Pickling solution for silver soldering?

[Inflight]

Hi all,

Kozo Hiraoka recommends a weak solution of 10% sulfuric acid and water for pickling silver soldered brass joints. Today, I didn't have any sulfuric acid on hand, so I tried fresh squeezed lemon juice. :nuts:

Can someone explain the purpose of pickling and what is technically required for proper silver soldering?

 

[12bolts]

Hi Inflight,
Talking again....
Pickling is basically the use of acids to clean scale/oxidation/impurities from the surface of materials. It is convenient to use after welding/brazing because it gets into all the nooks and crannies and cleans everything up nicely. You cant beat abrasives for cleanliness and fluxing is basically doing the job of a pickle paste beforehand anyway.
As far as the process of joining metals, cleanliness, cleanliness, cleanliness!

Cheers Phil

 

[mike44]

Most acids will clean the metal. I use household vinegar. Sulfuric acid works quickly. Vinegar or citrus acid also works but takes longer.
I rather work slower and safer, sulfuric acid needs proper precautions in use.
mike

 

[Cobra]

I have always used sulfamic. Less likelihood of damage and easy to store in a dry powder.

 

[RJSakowski]

Many fluxes for silver soldering contain fluorides. Chloride based fluxes tend to form an insoluble coating on silver. If you are just prepping the brass, you can use hydrochloric acid (muriatic acid) to clean the brass effectively but you should rinse it thoroughly. Vinegar is dilute acetic acid, usually around 5%. Lemon juice is dilute citric acid. Neither of them are particularly effective at rapid corrosion removal. The hydrochloric acid will be virtually instantaneous. Sulfuric acid (battery acid will also work as will phosphoric acid.

Many people object to hydrochloric acid use because of the fumes which are irritating and will cause surface rusting on tools and machines. I use it regularly, keeping the solution tightly capped when not using it and using in a vented area. I have been doing this for more than fifty years with no issues to speak of.

 

[middle.road]

Many fluxes for silver soldering contain fluorides. Chloride based fluxes tend to form an insoluble coating on silver. If you are just prepping the brass, you can use hydrochloric acid (muriatic acid) to clean the brass effectively but you should rinse it thoroughly. Vinegar is dilute acetic acid, usually around 5%. Lemon juice is dilute citric acid. Neither of them are particularly effective at rapid corrosion removal. The hydrochloric acid will be virtually instantaneous. Sulfuric acid (battery acid will also work as will phosphoric acid.

Many people object to hydrochloric acid use because of the fumes which are irritating and will cause surface rusting on tools and machines. I use it regularly, keeping the solution tightly capped when not using it and using in a vented area. I have been doing this for more than fifty years with no issues to speak of.

Mine are stashed out in the tractor shed and that's where I use them. Well ventilated and if something goes south, nothing much will be damaged.
All of the few 'acids' that I have are out there, in different areas on the floor so that they don't 'intermingle'.

 

[wudwlkr]

While not as fast as hydrochloric acid I use sodium bisulfate. Often sold as Ph adjuster for swimming pools. 1/4 cup of sodium bisulfate to 2 qts of water seems to work well. If the solution can be heated the cleaning action will be sped up. No odors and no fumes to rust other nearby metal objects.

 

[aliva]

I usually buff the parts first, then acetone and then the flux coated silver solder rod. No issues so far.