Sil-Phos Identification

[jmpharrington]

A few questions before I start the next round of experiments.
Documentation forf Sil-Fos states flux is NOT required. My boiler appears to have been assembled with flux, based on observed staining and oxidation. See attached picture.

What would the flux of choice have been say 50 years ago?
Second, will a propane plumbers torch give me enough heat to braze a few pieces of 1/2” pipe?
Thanks
Jimmy

[Bill Shields]

You are going to be absolutely sure the area being plated is totally clean. Considering the nature of joints assembled with this stuff...the biggest challenge.

Sulfuric acid baths do not alwats get the surfaces totally clean without a lot of mechanical cleaning. I have experimented with acid followed by glass beads.. then acid...

[Bill Shields]

The end of your boiler may have been assembled with something else.

Try to scratch it with a knife.. is it soft like lead solder?

I have seen boilers assembled with all sorts of solder mixes.

Plumbers torch for 1/2 copper piping and sil phos? Sure why not..if it is an acetylene torch and not propane.

You can do it with straight propane but it takes quite a while...

[jmpharrington]

Definitely not soft like plumbing or electrical solder. I shaved a lumpy piece off with a chisel and hammer, and subjected it to a 100W soldering gun. Zero effect, other than charring the workbench under it.

I am a ways off and several rounds of experiments from attempting to plate the boiler...
Plan on cleaning with a rotary tool with abrasive buffing wheel, soda blast, and acid. Rinse and repeat as necessary.

[Bill Shields]

So it is probably a variety of silver solder done with flux.

If so then that area does not benefit from plating

[Bill Shields]

be aware that if it is 'silver solder' from the described time period that is most likely contains cadmium..

if you are using a rotary tool..you do not want to be breathing the dust.

I am not totally sure that the risk of cadmium poisoning can be induced by dust...but never hurts to be safer rather than sorry.

[LVRR2095]

Why are you planning to do anything to the boiler? It appears to be silver solder and neatly done. If the boiler doesn’t leak I wouldn’t worry about it and just run it and have fun. If fifty or more years down the road it starts to leak...that’s is when I would consider another boiler. What I see in the picture looks like very nice work and should serve you just fine for many years to come.

Keith Taylor

[Bill Shields]

Never heard that recommendation before..