Silver Solder beading up
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  1. #1
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    Default Silver Solder beading up

    I'm trying to fill a small void in what I am told is carbon steel (a small part). I have Weldcote 56 silver solder wire and white paste flux. I sloshed the part around in acetone to clean it up, but the void was pretty clean to begin with.

    I heated the part (oxy-acetylene), dipped the silver solder wire in the flux, and smeared it on the part, continuing to add heat. After the part was red hot, I tried to apply the silver solder wire, but it just beaded up and ran off the part.

    Any tips on how to get the silver solder to fill the void and stick?

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    I use StaySilv flux. This is how I do it.

    Bead blast the area to be filled in or grind/file/mill so the metal in the void is clean and not burned. Then apply flux to the void generously. Only then heat the part until the paste flux becomes clear like water. At that point, dip the silver braze into the flux can and apply to the void. It should begin to melt but if not keep heating the part and the silver braze till it does.

    The silver braze will follow the heat. so you will have to get used to keeping the part hot while working the silver braze with the torch. I work mostly with 45% but 56% will work. It just takes a bit more heat. They do make a higher-temp black flux that may work better for 56% if you still have no success. Hope this helps.

    Best Regards,
    Bob

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    Thanks for the tips, Bob. I'll go ahead and clean it up again, including bead blasting this time. Also, next time, I'll apply the flux to the part cool.

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    Chances are that red hot is too hot. Use the paste flux to determine when it is hot enough as Bob posted above. Also make sure to heat the part evenly, as in from the bottom if it is a small part. This will keep it from losing heat too fast and allow the silver to flow.

    Teryk

    Sent from my XT1710-02 using Tapatalk

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    Cleanliness is the secret of silver brazing. If water beads up on the part, its not clean enough. I use spray on oven cleaner to remove all oils. The flux needs to be applied to the cold part. Something has to protect the clean surface from oxidizing while you bring the part up to brazing temperature.

    A part cleaned with oven cleaner wants to rust. As soon as you are finished brazing, get some oil back on the part.

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    The part, even when red hot, won't melt the silver solder wire when I touch it to the part. That's surprising to me. What am I missing there? Based on a color chart I looked up, my friend and I both agreed the part was probably 1500-1600 F.

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    Heat transfer.

    If the flux is liquid and clear and hasn't been cooked yet, the metal is ready to accept the silver. Dip the filler in the flux and hold it against the part. Gently melt the filler with the flame so that it goes liquid and is sucked onto the part.

    Sent from my XT1710-02 using Tapatalk

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    Quote Originally Posted by birdus View Post
    Based on a color chart I looked up, my friend and I both agreed the part was probably 1500-1600 F.
    Is this the filler you are using?

    https://weldcotemetals.com/dataFiles...Silver56CF.pdf

    Temperature range is 1200-1400 F. Better to stay at the low end which is why you use the flux to tell the temperature, not the color of the metal.



    Sent from my XT1710-02 using Tapatalk

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    First dumb question - have you tried a magnet on the material? It could be carbon steel, or it could be something else. The oxide layer that SS makes gives it more resistance to silver soldering/brazing.

    2nd (not so) dumb question - have you access to the brown/black stuff? From McMaster it's this number: 7645A41 While nominally for nickels and such, I prefer it for all the silver work I do. It seems to hang in better at higher temps, giving a little more leeway when freehand torching the part.

    The proper name (at least for this brand) is Stay-Silv Black Brazing Flux (https://www.harrisproductsgroup.com/...-flux-101.aspx for reference).

    Last, coating the solder in flux is good, but try to not heat the solder directly, I always want the part to do all the melting. If it can't, you can tweak it a bit, but minimize direct flame exposure.

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    Quote Originally Posted by Milland View Post
    First dumb question - have you tried a magnet on the material? It could be carbon steel, or it could be something else. The oxide layer that SS makes gives it more resistance to silver soldering/brazing.
    Dammit! It's not magnetic. The part is a beaver tail grip safety for a 1911 made by Caspian. They told me "they are carbon steel." So, I'll assume that's why the silver solder was beading up.

