Torch for Silver Soldering Copper Boiler

[Builder01]

Great tips Bill, Thanks! My torch kit is ordered and I am waiting it's arrival.

David

[xo18thfa]

Good news David. You will be pleased with that torch. It's all practice. IMHO "reading" the flux is important. The flux goes through a number of stages as it heats up. Just before the solder flows the flux is mostly clear and bubbles. You will see bright shiny metal underneath as the bubbles pop. Then solder melts and sucks right into the joint. Works every time.

You'll need a "pickle bath" to clean off the residue flux. There are several, I use citric acid. Just used to it, plus I have a lot of it.

Looking forward to seeing some of your work.

vr Bob

[Builder01]

Thanks Bob,

I have been deciding between sulphuric acid and citric acid for a pickling solution. It seems the sulphuric is so corrosive that it is not recommended that you keep it in your shop. Currently, for the small silver solder jobs I have done so far, I have used vinegar and water for a pickle solution but, it take a really long time to do the job . Is the citric acid as aggressive as the sulphuric? Where would I get citric and what ratio of water to acid is effective for citric?

[Bill Shields]

Not recommended by whom? some 'expert'?

There are many dangerous things in a shop.

10% sulfuric acid is what I consider one of the least hazardous....far below the drill press (for example).

put it in a bucket with a lid on it. (acid not drill press)

If you have kids around, that is another story, but otherwise it is no worse than easy-off oven cleaner, acetone, bleach or other items.

[Builder01]

Hi Bill,

My concern is about the fumes causing rust. My shop is pretty dry and there is almost no rust on anything. I was absolutely planning on a lid for whatever my pickle solution is. My only concern is about things near the pickle tank getting rusty. I was going to store the dip outside and keep it out of the shop altogether. Other than that, I am not worried about any other danger. Perhaps citric acid fumes will react with ferrous metals the same as sulphuric, and it really makes no difference, I have no experience with acid dips for cleaning. I am curious about the pros and cons of citric versus sulphuric.

[Bill Shields]

I have not experienced this rusting problem...although I have to admit that the acid bucket is over in the corner near the wash-up sink since things tend to go from one to the other.

I keep machining in one area, welding / grinding in another, washing / acid dipping in a 3rd near the sink & drain and bead blasting away from them all.

Generally I like to put parts in the acid while they are still warm so that things work faster.

Sometimes I will wash to get rid of the flux & major crud, warm slightly with the torch then acid dunk to final clean.

NO...I am not silly enough to toss HOT parts directly into the acid. Anyone dumb enough to do that should find another hobby before they seriously hurt themselves.

[xo18thfa]

Citric acid comes in powder form. I got it from McMaster-Carr, 5 lb tub will last a long time. I hear you can get it at most health food stores, but don't know for sure. Mix it in water until saturation. Citric acid is non-toxic and has no fumes. Sulfuric acid is dangerous stuff. It eats steel, whereas citric does not. Citric works quickly, pickled parts cleans up easily. It's good stuff.

[Builder01]

Hi Bob,

Thanks, yes, in fact I already found it on McMaster-Carr. Any suggestions for ratio of water to powder?

David

[xo18thfa]

Hi David. Just add the citric acid powder to water and stir until no more powder disolves. When the powder just starts to settle out, you are in business.

[Builder01]

Hi Bob,

Okay, makes sense. Thank you!

David

[Builder01]

My Sievert torch kit arrived today! WooHoo!!

Many thanks to Bill, Bob and others for getting me down the right path.

Included in the kit are the torch head, handle, 20' of hose, regulator, spark lighter and a clamp/stand for the torch. The regulator fits a standard propane cylinder/tank like the type used on a outdoor grill. Looks like a heck of a torch, should be perfect for what I need.

Won't be able to try it out until next week. I'll be at the club track for show and tell with my chassis running on air!

Thanks again,
David

[Bill Shields]

get a longer pipe between the head and handle...you will need it!

these suckers put out a huge flame.

keep the pressure up...understand 4 bar?...about 60 psi....I actually put a pressure gauge on mine so that I could see the pressure at the hose with the torch on full blast...