Is sanding enough to remove galvanized coating from steel?

[zippy97]

Hey all. Working on my soldering and found the home depot down the street has pretty thin gauge (26) steel that is surpsingly cheap. But their thin gauge stuff only comes as galvanized sheet.

I've seen some cool ideas for metal garden decorations made from sheet metal. I'd like to try it out.

However I've heard heating up galvanized steel gives off very toxic fumes. I'd like to attempt annealing small pieces (maybe 2x2 inches), as well as doing some soldering on it with 50/50 tin lead.

Would elbow grease and coarse grit sand paper remove the galvanized coating well enough to make it safe to heat up with a propane torch for annealing and soldering?

I know you guys are typically safety conscious around here and I appreciate that. So please tell me how I can do this safely. Or if it's a terrible idea in general, just let me know. Thanks guys and gals.

 

[southalabama]

Acid to remove galvanized coating. Try vinegar.

Check YouTube for removing galvanized coating.

 

[Lwel9226]

You can solder directly to the galvanize without any problem, works great....
You would need to do some serious grinding to remove the galvanize... Not worth it IMHO...

LynnW

 

[The Cobbler]

use muriatic acid for soldering galvanized

 

[dogdog]

maybe do it in open area and wear some Personal safety equipment like mask / gaggle?

2"x2" and thin gauge metal... not sure.

 

[Bert_]

You can solder straight to the galvanized. If it gets hot enough yes it will give off some nasty fumes. Do it outside and it's not much of a concern.

 

[Yankeefarmer]

Since you are planning to remove the galvanizing, have you considered just working with 22 gauge which is readily available plain?

 

[lilredex]

Back in the day eavestroughing was made from galvanized steel with soldered joints. Plumber's paste is a good flux to use (or muriatic as above... Cobbler).

What do you mean by cheap 26 Ga. sheet metal? How cheap?

 

[steel 35]

use muriatic acid for soldering galvanized

This but outside it rust’s everything close, and it’s nasty but easy and effective.

 

[rlitman]

...Working on my soldering...

Soldering or welding?

Zinc solders nicely using acid based plumbers flux, so long as it's been cleaned just before soldering (just like any soldering, oxides need to be sanded off first). Steel doesn't solder nearly as easily, so if you're soldering steel, you'll want the zinc there to help.

For welding, zinc gives off toxic fumes when heated to the far higher temperatures of welding, and the safest way to deal with this is to remove the zinc down to bare metal, at least as far away from the joint as the far end of the HAZ.

 

[zippy97]

Thanks everyone, it sounds like soldering with a propane torch won't get hot enough to give off fumes. That's good to hear.

I may give muriatic acid a go in the future if I really want the coating off for some other reason like attempting to anneal it or work it while it's really hot.

 

[rlitman]

...it sounds like soldering with a propane torch won't get hot enough to give off fumes...

A propane torch can certainly heat zinc to the point of giving off fumes, but once you've gotten it that hot, you won't have any luck soldering anyway. Zinc shouldn't fume at soldering temperatures.

 

[zippy97]

A propane torch can certainly heat zinc to the point of giving off fumes, but once you've gotten it that hot, you won't have any luck soldering anyway. Zinc shouldn't fume at soldering temperatures.

Okay, that sounds good. Thanks very much.

 

[Garage-ist 2]

Solid insights. Great question, Zippy97. Thank you.

 

[zippy97]

Solid insights. Great question, Zippy97. Thank you.

Glad it helped you buddy. I am learning as I go... I'm Hoping to pick up some sheet metal from the depot tomorrow and give 'Er a go. I've been practicing soldering coup cans and am sort of getting the hang of it. Making some fairly strong joints (I can't break them without a ton of effort), they just don't look great. I'll keep learning. Time to practice on proper steel instead of dented, bowed, and crinkled up steel cans.

With that said, I guess only newbs blame their tools/material. Lol.

 

[zippy97]

And here is some of the stupid s&#@ I've soldered together out of soup cans. It looks like utter ****. But I never ever learned shop skills prior to this. It's a new undertaking and eventually my stuff might look prettier. I had to YouTube how to even use a propane torch because I was scared I'd blow up my garage!

It partially looks so crappy because I done tons of practice joints on these pieces before I made my awful sculpture. So there's pools of old solder on the pieces from joints I re-melted and disconnected. Lol.

Maybe you guys will get a kick out of my poor man's soup can sculpture!! Lol.

 

[Lwel9226]

And here is some of the stupid s&#@ I've soldered together out of soup cans. It looks like utter ****. But I never ever learned shop skills prior to this. It's a new undertaking and eventually my stuff might look prettier. I had to YouTube how to even use a propane torch because I was scared I'd blow up my garage!

It partially looks so crappy because I done tons of practice joints on these pieces before I made my awful sculpture. So there's pools of old solder on the pieces from joints I re-melted and disconnected. Lol.

Maybe you guys will get a kick out of my poor man's soup can sculpture!! Lol.

