Soldering questions

[HWooldridge]

One of my regular customers is a general contractor who does high end restorations. He recently gave me three old gas light housings to repair that date from WWI. These appear to be brass or bronze (I'm leaning toward the latter because the house was a mansion when it was first built and much of the other hardware has been bronze). At any rate, the pieces that form the housings are mostly flats and rounds that appear to have been soft-soldered together. I have soft-soldered wires in the past but nothing on this scale; several pieces have broken away over the years so I plan to buy some bronze/brass sheet and fab whatever is necessary but the actual soldering has me slightly worried.

I'm pondering on a few things:

(1) Should I get an aspirated acetylene turbo torch or make/buy some copper soldering irons? I used to cast a lot of bullets so I have plenty of lead in several grades from pure to 50/50 bar solder to linotype - and I have an electric melting pot that still works well for melting.
(2) What's the best flux for this type of work? I have collected acid flux and rosin tins over the years but again, my experience in this type of work is practically nil.
(3) I know that cleanliness is next to Godliness in soldering. Is sandblasting a good prep or does that yield too much tooth - i.e., should the material be smooth and not textured? My customer plans to strip any paint that I don't remove and powdercoat the assemblies after I get done with my work so perfect finishes are not important.

Any tips are appreciated...Hollis

[Dragons lair]

One of my regular customers is a general contractor who does high end restorations. He recently gave me three old gas light housings to repair that date from WWI. These appear to be brass or bronze (I'm leaning toward the latter because the house was a mansion when it was first built and much of the other hardware has been bronze). At any rate, the pieces that form the housings are mostly flats and rounds that appear to have been soft-soldered together. I have soft-soldered wires in the past but nothing on this scale; several pieces have broken away over the years so I plan to buy some bronze/brass sheet and fab whatever is necessary but the actual soldering has me slightly worried.

I'm pondering on a few things:

(1) Should I get an aspirated acetylene turbo torch or make/buy some copper soldering irons? I used to cast a lot of bullets so I have plenty of lead in several grades from pure to 50/50 bar solder to linotype - and I have an electric melting pot that still works well for melting.
(2) What's the best flux for this type of work? I have collected acid flux and rosin tins over the years but again, my experience in this type of work is practically nil.
(3) I know that cleanliness is next to Godliness in soldering. Is sandblasting a good prep or does that yield too much tooth - i.e., should the material be smooth and not textured? My customer plans to strip any paint that I don't remove and powdercoat the assemblies after I get done with my work so perfect finishes are not important.

Any tips are appreciated...Hollis

For heat your gonna want HOT but concentrated. I use a huge electric iron for that sort of stuff. Torchs spread the heat out and can/will cause the area ya just finished to melt out. Never had any luck with sandblasting was told it
leaves minute silica dust. I just use scotch brite or a wire wheel. Don't like acid flux I use the rosin(old electronics tech) Powdercoat bronze? At least advise them clear powder is available. Last piece I did was a weathervane. Arrow was 6 foot long 3 inch dia. 3 dimensional letters 12 inchs tall. Took a month and payed
$4,000
Ken.

[bigfootnampa]

I have acquired numerous old soldering irons from flea markets and antique malls/shops. I only ever buy the cheap ones that usually have enough copper to cover their price if I scrapped them. So there's how you can buy them at bargain prices. They are the preferred tools for most tinners and roofers. Personally I like them NOT! I have always used propane torches and I own some that can concentrate the heat to a degree not even approachable with ordinary sized soldering irons. For circuit board work where absolute pinpoint heating is consistently called for I do prefer a good specialized electric iron. I like to use barsolder 50/50 or unleaded. I have usually used waxy plumbers fluxes. Pretinning is very important for absolutely reliable joints in larger projects. This is done with the parts unassembled and after pretinning there is no need for flux as you are simply melting solder to solder. Use only torches that have a hose so that the flame can be maneuvered without tipping your gas bottle. Heat your metal and flux and let the metal heat the solder. The solder will follow the heat so lead it where you want it by moving the heat. It takes quite a bit of heat to melt out solder that has run and cooled so if you work along in a linear fashion you shouldn't have too much trouble about melting out your previously soldered areas. If your joints are reasonably close they will be tenaciously joined once soldered... even if the solder is remelted it will not leave the joint unless subjected to extreme heat. Thus we are able to pretin any areas that have folds or deep joints which might otherwise be difficult to solder uniformly. Use of sandpaper is quite efficient for cleaning joints and by controlling this process you can easily use uncleaned areas as resists to confine the solder flow to the areas where you want it. Roofers that have to pretin many linear feet of material will use trays of molten solder to dip edges into and for this type of tinning flux is not important. I doubt that you have enough area involved to want to set that kind of process up. Okay that's a lot to read so if you STILL have questions let me know what they are. You won't need or want acetylene. It is TOO hot even Mapp gas is usually overkill (though I do use it especially for plumbing soldering).

