Remove Galvanization with Acid – Hackett How-To

Remove Galvanization with Acid – Hackett How-To


Conduit– it’s available everywhere. You can get it for cheap from any hardware
store; you can get it for free from any abandoned or not-so-abandoned building. I want to weld these two pieces of conduit
together. Problem: the structural steel that you want it cladded in a very thin, very very
toxic layer of galvanization. If I weld, they’re probably going to stick,
but the galvanization will burn and boil off and it will poison me. Also it makes the weld
not so great. I’m going to show you how to get rid of the
galvanization thoroughly, effectively, and quickly using a material that you can get
in any hardware store or have around the house. Galvanization is a protective coating that’s
laid down over steel to keep it from rusting. It’s a mix of different heavy metals, usually
zinc. And you can tell if something is galvanized
when it has this dullish grey cast to it, and secondly you can see a crystalline structure
in it, the way that it’s laid down when it’s in the pickling bath or whatever they use
to galvanize. One solution, and a solution that I’ve heard
from various metalworkers is take the metal and grind it. Things like conduit and most things that are
galvanized aren’t just galvanized on the outside, they’re also galvanized on the inside. How am I going to get a grinder into there?
It’s going to be difficult, I’m going to be there with a die grinder or a Dremel for hours.
Too much work. Instead of using mechanical means to get the
galvanization off, I’m going to use chemical means. Materials needed: a plastic cup to hold everything
in, the metal that you want to remove the galvanization from. Since we’re just stripping galv off the end,
just the part that we’re going to weld, it doesn’t have to take the whole rod, just the
part that you need to work on. Secondly, very importantly, muriatic acid. It’s a relatively dilute, like one third strength,
hydrochloric acid. So, decently strong, but not super strong. You can find it in any hardware store; it’s
usually in the meth lab section. And baking soda: a base to neutralize the
solution when we’re all done. I’ve got something to prop up my metal, in
this case it’s a gas can. I’m going to pour the acid in– at this point
you might want some gloves or goggles. What I like to do: I take a deep breath, I
stick the metal in the acid, and then I step away. A tale of heavy metal poisoning: I had this
really cool metal; it came from rooftop water tanks. I looked at it, and I didn’t see any crystalline
structure on it, so I didn’t think it was galvanized. And it had this dull reddishness to it that
I thought was a thin layer of rust. Figured it was one of those steels like COR-TEN or
whatever that would just rust a little. That night when I was welding I was shaking
and sweating; horrible fever like I’ve never really had before. Went to sleep, slept for 16 hours. Later, I thought “Wait… maybe that metal
was galvanized, but in a way I haven’t seen before.” I had suffered whatever the final stage of
galvanization poisoning is. The only other stage after that is death. If I had done then what I’m showing you to
to do now, I probably wouldn’t have screwed up a couple of really important meetings,
I wouldn’t have gotten horribly horribly ill, and life in general would be a lot better. So over here you can see a pretty sharp line–
that was the level of the acid. Below that, it’s just dull straight uncoated
steel. It’s already starting to oxidize, if I leave
it out for another twenty minutes it will probably be red with rust. Above there is a layer that I think it might
be degalvanized. That’s where the fumes from the acid rose up, you can see it on this one. And then up above that, straight up galvanized
metal. Look at the color difference. This: galvanized.
This: maybe galvanized, I don’t think so, and then this: bare steel. I used the acid to get the galvanization off
the inside as well as the outside of the pipe, now I need to get the acid off the inside
of the pipe. So I’m making a solution of water and baking
soda, and then dip that in. Muriatic acid: one of the things it’s commonly
used for is cleaning cement. If you dilute it out with water, especially
if you neutralize it first, you can dump it down the drain. You’re no longer dumping down an acid, you’re
dumping down a salt– I’m not sure which salt it is– and water. If you were to spill this on your workspace
floor or on your assistant, and you want to neutralize it, just dump some baking soda
on it. For example: oh no, a spill of acid! Baking soda will fix it! Ta-da, science! After neutralizing the acid with baking soda,
I rinsed these off in the sink to clean them off and you can see where it’s already starting
to rust. The galvanization is gone. However the galvanization was gone very very
quickly, in just the violent part of the acid reaction. Later it just burbled burbled burbled slowly. That slow burbling was the acid eating the
steel. We left it in for longer than we should have,
and you can feel a ridge here in between the original thickness and the thickness it was
eaten down to. I know that’s not just missing galvanization
since it’s only a few molecules thick. I’m just doing a quick and dirty join. I’m not going to make it fancy, I’m not fish-mouthing
this to get a good, tight fit up, I’m just sticking two pieces of metal together just
to show it will not boil out galvanization and it should make a pretty decent weld. Not the prettiest weld, but when you don’t
fish-mouth tube, you have a lot of gap to fill. But the important thing is that it looks like
it will hold, there’s no boiled away galvanization, around it, there’s no foaming, I didn’t get
sick. I’ve shown you how to degalvanize conduit
and turn something that’s everywhere but kinda useless into another useful thing. If you want to see some real science… is
this one on camera? Yeah. Oh, science! SCIENCE! Science, acid bubbling next to a can of gasoline,
what could possibly go wrong? Ahhh! A cheap easy way to get kicked out of every
science fair! “Sir, aren’t you a little old to be in this
science fair?” Don’t get in the way of my knowledge, la la la, security comes, then
you burn them with acid. I’ll show you who’s science now…

