# 15 and 57 % silver brazing hvac rods or wishful thinking?



## jeepjones85 (Sep 22, 2012)

Hello everyone I'm new to this forum yall have some really good info here.
Anyway the whole reason i joined was to find out if what Iv saved up all
These years in the HVAC trade was worth keeping lol 
I have a whole pile of left over brazing rods some of them are non flux coated
and some are coated. The non coated ones I believe are 15% silver and the coated
ones are 57% silver.
Iv got two 5gal buckets all most full of both.
Is this worth saving to scrap and smelt down into bars?
Or am i just wasting my time on wishful thinking.


----------



## etack (Sep 22, 2012)

If your nitric is cheap enough they are worth it.

I sent you a PM

Eric


----------



## goldsilverpro (Sep 22, 2012)

In my mind, there are basically 2 types of silver brazing alloy - that that contains cadmium and that that doesn't. Due to the great possibility of cadmium being present, melting could be very hazardous to your health and it could kill you. The fumes are quite toxic.

About the safest way to recover the silver would be to dissolve it in 50/50 nitric acid, filter it, and then cement the silver out with copper tubing or bus bar. This is a recovery process and, if done right, the silver purity will be about 99%. For higher purity, a silver cell is required. The details on how to do all of this has been given many times on this forum. The same method is used for silver contact points and sterling silver. It will take about 3.7ml of 67-70% nitric (diluted 50/50 to 7.4ml with distilled water) to dissolve a gram of the 15% material. For the 57% material, it would take about 2.5 ml/gram (diluted to 5ml).

It would be best to remove (hammer?) as much of the coating as possible before using the acid. The reaction of the coating with the acid could cause problems. Also, the coating removal would allow you to get a good weight of the material so the amount of acid needed could be more easily calculated.

The only problem I see would be the tin. Most all of this material contains some tin but, according to the manufacturers charts, it is fairly low - most I saw was from 2-5%. In nitric, the tin is converted to metastannic acid, a sludgy material that is difficult to filter.

To do this, you will need fume control, preferably a fume hood. The red-brown fumes produced are very visible (to the authorities) and toxic. You might be better off selling the material.

The book I sell has a fairly extensive section on processing silver contact points. The only difference in running this and your brazing alloy is the tin, which is mainly a filtering problem.


----------



## jeepjones85 (Sep 25, 2012)

Hey thanks for the reply I'll definitely look into this ! Sorry I didn't respond quicker i went out of town on job. 
And iv already hammered off the flux on the 56% rods im going to try the acid trick first.
I'm not really sure of the process or exactly what happens after the acid bath though.


----------



## Palladium (Sep 25, 2012)

Study before you just drop them in acid and get into trouble. What you have can be fairly easy to do, but not without the proper safety and knowledge of the process.


----------



## alanmx6 (Aug 27, 2014)

so the silver is in the metal center rod and not in the outer flux coating?


----------



## Lou (Aug 28, 2014)

Do you have a couple hundred ounces? Might just be easier to sell to a refiner. This isn't the easy scrap to learn on--the tin makes it a royal pain in the behind.


----------

