suitable for filling up gaps between the materials joined.
Silver solders melt (flow) at temperatures ranging from 1300 to 1500 degrees (F). The melting point of copper is 1985 degrees (F), so you can see that the flow point of the brazing material is pretty close to the melting point of the material brazed in its most common application. That's probably at least part of where the dire warnings about "don't get it too hot" come from, but this may not be as much of a problem if you are brazing steel (melting point around 2500 (F)).
As with all brazing, the joints should fit up as tightly as possible and be as clean as possible. Brazing bonds through electrochemical forces, and the method is not suitable for filling up gaps between the materials joined.
Senior User
Joined: Feb 2003
Posts: 202
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From: southern Md
The silfloss I have used (Harris) varies in silver content from 0% to 15% is what I have used on copper pipe. The 15% is by far the best flowing of them all and I would suggest this for steel. It doesn't seem to matter much on copper.
Glenn
Glenn
Posting Guru
Joined: Mar 2004
Posts: 1,321
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From: MI
be sure to select the right brazing product for the job.
start here: http://www.jwharris.com/home/
also visit a local welding supply store.
start here: http://www.jwharris.com/home/
also visit a local welding supply store.
New User
Joined: Nov 2004
Posts: 2
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I have used Silphos since it was introduced in the 70's. Meant to be used on copper to copper joints. Definately not on steel. the copper needs to be heated to the point that it is almost glowing red. any hotter and you will get carbon scale buildup which will easily wipe off. best to use a rosebud tip but not a necessity. Copper does not have to be polished, just reasonably clean. No flux needed. Good luck
Last edited by dragsterdoug; Mar 12, 2005 at 09:33 PM. Reason: forgot something
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