jwihak Posted March 27, 2008 Share Posted March 27, 2008 Hi there, I'm new to the forum and have no experience whatsoever with blacksmithing at all (as will become evident). But I have a unique scenario I'm hoping someone can help me with. I'm doing Props on a film in which the characters are supposed to be cutting, welding and grinding road sign posts into makeshift spears, using both oxy-acetaline and an angle grinder. From what I gather, doing so with galvanized road signs is highly toxic. This being a movie, we want to be able to see the characters' faces so they won't be wearing masks. So I'm wondering if there is a fast and effective way to strip these galvanized posts of their coating so that the actors can safely cut, grind and weld without breathing in toxic fumes. I've heard it suggested that you can sandblast the galvanizing coating off and have tried this. It seems to be stripped, but I'm concerned that while it may rid the outside of the post of the coating there may be some that leeches into the metal and would still be there when you take the torch or grinder to it. Any suggestions or hints would be greatly appreciated. Thanks in advance. Jordy Quote Link to comment Share on other sites More sharing options...
teejay Posted March 27, 2008 Share Posted March 27, 2008 Buy some black pipe and paint it silver,that keeps everyone healthy!! Quote Link to comment Share on other sites More sharing options...
Glenn Posted March 27, 2008 Share Posted March 27, 2008 Please keep the answers on site so other folks can read and benefit from the knowledge presented. Quote Link to comment Share on other sites More sharing options...
agsolder Posted March 27, 2008 Share Posted March 27, 2008 Anybody who oxy-acetylene welds or cuts anything without a mask to protect vision, or who grinds anything, galvanized or not, without eye and respiratory protection-- a mask with filters-- is a fool. Couldn't these enterprising souls just stick the ends of the posts in a fire, outdoors, plenty of breeze to blow the nasties away, and then use a hammer to put the points on? Send my standard moom pitcher consulting fee plus demurrage to Glenn as a contribution to the site fund drive. Quote Link to comment Share on other sites More sharing options...
Ice Czar Posted March 27, 2008 Share Posted March 27, 2008 provided its throughly blasted, there should be no zinc leaching into the steel there is no "leaching" mechanism, it can also be etched off with acidsGalvanization On the other hand, what alloy of steel those posts are I can't say, there are elements employed for corrosion resistance its best not to inhale, toxic metals like chromium and nickle. Think the prop deparment should just fabricate some sign posts from mild steel, shouldnt be very hard. A sandblast finish will be a nice silver without the paint which is likely as toxic when burned. For a reality check if you have access to acetylene you have improvised ordinance, a low tech solution in keeping with the end product would be wood to charcoal a hole in the ground a hammer and something hard to pound against. the producer could be socially conscious and have the actors improvise safety equipment, or alternately cough up a lung or burn out a retina on screen, to a pithy macho remark :p Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 27, 2008 Share Posted March 27, 2008 All above are good examples and the first sentense of agsolder's post most definetly should be heeded. May I add using muratic acid. place end of post in container of the acid and leave until the bubbles stop forming, rinse and dry. But I believe the black pipe painted silver as teejay states is the best way to go. If you use an anvil could you ship to me when the movie is completed!?! ;) Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 27, 2008 Share Posted March 27, 2008 It's not a problem of leeching but hot dipped galvanization should be on the inside of the pipe as well where you can't reach it sandblasting. The HCl, (muriatic) acid dip should work for the insides as well as the outsides; but taking some black square tubing and making it look like the real stuff would be easier! Note if you paint don't use paint containing cold galvanizing materials---zinc It would be a good idea to provide positive ventilation so that all fumes/dust/etc goes away from the cast and the crew. Safety equipment is mandatory! Talk with your insurance agent about not wanting to use it for the cast and see them transform into a gibbering enraged maniac. So how to deal with both needs? Make safety gear that *looks* like it was cobbled together; or shoot the closeups seperately when there is nothing going on using lighting to suggest the work reflecting on their faces. Note that doing so may encouraged idjits to try it for reasl without safety equipment and so be ready for the lawsuits for blindness. Quote Link to comment Share on other sites More sharing options...
matt87 Posted March 27, 2008 Share Posted March 27, 2008 May I ask where they're powering angle-grinders from? Mains electricity would likely be conspicuous by its absence in a fan-hits-the-air scenario. Also, o/a rigs aren't very common outside of well-equipped metal shops, where there is also lots of metal. Apologies if these comments aren't any use to you. Quote Link to comment Share on other sites More sharing options...
Dave M Posted March 27, 2008 Share Posted March 27, 2008 Most metal suppliers carry hot rolled steel T stock and chanel stock of differnt sizes, this looks like the stock that they galvanize for sign posts so it would look realistic. Just sand it up to give it a shine but if it is the end of the world movie goers expect every thing to be all rusty anyways. Heavy metal poisoning is not worth the risk.:( Quote Link to comment Share on other sites More sharing options...
