Galvanized Metal to Build a Planter Box

admin

Hi,I am looking to have a few simple cube planter boxes made and am unsure about what types of metals to use. Originally I was looking to have 16 gauge galvanized sheet metal cut and welded to create a cube planter box.  The planter would be subsequently powdercoated.  Main issue with this is that once welded the welded edges no longer are rust resistant and could rust through the powdercoat (over time or if chipped on the edges).  Since the planter will be powdercoated white, rust is not an option.I have also been offered the idea of having the planter fabricated and welded out of mild steel and subsequently galvanized and powdercoated.  However I have been told that since my sheet metal is too thin, hot dipping would not be ideal but instead should be electro galvanized.  I am unfamiliar with this process.  Would this method suit my needs?  Would the planter be resistant to rust over time?  Will the planter rust if the powdercoat is chipped?Any help would be greatly appreciated.Also, I should add that I am trying to avoid stainless and aluminium since it will not be cost effective.Thanks,Luke
Reply:electro-plating or electro-galvanizing will work for your application.  If the white powdercoat is chipped at some point in the future, the zinc galvanization will corrode and turn chalky white.  This will protect the underlying sheetmetal until all the zinc coating in the vicinity of the paint damage has been consumed.  Depending on the conditions(moisture, acid rain, salt water, etc) it could take months or years for the zinc galvanizing to fail locally, and allow the underlying sheetmetal to start rusting.I'm not certain that electro-galvanizing and powdercoating will be less expensive in the long run over stainless or aluminum.  You should investigate this further...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Is it possible to hot dip 16 gauge sheet metal?
Reply:Yes but the heat from the molten zinc bath will warp your 16 gauge sheet metal box  until it looks more like a crushed beer can.Hot dip is done on thick structural steel that can take the heat, chainlink fence where a bit of warping doesn't matter, and on sheet metal in the steel mill where they can iron out the wrinkles before sending the sheet to customers.electroplate is your best option for what you have, if you're bound and determined to galvanize it.  Personally, I'd coat the boxes with a zinc rich primer that your powdercoater approves of, and see what happens.  That and some proper drainage holes in the bottom will likely work..."Free advice is worth what you paid for it" Originally Posted by planterboxIs it possible to hot dip 16 gauge sheet metal?
Reply:Thanks so much for the info.My main issue is chipping.  Since this will be a cube, I have seen chips in the powdercoating on the corners.  If this happens won't the zinc primer/paint chip off as well?  Then the planter would rust either way?I was thinking of having the planter made of galvanized sheet metal.  Then either having the planter electroplated or treated with zinc paint to protect the welds.  Then powdercoated.  In this case would the electroplate or paint work better for me?Thanks again for the responses.
Reply:Yes, if you chip off the coating and primer, then the underlying steel will rust.If you make the box from galvanized sheet metal to start with, then there are problems with welding galvanized.  The zinc must be removed mechanically(sanding/grinding) or chemically(acid) from the area being welded.  Fumes from welding overtop of zinc galvanizing are toxic.If you decide to start with galvanized sheet, follow safe welding procedures, then yes, the finished welds can be coated with zinc primer and the whole powdercoated.  If the corners are the most vulnerable spot then this still leaves you with the problem of the paint chipping and the corners rusting.This is why I encourage you to rethink the cost of using aluminum or stainless steel.  Aluminum would be my first choice.  Once you deal with all the issues surrounding use of galvanized sheet, I think you'll find that using Aluminum and finishing the aluminum with a clear enamel, will give you better results for not so much more money.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thanks again.  Last question.  Which would be better for avoiding rust in your opinion?1. If I use galvanized steel and have it welded and then have the welds sprayed with a zinc primer then powdercoated.2. If I use mild steel and have it welded then electro galvanized then powdercoated.Would rust spread if the powdercoat was chipped for these options?Thanks again!
Reply:Originally Posted by planterboxThanks again.  Last question.  Which would be better for avoiding rust in your opinion?1. If I use galvanized steel and have it welded and then have the welds sprayed with a zinc primer then powdercoated.2. If I use mild steel and have it welded then electro galvanized then powdercoated.Would rust spread if the powdercoat was chipped for these options?Thanks again!
Reply:Aluminum is going to be your best material here. No matter what you do with the galv. there will always be a chace of a rust problem.
Reply:Aluminumb is notb as expensive as you might think. Pound for pound, youb get 3 times as much. Factor in the finish cost and it actually end up cheaper.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.