85 thoughts on “Remove Galvanization with Acid – Hackett How-To

  1. For more info on the ominous and awesomely named "Metal Fume Fever" take a look at the Wikipedia entry by that name. Tl;dr- it sucks. Do what the video says instead.

  2. Thanks for sharing this. VERY valuable information. I really wish I had known this in college when we where welding galv metal we found. Sending this to sculpture professors now.

  3. The baking soda will neutralize the remaining acid, but what about the zinc chloride produced: how unsafe is it to put that down the drain, and how could one extract it first?

  4. The acid strips away the paint as well- not sure if it gets dissolved directly (prob depends on the paint formulation) or just undercuts it. Actually, I can recall seeing the occasional shed snakeskin looking crap in the acid bath- that was prob the layer of paint, sloughed off intact.

  5. why are you going to all this trouble? an angle grinder & wire wheel with an inexpensive P-95 respirator (from any welding supply place) is perfect, replacing welding fumes with muriatic acid fumes..? you may have to trim your beard and line the edges of the respirator with petroleum jelly unless you shave clean. you should wear tig gloves and long sleeves! i'm familiar with madagascar (someone once tried to hook us up) & if you ever need a certified welder for a project let me know i'm nearby

  6. Wire wheel does not clear out the galv from the inside of the conduit. Also, as another commenter pointed out, there is sometimes paint on the inside of the conduit. I fully realize that there are other solutions, but tons of trial and error (mostly error. Lots and lots of error) make me think that acid is the best, and close to easiest, one. Thanks for the offer. Will reach out if we need you.

  7. You way seems like a lot more trouble to me, and it takes the zinc and flings it all over the shop. With the mask, you might not intake zinc while you're welding, but you will afterwards. Moreover, the grind and brush methode doesn't address the fact that there's zinc on the inside as well as outside the conduit. And, done outside or with a fan, the acid fumes are no problem. They're no more toxic than vinegar fumes. Just don't stick your head close to it. Luckily, you don't have to.

  8. One third strength is as strong as hydrochloric acid comes. Hydrochloric acid is an aqueous solution of hydrogen chloride. That is, it's hydrogen chloride dissolved in water. At standard pressure and temperature water can hold about 38% hydrogen chloride. Then it spontaneously fumes white hydrogen chloride gas. You see the fumes when you open a fresh bottle. If the fumes reach your lungs or eyes they turn back into hydrochloric acid and start to burn… So, 1/3 is effectively full strength.

  9. Tip: even very tightly sealed bottles of hydrochloric acid will give off hydrogren chloride fumes. The fumes quickly dissolve in moisture in the air near the bottle. This forms a small cloud of hydrochloric acid. After a few months anything made of metal within a few feet of the bottle will show corrosion. I found the bottles to be very difficult to seal. Eventually I started to store them outside.

  10. Fine in this instance as all you are producing is CO2 and table salt. However mixing an acid and a base can be very dangerous depending on what your mixing. Always always check what your mixing first and that its safe or you could end up with a face full of chlorine which is a lot worse than zinc fumes! Generally the safest and sure-fire way to neutralise an acid its just excessive dilution with water. Nice video though, good job.

  11. if you've stripped the inside you're going to need to rust proof it before welding as best you can.. because you won't be able to paint it afterwards..

  12. I've heard that wiping or bathing the object in vinegar or vinegar and water will (maybe not remove the galvanization, especially as quickly as muriatic acid) at least prep a surface for painting.  I don't know about welding though.  Your thoughts?

  13. "See, I'm not dead!  It works!"
    No, actually thanks, great advice.  But I'd use the acid bath plus a chemical mask when welding to be safe.

  14. At 1:47 — Did he really  say  the acid could be found at any hardware store "in the Meth Lab section".

  15. Old welders trick was to drink a large glass of buttermilk to keep from getting sick.I know it works. I don't know why.

  16. Just FYI, most galvanizing is done over layers of copper and tin. The final liquid is very toxic, so don't just pour it out on your grass. The toilet is probably the best place, and use as little acid as possible. You can find hydrochloric/muriatic acid in the concrete section of a hardware store. The red coatings are most likely red lead, and they are VERY bad to inhale.

