drop thru is not a problem when soldering because of the much lower temperature than when welding. No problem with adhesion when using flux. Material is tin with some additives, which can be lead. If so, use mask.

Yes, you need bare, clean metal.

No, not same solder as plumbers use. That is for copper. But it might work. The brushed stuff is flux. A mixture of acid and tin used to prime the steel. Important to get the solder to stick to steel. More details here: www.inditravel.org/en/body-solder/

Same here. Was easier than I thought. Remember to clean well after solderling, else rust will Come.

I think Caswell talks about this. Nickel first, then copper, then solder, then more copper and finally chrome. I think...

Have You the ability? Show your work please

I was thinking the same... light heat might weld..

It is better, yes. But in this case it was rather rusty so welding would only burn holes. And it would be difficult to fabric new pieces to weld in.

You should cover it with a primer first

Ever heard if a Lead Sled. .i think vw/Porsche used lead for seamless seams back when.

Like here, steel is sandblasted, tinned and painted with epoxy. Close to zero chance for new rust from front side within 30 years. BUT, rear side is a cavity, not sandblasted, and if it is gonna rust it is from this side. To prevent that, cavity is sprayed with a creeping non hardening rust inhibitor (Fluid Film) and sealed.

Define won't last? WHERE I have done it it lasts about five times longer than bondo :) But mig is easier.

You can get lead-free body solder. I use it all the time because you can grind it just like a plastic filler. Creates less dust and is easier to paint over.

Well, I completely disagree. When I restored a Classic car, there was absolutely nothing wrong with the metal. I hot-soldered the bottoms of the Trunk, Hood and both Doors, around the Windscreen (with glass removed) and then sanded to smooth. Then the car went for new 2-Pak Paint. Really, I did this where water forms. I still own the same classic car. Not a trace of rust on anywhere that has received this treatment. That was nineteen (19) years ago. This process stops rust before it begins........

That sounds fine. Old methods work. Problem with bondo is that it sucks water and rusts. Must be covered with epoxy to avoid rust.

Yup

I agree welding is better, but soldering can be a lot easier when the metal is very corroded and thin, as it was in this example. Steel and tin/lead is rather close in galvanic potential so there is not a big chance of galvanic corrosion. You also need an electrolyte (water/salt) to start galvanic corrosion, so if you cover with a dense primer like epoxy the chances are small.

There is a place for everything. I have a 1959 jaguar, ,,factory LEAD on fenders NO ISSUES.

@@ironworkerfxr7105 "factory finished" is the critical factor as almost all production cars until the late 70s used lead as a filler - Leading over oxidised steel(ie chemicaly active) is worse than using cataloy, which is metalurgically inert. The critical factor is always to remove Tin Worm and start afresh whenever possible, as corrosion is a sign of moisture ingress, either wicking between seams, or condensates within cavities. Leading(regardless of alloy) will not adhere to oxidised steel, so in effect you are creating a boundary layer between filler and parent metals that induces moisture absorbtion via capillary action(and associated corrosion), as well as by galvanic reaction(without even mentioning the chemically active fluxes). In effect it looks good for a while, just like spreading cataloy over corroded parts - we've all seen those tell tale signs of bodged repairs on otherwise great looking vehicles, and know in our head that the tell tale is only the tip of the iceberg re: Tin Worm! I offer this advise based on decades of building and rebuilding classic British cars, and heavy plant(both renowned for corrosion, even from the factory), as I'd hate peeps to fall into the trap of bodging with lead in the misconception of it's superiority to bodging with cataloy - this is in NO way besmirching the YT poster's content, but just helpful advice. :)

The tin in the solder works like a sacrificial anode to reduce rust until it has corroded away. It's why galvanized steel (steel electroplated with a very thin layer of tin) takes so much longer than steel to rust :)

I wondered that myself. A pitted/thinned section of sheet metal I can see leading being a viable option, but not once holes have fully penetrated the sheet metal.

Because of location, and being that tight, You would make a bigger mess cutting an welding, this is Spot-On! Well done!

It's not easy to weld rusty materials. Sometimes the leftover steel just burns and you end up with more and more holes to fill. Tin soldering is a very gentle method to repair thin and rusty panels

Much better than welding... Too thin, will blow through, curved so you would need to spend a lot of time forming the patch piece. This is so much faster and easier.

I don't think that's true, for the solder to stick the acid is removing the rust. The lead should protect the steel. Often I see people sanding to bare metal removing the e-coat on cars and absolutely starting a massive rust problem. Maybe your an expert and treat the metal and treat it properly to prevent rust.

They used to use something called terne metal for roofing. Lasted over 90 years if the paint was maintained. When you tin steel, you are creating terne metal.

It can be a problem if you dont clean away flux after soldering. It is an acid and has to be neutralized.

Wouldn't you need the flame for the flux tin to adhere to the metal? Just asking I have a big iron never tried this but have body spoiler bolt holes that need filling without too much heat was going to solder then weld them

@@zdravkomomci7570 There is a huge difference between 'Pin Holes' and 'Bolt Holes'! I am guessing that your Bolt Holes would be at least 10mm in diameter. This is more suited to the job of a MIG Welder, where you could make 'blanks' of similar gauge metal / hole diameter, and then weld them into position. Hope that this helps you.

I Restore shot out Rifle Barrels by drilling out and reaming for a Rifled Tube which I Solder in. Found that a Very Large Electric Soldering Iron is perfect for Thinning the Outside of the Liner. Biggest problem I had while using a Torch was getting the metal up to Temp but not Overheating it. With the Iron I can just Walk the Puddle down the Tube.

@@NRDavis-wl8vn Glad that you have found the use of a large Solder Iron to give good results. I swear that I did not know that you could renovate a Rifle Barrel in such a way!

old school, and far better overall.