    So, I just e-mailed them and asked if I should use 308 or 410 filler with my oxy-acetylene torch to fill the small void, as I have both. We'll see what they say and how that goes. My understanding is that the flame will need to be carbeurizing.

    Learning a lot! Thank you guys for your patient help!!!

    Jay

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    Quote Originally Posted by mTeryk View Post
    Is this the filler you are using?

    https://weldcotemetals.com/dataFiles...Silver56CF.pdf

    Temperature range is 1200-1400 F. Better to stay at the low end which is why you use the flux to tell the temperature, not the color of the metal.
    Yes. That is what I have. However, it would now appear that my part is stainless steel, so I believe I'll have to take a different approach.

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    Sometimes it's hard to feed the silver solder, especially with small parts that want to get pushed around. I've had good luck cutting off a short piece of the silver solder then hammer it into a strip or oval or another appropriate shape depending on the application. Then clean everything, flux everything, and set the piece of silver solder in the flux in the area to be soldered. Then just start heating the whole thing up. First the flux will melt, flow, and go clear. Then the silver solder will melt and flow. Then take the heat off and done. Can be a lot easier than trying to predict the correct temperature and feed the solder in.

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    Quote Originally Posted by birdus View Post
    Yes. That is what I have. However, it would now appear that my part is stainless steel, so I believe I'll have to take a different approach.
    I believe most if not all stainless can be silver soldered. I've silver soldered at least 304,308 and 17-4. We did get some stainless cable once that had some sort of coating that kept the silver from wetting out. If nothing else works perhaps that is your issue.

    One thing, another poster suggested sand blasting. I was always of the opinion that sand blasting made silver soldering more difficult. I would always hit sandblasted surfaces with Scotch Brite prior to silver soldering as it seemed to flow better that way.

    Sent from my XT1710-02 using Tapatalk

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    Yes as far as I know all stainless can be soldered.

    I myself would TIG weld it, if possible.

    I have soldered 300 series stainless steel a few times quite some time ago. Kind of finicky at first as I recall, but once you get the hang of it it's fairly easy. I used the stuff below to solder 304 and 316 to each other on some really hard to reach, tiny, thin stuff. Also have used it to solder s.s. to brass and copper.

    When you thought the part was carbon steel why didn't you gas weld it if your now going to gas weld the stainless?

    Here's the stuff I used to solder stainless, it's a liquid flux: LA CO N-3 ALL PURPOSE FLUX.

    Clean your parts real good with acetone, you have to keep the joint wet, this stuff is a liquid and will burn away, don't burn it. If it starts turning black your getting to hot. Get your part up to temp first and then start dripping or whiping it on with a cotton ball/swab.

    Good luck 👍

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    As mentioned already, cut a piece of solder from your wire and place it with the flux on the spot to fill. Apply heat around the repair area and not directly on it. When the part reaches the melting temp of the solder it should flow quite instantly. Use plenty of flux as some stainless can develop an oxide layer on the surface and the solder will wet to that giving the appearance of a good solid repair but will flake off the parent metal with some force. Oil contaminated parts are not as bad as oxidized stuff - most oil will burn off. Jewelers will typically cut small pieces of gold or silver solder (called pallions - or French for pillow) and place them in the appropriate area for joining. A soldering pick or pointed wire is used to move them around in the bubbling flux as needed.

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    Quote Originally Posted by azmachining View Post
    When you thought the part was carbon steel why didn't you gas weld it if your now going to gas weld the stainless?
    I guess I just thought silver soldering would be safest, since the part is small.

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    List of brazing alloys - Wikipedia

    many/most of the brazing alloys for stainless steel are on the order of 20% zinc. i forget which alloy i used but it was a rod designed for dissimilar metals, i think it was silvaloy 505. it had zero issues wetting a stainless steel heat exchanger from a residential natural gas on demand hot water heater, using Harris white flux.

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    Caspian told me point blank about the beaver tail grip safety "they are carbon steel." Previously, I had thought it was titanium (then possibly stainless). Long story short, they just told me they DID make some grip safeties and main spring housings of titanium.

    When I grind on it, the sparks are very white, so I believe it is titanium. Sorry for the rabbit trail, but I learned a lot. I think we now know why the attempt at silver soldering was such an abysmal failure.


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