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brian Rupnow
11-06-2009, 02:56 PM
I have just silver soldered something, and it is knurled. The melted solder flux has ran onto the knurled section. I can't bash it out, because it will spoil the look of the knurl. Is there any readily available chemical (helpfully in my kitchen) that will dissolve unwanted solder flux after it has been melted, then hardened again"

brian Rupnow
11-06-2009, 03:07 PM
Duh~!!! May have just answered my own question.---A 5 minute soak in water and a wire brush seems to have gotten rid of it.

Steve Steven
11-06-2009, 03:09 PM
I have just silver soldered something, and it is knurled. The melted solder flux has ran onto the knurled section. I can't bash it out, because it will spoil the look of the knurl. Is there any readily available chemical (helpfully in my kitchen) that will dissolve unwanted solder flux after it has been melted, then hardened again"
Brian,
Try HOT soapy water. When we silver solder piping in the shipyard, we use a hot water solution to clean out the piping to remove remaining flux.

Steve

Mcgyver
11-06-2009, 03:17 PM
10% sulpheric acid is what i use, kept in a sealable plastic pail and used outdoors.

I'm surprise hot water worked, what flux was it?

brian Rupnow
11-06-2009, 03:19 PM
10% sulpheric acid is what i use, kept in a sealable plastic pail and used outdoors.

I'm surprise hot water worked, what flux was it?

Damned if I know.---Gooey white stuff with water as a base. After being melted it chrystalized on the parts.---I'm not sure if the water did much, or if it was my aggresive wire brushing.

ckalley
11-06-2009, 03:26 PM
Try white vinegar & warm water somewhere around 50/50 mix. Softens up the flux well. Also works great on brass & copper to remove the flux and discoloration.

Craig

Evan
11-06-2009, 04:15 PM
All you need to do is boil it.

camdigger
11-06-2009, 04:39 PM
Damned if I know.---Gooey white stuff with water as a base. After being melted it chrystalized on the parts.---I'm not sure if the water did much, or if it was my aggresive wire brushing.

Some white fluxes are rumored to be primarily Borax. A salt of Boric acid, available as a household cleaner. 20 Mule Team Borax was a brand my Mom used years ago. Had a picture of a mule train on the box.
FWIW, IIRC, it is used by some blacksmiths for a flux in forge welding too.

Direct quote from that unassailable source Wikipedia...
[edit] Flux
A mixture of borax and ammonium chloride is used as a flux when welding iron and steel. It lowers the melting point of the unwanted iron oxide (scale), allowing it to run off. Borax is also used mixed with water as a flux when soldering jewelry metals such as gold or silver. It allows the molten solder to flow evenly over the joint in question. Borax is also a good flux for 'pre-tinning' tungsten with zinc - making the tungsten soft-solderable.[2]

Forrest Addy
11-06-2009, 04:45 PM
Boil it in virgin urine. Or you can try Republican urine. Same thing.

Seriously hot water works just fine to dissolve away silver solder flux. No need to add acid or other ingredients. Give it a few minutes for the salt to re-hydrate and loosen up. Then take a wire brush to clear off the residues and smut. The silver solder salts leave the metal surface in a readily corrodible condition so be sure to remove them completely. Steel and iron especially should be passivated with hot washing soda and a stiff brush otherwise you may get a little rust bleeding through paint.

Alistair Hosie
11-06-2009, 06:08 PM
VIRGIN URINE don't get alot of that round here are you sure your not taking the pi$$ Forest:D:D:DAlistair

loose nut
11-08-2009, 09:46 AM
When your done soldering, drop the part in clean water while still hot, most flux will break up and come off easy. Don't do this with an acid "pickling" solution or you will get acid steam coming off of it.

brian Rupnow
11-08-2009, 11:11 AM
Thanks for all the replies fellows. I have a jar of pickle juice here, (I ate all the pickles). It says in the ingredients that it contains a lot of vinegar. In the interest of science I am going to silver solder something in the next 5 minutes and take a picture of the results---complete with uncleaned flux. I will post a before and after picture----After being 24 hours after submersion in the jar of juice.---Oh---I just love science experiments!!!!----Brian

Forrest Addy
11-08-2009, 11:15 AM
Damn it! Use hot water. It's in the label directions on most jars of flux under clean-up.

brian Rupnow
11-08-2009, 02:34 PM
Okay---I agree---It was a long 5 minutes. Wife showed up in my shop and suggested we go for a drive, just as I was about to light the torch. Its a beautifull sunny, warm November weekend (50 degrees F) which we get about once every 5 years here in Canada. What you see here is a piece of 1/8" mild steel rod silver soldered to a pair of brass balls. (Stole them off a brass monkey last winter.) You can see how the flux has melted, then chrystalized. Obviously, they have cooled off enough to pick them up with my bare fingers, and now they are setting in the jar of pickle juice which is setting in the background (With the French label side visible.) Forest addy---To be fair, I'll try the same experiment tomorrow with plain water.----Brian
http://i307.photobucket.com/albums/nn294/BrianRupnow/FLUXREMOVAL002.jpg

softtail
11-08-2009, 02:43 PM
Some fluxes are water soluable, some are not.

Hot water works most times. The black stuff in your picture is burnt flux... got too hot. Can very hard to remove. Try a mild hcl pickling solution like Picklex (Sp?), and mechanical means.. wire wheel, sand paper, scraper, etc.

If you do a proper job, hot water is all you need.


st

brian Rupnow
11-09-2009, 09:41 AM
So, here we are a day and a half after submersion in pickle juice.---Every bit of chrystalized flux is gone. The dark areas remaining on the brass are apparently the result of getting the brass too hot during the silver soldering process and "burning" the brass. Now I will repeat the same test using plain water.
http://i307.photobucket.com/albums/nn294/BrianRupnow/fluxremoval-2003.jpg

brian Rupnow
11-09-2009, 10:03 AM
This is the one thats going into a can of water---
http://i307.photobucket.com/albums/nn294/BrianRupnow/fluxremoval-3002.jpg

brian Rupnow
11-10-2009, 08:35 AM
This is the part after setting in a can of water overnight. Again, all the flux is gone, leaving the black crud only. I can not see any difference in the water as opposed to the pickle juice!!
http://i307.photobucket.com/albums/nn294/BrianRupnow/waterdefluxing001.jpg
http://i307.photobucket.com/albums/nn294/BrianRupnow/waterdefluxing002.jpg