  17. How toxic is the zinc? USDA say 300 mg Zn/d internal is bad. Guy is making the toxicity up. I think the dilute muric acid is more toxic. Meth lab section. Just weld.

  18. I am not someone who has any interest usually in celebrities. But I have to say I would love to shake Hackett's hand. Thanks for the videos

  19. His TV show was one of my favorites. Hackett is the real life MacGyver and one of the very few people I would want to be friends with after the zombie apocalypse. Someone needs to give this guy a show again.

  20. Hi, I've used muriatic acid to remove galvanization. Afterwards i wash the metals to clean acid coating ect. Tried to do welding with E6013 electrodes and the weld did not penetrate well? I got slag and impurities. Should i have grind the metals?

  21. @Becky Stern. were you his camera girl or what? I love Hackett, and miss seeing him in anything. I saw he's on the new Mythbuster's show thingy. glad to see him again. wanna see more.

  22. Just the exact info I've been looking for!!! Thanks!! This is gonna save me a few hundred Dollars!!!!

  23. i just use vinegar (like th giant pickle jars filled up with vinegar) and leave the pipes in there checking every couple of days

  24. "Fish-mouth" the pipes and no TIG gloves… even for me, the video is a little sketch. Breath the mist or gas from the bottle and you're in for a world of pain.
    Hackett Hack-it, I get it, yawn

  25. Thanks fort the vid. It's really instructive. We call muriatic acid "salfumán" or "agua fuerte" in Spanish. Be warned when using it, to carefully close the bottle or container, or else the vapors of such acid will rust everything they take contact with.

  26. This is no joke, me got a fever about 2-3days for no reason, maybe just a cold/flu, and a week after one man got the same fever, and yes, the day before we both do welding a galvanized wiremesh.

    Should we eat or drink something to neutralized the poison?

    I think about wearing a face mask after seeing your video, thanks for the info

  27. If someone ever gets Muriatic acid (Hydrochloric acid) on themselves … don't toss baking soda on them. Neutralizing HCl with base is a very exothermic reaction and generates a lot of heat. Instead, make sure to flush any area of the body that the acid came into contact with lots and lots of water.

  28. do you need a mask, im doing a experiment and professeer bean said That he knows for sure you need goggles?

  29. In my experience any (below) half decent rotary tool(the $8 harbor freight kit with the equivalent of probably $90 worth of accessories had you got them from Dremel, is enough for this) with effectively any material removing attachment(HSS routing bit, sanding drum, paper sanding discs, any of the stones, even the diamond bits for engraving would take under a minute to quickly remove the two surface's. Sure, depending on your bit of choice it may not be pretty, but it'd work and would be more cost effective and quicker depending on the task. On the other hand, this is precisely what I was looking for for doing things like galvanized cable, chains, or just large batches of parts that it makes more sense for!

  30. Fyi peoples. Muriatic acid or hydrochloric acid will cause even the highest qualities of stainless steel to oxidize or show signs of oxidization

  31. This guy is effing funny….. when I first saw him I knew he was bad news…. I am guessing he is on the no fly list!

  32. I build canopies with this.(cuz wind fks up the cheap Harbor ft ones)
    Never got sick yet after wire brushing, but I,m going to do this now. Great vid.

  33. I want to remove the galvanisation from a section of a part that will be welded but only around where the weld will be. Would you have to submerge the part in acid to remove the galvanisation or could you say soak a wipe in the acid then wipe down the part with this wipe so to only remove the galvanise around where the weld will be?

  34. Any idea how much of an area should be de-galvanized to ensure the radiant heat does not vaporize the remaining coating?

  35. You want a real acid/base science example, do this: Pick up a bottle of sulfuric acid (I believe it tested at 96% pure sulfuric acid, which is lab grade for a fraction of the price) drain opener (I was only able to find it at a single Walmart in my area) and a bottle of 100% lye drain opener (Lowe's was my only local source for it). WEAR ENOUGH PROTECTIVE EQUIPMENT ASSUMING IT WILL ALL BE THROWN INTO YOUR FACE. And then mix them. Afterwards, you not only got to see an interesting reaction, but you also are left with an extremely conductive liquid – sodium sulfate – which is fantastic (the best IMO) for electroplating metals

  36. Hello … Greetings from Chihuahua, Mexico. I have a Galvanized water tank. and I would like to build a bbq smoker. can I remove all Galvanized with acid. and smoke or grill meat? what do you think?

  37. i have a question… is it possible to weld a piece of galvanized pipe to spring steel, if cleaned off zinc as you recommend… i have a home made machete blade of spring steel, and i want to put a handle on it of old galvanized pipe i have… is that possible… thanks for the info…

  38. I went to the local hardware store but I couldn't remember the name of the acid so I told them I was looking for the meth lab section. They called the police and now I'm under surveillance

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