MIG weld through paint?

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Can I MIG weld through paint?  I have a big ol' piece (42"x96") of 3/8" thick mild steel that I want use as the top of my welding table.  It appears to have paint on it - I thought it was rust, but its reddish brown paint. Do  I have to grind away the paint where I want to weld it to the frame?  Since its already resting on the frame (all 400 lbs of it), lying on my back grinding for an hour doesn't sound very fun.
Reply:you don't HAVE to grind it. But I would. It shouldn't take an hour. It's gonna be some nasty weak welds and fire and fumes if you don't.
Reply:Grind it.Remember, you dont need to weld all of it up solid either.  Just grind a few spots, and weld it up.
Reply:IT WILL GIVE YOU A POOR GROUND, SMOKE AND PORISITY IN YOUR WELDS..............grind away dude !!!!brian
Reply:Holy moley, make sure it isn;t lead based paint, or if it is, ventilate!
Reply:In a perfect world you would grind but in the real world you can do a slight forward whip to burn the crap out as you move forward.Your weld is intended to locate the plate rather than suspend the weight of the plate.
Reply:Okay, the paint has been grinded away and I'm ready to weld.  I've never done an "overhead" fillet weld.  Got any pointers?
Reply:Normally you run small stringer beads.  I use a leading angle that is relatively extreme.  Your nozzle will pickup a lot of spatter which you have to clear out regularly.
Reply:I think paint is better than rust, instead of grinding I might have taken a torch and burned it off.www.urkafarms.com
Reply:I've got to repair alot of freshly painted things and noticed that if I didn't do a good job, the weld dosn't like to blend in too well.. So the answer for me is to crank it up hotter.  This is all done with .035 mig with co2.  I've torched paint off but still had to go back with a wire brush.  MIG is to picky when it comes to clean surfaces, that's why I like to burn rod in situations where prep times are high.  I can half/*** the prep and make up for it with rod.Common sense in an uncommon degree is what the world calls wisdom.
Reply:Well I don't have a torch (yet) and now iI face the challenge of removing the paint from the entire top surface (28 sq ft).  Is a flap disk the best bet?  I don't want to gouge the surface.
Reply:Originally posted by WillyWeld Well I don't have a torch (yet) and now iI face the challenge of removing the paint from the entire top surface (28 sq ft).  Is a flap disk the best bet?  I don't want to gouge the surface.
Reply:Sometimes paint can be scraped off with a home made scraper.  I have used a chunk of sawmill chipper blade on the end of a bar.  The other choice is a really coarse sanding disc like 36 grit.
Reply:After 2 1/2 weeks (30 mins here, 30 mins there), 2 cans of chemical stripper, 3 flap disks, one wire wheel, I've removed 3/4s of the paint from the top of the welding table.  This sucks, but the end is in sight.  I certainly learned a lesson the hard way (pay for NEW steel).   I'll post a picture of the finished table under "projects" hopefully next week.
Reply:Could build a big fire under it.Common sense in an uncommon degree is what the world calls wisdom.
Reply:why did you have to grind/strip the whole thing ?what kind of frame does the table have ?A few inches of weld here and there on each side and each end would do the trick.  Shouldn't have taken more than an hour to prep for welding and weld it.
Reply:In getting the paint off of the whole surface, I assume we are talking about the topside now, right?Since it's just paint, I might use a belt sander with big grit if one was available.  If you use a grinder with flap-disk, the bigger it is, the faster you'll be done.
Reply:For an area like this where you want to weld table to legs a scraping with knife will work well, I use a 3 sided knife in this situation. I definitly would grind all paint off of table top though.When welding an overhead weld I would weave side to side and she'll sink in good.J P Streets Welding LLC
Reply:I grinded away lots of small areas on the underside for welding to the frame with two inch long welds.  I was surprised at how well the overhead welds turned out compared to my vertical welds on the legs of the frame (some were pretty ugly).  Let's just say I need a lot more practice on vertical fillet welds.  I like the belt sander idea for the top surface.  I'll try that tonight.  The frame is made up of 2x2 and 1.5 x1.5 square tube.  Its nice and beefy to hold up the 400+ lb table top.
Reply:The belt sander seems to work a little better (50 grit).  I did another square foot in about 30 mins.  Just a little more left to do...(see pic if it shows up) Attached Images
Reply:Too bad the EPA outlawed all the good chemicals! The DEA did too but that is a different problem. lolololRon ShopFloorTalk Millermatic 350P, M-25, M-40 gunsDynasty 300DX, Coolmate 3, Crafter CS-310 TorchTrailblazer 302, 12RC, WC-2430A spoolgunSpectrum 2050Thermal Arc Plasma Welder PS-3000/WC-100B
Reply:Finally the grinding is done!  I posted a picture of my new table under "projects".