Identifying galvanized?

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Are there any good tricks to identifying galvanized metal? Sometimes it's obvious, but I do a lot of found object/scrap art stuff, and I'm trying to avoid working on galvanized when I can. It can be hard to figure out if a bolt or machine cover plate is galvanized or what the coating is to protect it.
Reply:If health and safety are truly a concern, there aren't too many of the platings or coatings that are any healthier than the various galvies. Many are worse in fact. Galvy is one of the less toxic of coatings. Your best policy would be "if it is coated, don't".."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Thanks, I hadn't thought of that. I typically wear a respirator with organic vapor filters - is that enough to protect me? Is welding outdoors with a light breeze enough?
Reply:Maybe do a bit of research on osha, or maybe someone here knows, the preferred filter for hexavalent chrome and cadmium. Those would likely be the two most dangerous you're going to encounter with off the shelf coatings. I'm really the wrong guy to talk to when it comes to health and safety. I've been a smoker since I was 13."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:I weld over zinc plated stuff, but I'm outdoors, use a fan (stick welding only) and I hold my breath. Stay upwind if you can.  When using a fan, I'll just use a typical Walmart style "box fan" and set it up next to my welding bench.  I position it to "suck" instead of "blowing" the plume away.   I'll also use the wind to my advantage.  Another thing that May or may not be feasible would be to grind off the coating at the weld joint prior to welding it.  But don't inhale the grinding dust without the proper respirator or use the wind to your advantage and hold your breath again. There's two "coatings" we use on top of zinc and it's various sub coatings (ie, tin-zinc, zinc-nickel, zinc-cobalt etc...). Actually there's more, but these two are the most prevalent.  Hexavalent Chromium and  Trivalent Chromium.  I can tell just by looking at a part if it's plated "yellow" (aka: "type II" in the industry) whether or not it's hex or tri chrome.  Yellow is not the only color however.  The Hex chrome is the real bad one for us mortal humans, while the safer tri chrome is replacing the former.  Also, welding stainless steel, naturally produces and gives off hexavalent chromium within the smoke.Cadmium is another bad one to inhale.  It is naturally a dull grey color (prior to coating it with hexavalent chromium) similar to tin-zinc.  However, unless someone shows you the differences in person and you've been doing it for a while, the average person can't tell what is what for many electroplated surface coatings. Basically what Sandy said about avoiding all "coatings" if you're not proficient in using steps to avoid the smoke plume, would be your best piece of advice.   They make respirators that remove various contaminants but you'd have to do some research on Google to find the one that works for you, depending on the material you're welding on.  Have you perhaps considered using a welding smoke/fume extractor?  Several companies make them such as Lincoln and Avani, but they're  expensive.  But, how much are your lungs and other organs worth to you?Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Good info, thanks SuperArc. I weld exclusively outdoors, so that helps. I"m going to look into proper filters for my respirator, that's probably the simplest and safest route for me.
Reply:You should be using respirators rated for welding fumes, such as the 3M 8214 or the P100 filters for half-mask respirators.For smaller objects, a bucket of muriatic acid diluted 50/50 with water will remove galvanizing and zinc chromate coatings as well as rust. You need to rinse the parts well and dry them immediately or they will re-rust.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Not to change the subject here but have ya ever looked at the MSDS sheet on mig welding wire or SMAW electrodes. Some nasty stuff in those too.93 Bobcat 225GMillerMatic 135HF Tig 91811
Reply:Originally Posted by Silicon-basedYou should be using respirators rated for welding fumes, such as the 3M 8214 or the P100 filters for half-mask respirators.For smaller objects, a bucket of muriatic acid diluted 50/50 with water will remove galvanizing and zinc chromate coatings as well as rust. You need to rinse the parts well and dry them immediately or they will re-rust.John
Reply:Originally Posted by Silicon-basedFor smaller objects, a bucket of muriatic acid diluted 50/50 with water will remove galvanizing and zinc chromate coatings as well as rust. You need to rinse the parts well and dry them immediately or they will re-rust.John
Reply:Originally Posted by SuperArcThe problem (maybe) with acids on steel is that is introduces hydrogen to the base metal, thus hydrogen embrittlement results from acids (and/or "pickling" in the electroplating industry.
Reply:Originally Posted by DeuceTrinalGood info on the acid, thanks. I currently have a sulphuric acid bath setup for my brazing work, I might give that a go too. Interesting recommendations on the respirators, I currently use a half mask with organic vapor filters that appears to be much higher level of protection than the 8214. The P100 is the designation for particulate filter, which I use for my woodworking (pink filters). They make a number of P100+organic vapor cartridges, I'll probably pick a set of those up.
Reply:Originally Posted by 4sfedBack to the OP's original question . . . a drop of dilute acid on a suspect part will cause zinc or cadmium plating to foam.  There will be no reaction on bare steel.
Reply:Originally Posted by Silicon-basedThe OP stated that he was using the galvanized parts for metal sculpture so I doubt that hydrogen embrittlement will be a major concern.John
Reply:Originally Posted by SuperArcVery true and I misread right over that part.  4sfed....You're correct, but missing a little bit of information. The RE-introduction of acid over a plated part (because acid was originally used in the plating process already), compounds or increases hydrogen embrittlement cumulatively into existing micro fissures that were originally created from the original plating process.   An analogy is like tooth decay.   For the condition never gets better but only worse with continuous sugar introduction on the enamel, no matter how much one brushes.
Reply:Originally Posted by 4sfedHopefully, we didn't just lose the rest of the readers.
Reply:I learned something here from both you guys.  "Hey I didn't come to look and learn, I came to turn and burn.... If I can't light up, I'm gonna light out!"-JodyIdealarc 250 "Fatman"MM 252MM 211 "Little boy" Victor Torches
Reply:Originally Posted by 4sfedNo argument there.  My point is that removing the plating prevents intergranular penetration of the zinc during welding, which can result in cracking without any external stress being applied.  There is no rule of thumb that can predict which process will cause more damage . . . therefore YMMV.    Removing the plating mechanically would be preferred as it prevents additional etching and would remove some or all fissures from plating. Hopefully, we didn't just lose the rest of the readers.