You are trying and learning..... GOOD ONYA....

LynnW

 

[southalabama]

There are no mistakes. Only happy accidents.

Keep creating.

 

[rlitman]

...It partially looks so crappy because I done tons of practice joints on these pieces before I made my awful sculpture...

No, it's because you're using way too much heat.

Soldering is about heat balance. You need to heat the piece hot enough to get the solder flowing, without overheating it to the point that it oxidizes (where it turns color).

When soldering copper (what most people here will have experience with), you use a propane plumber's torch, because copper is very thermally conductive. The copper draws a lot of heat away from where you're heating, so you need extra heat to get the spot hot enough to melt the solder.

But that can's steel. Steel isn't all that thermally conductive, so the heat stays where you put it, and to make matters worse, that steel is much thinner than copper pipe, so it's even less of a heat sink. If I were soldering your sculptures, I'd be using my pocket butane torch (like a cigar lighter). With a propane torch, it would be incredibly difficult to keep it from running away on you, as you have discovered.

 

[zippy97]

That is a good insight. Thanks rlitman. I'm going to cut up a new can and give it a whirl again today. You're right, it oxidizes very fast. I held the torch on it at full blast for the heck of it just to see how hot it could get. Gets piping hot very fast!! You can make all kinds of colours by just holding the torch on full blast for 20 seconds

 

[rlitman]

That is a good insight. Thanks rlitman. I'm going to cut up a new can and give it a whirl again today. You're right, it oxidizes very fast. I held the torch on it at full blast for the heck of it just to see how hot it could get. Gets piping hot very fast!! You can make all kinds of colours by just holding the torch on full blast for 20 seconds

A little more than that with a propane torch, and you'll have it glowing. Just do that outside and stay away from the zinc fumes. And once you've burned it like that, forget about getting solder to stick.

Still, because steel is such a poor thermal conductor, you can solder one spot and later on heat another (quickly) to the point of developing color, without necessarily melting the previously mentioned solder.

 

[zippy97]

And once you've burned it like that, forget about getting solder to stick.

I have no business continuing to burn the steel like that (it was just for curiosity's sake) - but could you explain why solder won't stick after it's been heated to stupid hot temps? Is it because too much oxide begins to form? Just curious... trying to learn how metals work... My buddy is a materials engineer but I don't bother him with my silly basic questions.

 

[rlitman]

I have no business continuing to burn the steel like that (it was just for curiosity's sake) - but could you explain why solder won't stick after it's been heated to stupid hot temps? Is it because too much oxide begins to form? Just curious... trying to learn how metals work... My buddy is a materials engineer but I don't bother him with my silly basic questions.

Yes, it's about the oxides. Solder will stick to clean metal, but not to the oxides. Flux can wash away some of the oxides, and it also prevents a heavy oxide layer from instantly forming as you heat it, but flux will not remove a heavy oxide layer by itself.

 

[BD1]

Depending on the galvanizing, soaking pieces in white vinegar will work.

I made these cattails using sheetmetal galvanized strips that I soaked in white vinegar. I let these soak for 24 hours. It did a good job and the finish was a gray color .

 

[Sumboodie]

However I've heard heating up galvanized steel gives off very toxic fumes.

It's not great to breathe in (zinc), but it's by no means very toxic.

 

[zippy97]

Depending on the galvanizing, soaking pieces in white vinegar will work.



I made these cattails using sheetmetal galvanized strips that I soaked in white vinegar. I let these soak for 24 hours. It did a good job and the finish was a gray color .

Those are right pretty. Do you know what gauge of metal those were made from? Very nice

 

[BD1]

Those are right pretty. Do you know what gauge of metal those were made from? Very nice

Thanks, that is all 24 gauge . Here's another with 2" wide strips.

 

[zippy97]

Nice. I decided to not go with galvanized 26 gauge because regular 24 gauge was cheaper at home crapo. Will be picking it up today from the curbside pickup. Just went with a 12x24" sheet for now.

Would like to see about buying scraps from a metal recycler. There's only one recycling place that *sells* metal in town and they have some bad reviews on google. Still it might be worth a shot.

There is a guy selling 18 gauge off cuts on Kijiji but they are wonky sizes and thicker than I would like. Have checked Facebook marketplace and haven't seen anything. Just ads from scrap guys begging for free scrap metal. Leave some for me you nit wits. Lol.

 

[BD1]

I like 24 gauge for most projects. It is easily formed without special equipment.
I buy in 4x8 sheets which is definitely cheap compared to box stores. I haven't bought any in a year and a half with the Covid situation, so no idea what current prices are.
Buying from metal suppliers is definitely a savings. Purchasing drops ( cutoffs from a full sheet ) maybe an option.


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[Monza Harry]

Some of those "Scrappers" will sell that stuff as long as you are willing to make them "Rich" galvanized usually pays significantly less than "Clean" steel it is only a post on-line to find out or be told to ... Certainly worth a shot to me if in need/want. Harry