[BIGGUNDOCTOR]

Kinda of a shame to be painting bronze.

Brownells sells a low temp (400 degree)silver solder that you may want to consider.

I picture of the pieces would help determine if a torch, or iron would be best.

[Bentiron1946]

How thick is the metal? Is it sheet metal you're talking about here or are some of it cast? I used to do bronze casting and we would repair it one of two ways, silver solder or MIG weld it. We would silver solder things like toes, reins, ropes,etc on but sometime we would construct things out of sheet metal, 20 gage or smaller and we would use MIG on them and then chase the surface to hide the bead. This worked a lot better than trying to solder a seam and lasted longer and was stronger too.
It won't hurt to experiment on some scrap if you have it.

[HWooldridge]

Thanks for the replies. These are primarily made of thin sheet - I don't have a micrometer in front of me but would guess .020 thick. A lot of it is has been bent and folded on a brake then soldered together. A few joints are riveted but most are soldered with lead - I can't see anything that looks like silver or other material. Reckon I'll stick to my Bernzomatic propane torch and see how that works - I do have a bunch of 50/50 so will try that.

I also thought the frames looked good in the natural bronze color (and would patinate nicely) but apparently the rest of the pole and assembly is painted so that's what the customer wants.

[Norseman C.B.]

Back in my radiator repair days we used a premixed tinning soloution and an acid brush to apply it. After brushing it on the surface we used a natural gas/oxygen torch to heat the surface until the flux melted and brushed it with an acid soaked brush to spread it along the surface i/e melt brush,melt brush as needed to leave a bright layer of tinning, then lay parts together, clamp, and melt run a 60/40 lead tin solder wire in the joint this of course was done after wire brushing the parts to remove surface oxides.
And yes sand blasting is not good as it does leave silica residue behind.
(not condusive for bonding).
I might suggest that you go to your local radiator shop and offer to purchase some of this stuff and ask If the guy would let you observe the application process. Its not difficult
for a fairly dexterious person. Good luck with your project
and I hope I have shed some useable information upon you
Clifford B)

[ianinsa]

Hi Hollis,
I regularly do copper rooves on palaces in Abu Dhabi, these require large corbeled cornice shapes to the sides, we use guilders metal for this as it is 90/10copper technically this is a type of bronze and behaves much like both copper and brass. I always use propane/buthane torches the material is 0.45mm thick sheet and is a doddle to solder if you first clamp then whilst soldering use a wet sweeper cloth(chamoise)to follow up, This sets the joint and you leave in place while you do the next bit thereby solving the problem of the finished joint poping while you work on the next bit. Makita make a powerfile in 2 sizes that are great for precleaning and final clean-up. Black and Decker used to make a really cheap one too if you can still get them, if this is a once off then buy the B&D as they work well in every way exept longevity.We tend to use plumbers solder and 2mm acid cored solder wire, costs a dash more than radiator S5 sticks(wich we self cast)but you save a whack in time of soldering and clean-up ! Have loads of fun Ian _

[ThomasPowers]

If you have an old piece *don't* go with a higher temp solder than was used on the original unless you can totally isolate it.

No fun to stick your joint only to see that you *un-stuck* lots of previous joints in the doing!

Now if you have build ups to apply it can help to build up the replacement parts with a higher temp solder and then fasten them to the old stuff with a lower temp solder.