Ian Posted March 27, 2008 Share Posted March 27, 2008 "Keeping it real" in a post apocalyptic world...... Characters find sign posts, tear them down. Take them back to basecamp. Build big, BIG bonfire (always looks good on film) and throw signs in fire from upwind. Go have tea and cakes well upwind and in a brooding way until fires burned out. Recover signs (now happily free of nasties) and set to making spears. They would have some sort of safety gear for Oxy cutting and for welding, no ifs buts or maybe's. Its a fundamental. Now grinding without eye protection is indeed 'do-able' but in a very similar way that russian roullette is 'do-able', not my kind of odds. You have to assume the characters have some smarts, if not them then certainly your adience has, and will hoot and cat call all thats not right. Quote Link to comment Share on other sites More sharing options...
GrandLordKhorne Posted March 27, 2008 Share Posted March 27, 2008 I would suggest that you just get a different type of sign post all together, as in none galv panted type and strip the paint. Or get channel style posts and sand blast them. Or like a lot have suggested black pipe sandblasted. Having said that, I would make 3 comments about movies and props. #1: Lots of morons imitate movies, I completely agree with what everyone has said about social responsibility. Show the actors wearing proper PPE. If you ruin oxy/fuel for me in the way the F&F ruined sporty cars, I will be vary unhappy. Or think of it this way: most actors are morons anyways. Let them get Zink poisoning and then have a news cast about how actors died from being dumb so that the world can learn a lesson in safety. #2: In reality I have seen a lot of movies where actors put on proper PPE to do things like cut and weld, I think it can be done tastefully and if your just not going to try than your just not being creative about it. A movie is a form of art and if you lack creativity than you are not doing good art…. Don’t do art just for the sake of doing it or you are just making more worthless white noise, be creative and make it mean something. #3: It has been stated before, but… There are a lot of things in movies that seam dumb, like some of the lines in F&F that make sense (man I hate that movie), how really rare things can be found in abundance in abandoned barns and so forth. From a realistic standpoint, if you do not want to alienate the viewers that may know something about Oxy/Fuel or welding, you might think about how dumb it sounds that they have sign posts and oxy/fuel gear with not other source of steel around…. Realistically previous statements are exactly right, I can not think of one place with oxy/fuel where the improvised armament of choice would be made of sign posts…. Not even in a sign post manufacturing shop would that be true. I just want to point out a couple of places in movies where I think misuse of metalworking makes me feel like movie people do not think or do research: I will stick to my two fav. Pirates of the Caribbean: Swinging the sword around in the blacksmith shop that stays glowing for a long time for something being swung around like that and has an edge even though still in the forging phase and having been left in the fire while he was gone away for an extend period of time. It also performs really well for something that would not have been heat treated yet and sparks with strikes… Ghost Ship: They make a lovely underwater oxy/fuel weld without filler metal, using a flame the size of a lighters coming from a cutting head. If you are wondering, oxy/fuel dose not work underwater. OK, said my piece… Quote Link to comment Share on other sites More sharing options...
rthibeau Posted March 27, 2008 Share Posted March 27, 2008 Spears for what? Having found a place where there was a useable oxy/acet torch setup waiting for them to use, they should just cut up the large picket fence across the street that already has spearpoint finials....and round pickets already suitable as spear shafts. The big gate attached to it would have pieces for axes and knives and other weapons. Have your people contact my people. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 27, 2008 Share Posted March 27, 2008 Well you can *cut* under water with O-A if you do it right. Quote Link to comment Share on other sites More sharing options...
nett Posted March 27, 2008 Share Posted March 27, 2008 Well you can *cut* under water with O-A if you do it right. That's a trick that Mike Nelson showed us many years ago.;) Quote Link to comment Share on other sites More sharing options...
habu68 Posted March 28, 2008 Share Posted March 28, 2008 If you have O-A you have a powerful explosive and carbide(acetylene) cannon. Dont take a spear to a gunfight. contact me off string for my pop bottle, drive shaft mortar plans. Grin. Quote Link to comment Share on other sites More sharing options...
GrandLordKhorne Posted March 28, 2008 Share Posted March 28, 2008 Yes, you are right, you can ‘cut’ under water with oxy/fuel, though, I would haft to say it is limited… But welding is a completely different game, particularly with a cutting tip and no filler metal. Watch the beginning of Ghost Ship, you will see what I mean, they are laying close to 4 inches of bead a second with no filler metal underwater with a cutting head on a none prepped surface, in the ocean, with positive water pressure on the patch they are installing from the inside (thing is sinking fast threw the flooding caused by the hole they are plugging, even cutting with oxy/fuel under fast running water dose not work) and the weld looks like robotic TIG… For some one like me that was trained as a hard hat diver, that is such a joke, it’s like watching a cooking show where they pretend to make bread by leaving meat in a cold oven for a few seconds. Having said that, I like the fence idea. But the tools in a metalworking shop are generally more effective weapons that spears. So I also like the improvised explosive statements. Quote Link to comment Share on other sites More sharing options...
welder19 Posted March 28, 2008 Share Posted March 28, 2008 Being as your in the movie bussiness why not just find the company the manufactures the sign posts and buy some from them before they are galvanized? welder19 Quote Link to comment Share on other sites More sharing options...
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