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Robb S3

DIY refractory surface for brazing/soldering

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Hi all,

 

I've been reading these forums for a couple days now trying to find a solution to my problem but I can't seem to find a straight answer. I'm on a tight budget looking for cheap DIY solution for a heat resistant surface for brazing/soldering (not sure which is the correct term) small copper and brass pieces. I know there are commercial solutions out there like solderite boards (not sure what the material is technically called), but they tend to be pretty expensive (~$35 for a 12"x12" piece). I'd like my protective layer to be somewhat larger than that -- in the ballpark of 24"x24" inches.

I plan on using a charcoal or honeycomb block to place my project pieces on directly, but I'd like another larger protective layer underneath (and probably also behind) the charcoal block to prevent heat damage to the underlying bench surface. I originally was going to use sand/POP but I quickly discovered that was a big no-no after stumbling upon IFI.

I'll be using a basic propane torch (the kind you can buy at home depot for $15-$20 with a tank included) to do my heating, and again, the work piece will be sitting on a charcoal block so that will be receiving the heat directly. I'm assuming the underlying protective surface will need to reflect or re-radiate the heat, but I don't know if that's only the case if the work piece is on said surface directly. Since it won't be (in my case), would it be sufficient to simply use a heat resistant surface that may *absorb* and draw heat away as opposed to reflecting it? In that case I would think a simple piece of mild steel or even the aforementioned sand/pop mixture might work since it wouldn't be subjected to the torch directly and therefore wouldn't erode away.

I've seen that kaowool is a popular component in DIY forge building, so I'd also think I could just put a layer of that down underneath the charcoal block, but then I ran into the problem of the fibers being thrown into the air and ending up in my lungs, which I definitely don't want. Further, while it's not *that* expensive, I feel like I can get away with an even cheaper solution considering I won't be working on the kaowool directly. Not to mention adding a rigidizer into the equation to counter the problem of the fibers will push me past the edge of my already small budget.

Apologies if this isn't the right subforum to post this question in. And thanks in advance for any advice.

Rob

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If it will be on a block anyway why not a box of just dirt or plain clay kitty litter?

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That would be great if it could be that simple, but I honestly didn't know. I guess my question was how much heat might "overflow" from the block and hit the surrounding surface. If it would be little enough that dirt/litter would do the job, then yes that would definitely be the cheapest solution. What are the repercussions if too much heat hits the surrounding area?

Thanks for the quick reply by the way.

Would sand/pop be kosher in my case simply to give me the ability to form the protective layer into a solid surface (mostly for the backing which would have to stand vertically).

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It sounds like you are trying to solder. You haven’t said what you are trying to solder, or the exact torch you’re planning to use, but it sounds like you’re going to create a large heat sink with what you plan on laying it on.  If the pieces are large enough I would make a table from expanded metal to lay them on and get a torch with a small tip to direct the heat where you need it 

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Bentonite kitty litter would be ok for a HUGE amount of heat overflow, we used to use it as part of our recipe to make bloomery walls to smelt iron from ore.  Dirt would depend on your dirt.  Out here I use the stuff used for adobe to build forges to forge weld in---2300 degF & up.

The loose surface will also allow you to form it to hold the blocks you are actually soldering it on.  Why not try it and see if it will do what you need it to? Just remember that it needs to be DRY and kept DRY!

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1 minute ago, ThomasPowers said:

The loose surface will also allow you to form it to hold the blocks you are actually soldering it on.

Ah that's a great point I didn't consider and something that would definitely be useful.

Looks like I will go ahead and test it out -- my main concern was with safety and price, but litter is obviously cheap enough where the latter isn't an issue. So as long as there aren't any safety concerns then it sounds like the way to go.

Thank you for your amazingly fast replies. This is a great forum that I'm disappointed in myself for not finding a long time ago..

Rob

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Got any friends with cats that might be willing to give you a coffee can full of CHEAP, just clay, litter to try with a torch and see how it acts? (Preferably unused...)

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I do.. I have two cats, myself, ha! When I encountered the info about kaowool and lung cancer I was reluctant to test on anything that might throw particulates into the air, but it sounds like that's not so much an issue here, and I already have a P100 dust mask...  

7 minutes ago, ThomasPowers said:

(Preferably unused...)

Lol

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What is soldering?

Soldering is define as a group of joining processes where coalescence is produced by heating to a suitable temperature and by using a filler metal having a melting point not exceeding 8000 F(4270C) and below the melting point of the base metals. The filler metal is usually distributed between the properly fitted surfaces of the joint by capillary action. The traditional tool for soldering is the soldering iron with a copper tip (it has high thermal conductivity) which may be heated electrically or by oil, coke or o gas flame.

 

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Actually the traditional tool was a charcoal brazier and a goosewing to fan it with---Theophilus describes it in Divers arts written in 1120 A.D.

 

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On 2/9/2020 at 9:23 AM, Ahaha said:

What is soldering?

I am not sure what your point is , but so far,  your posts are repeats of other peoples postings, and  not very accurate either. I dont know who you are trying to impress but it isnt working

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As regards the OP, in your shoes I would just use hard firebricks laid in place on your bench surface.  Probably slightly more expensive than kitty litter, but certainly more stable.  If you surf Craigslist you can sometimes come up with used ones from a old pizza oven or furnace.  Old school (no, not as old as Thomas's citation) used to be a piece of 1/4" thick transite, but that is mostly asbestos, so we can't advocate it any longer.

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