Outdoor powder coating touch-up

Truck bed liner. 5 gal bucket and a couple of brushes at wallmart was about $40.00. Used it on the frame of a '38 Buick Special four years ago. Tough stuff and you won't likely have to ever repaint it.

Big boys who make cheap fences powder coat, and use mechanical fasteners. Field powdercoating is not very feasible. I have never heard of anyone doing it. Big boys who make high end fences dont powdercoat- its not a good longterm finish for outdoor metalwork. One of the reasons is you cant touch it up, but there are others. Once rust starts on powdercoating, and it can start if someone scratches the surface accidentally or intentionally, it will cause the powder finish to peel up like a bad sunburn. Then, the only answer is to take the whole fence back down, put it in a

2500 degree burnout oven, then sandblast, then repaint. I sometimes build very expensive fences. I either use hot dip galvanizing, or stainless steel. I dont trust powder for exterior uses.

I have sent several powdercoaters kids to college on what I have paid for finishing furniture, and other things to be used indoors, but I dont use it outside. I just dont want the callbacks. Plus, some colors will fade in the sun, and some powders will chalk up outdoors. The truck liner paint is not a bad idea- that stuff is bulletproof. Normal painting protocol for a fence would be Sandblast Prime twice Finish coat with a very high quality enamel, or a two part epoxy system. Not sure what is still available in California. Many industrial suppliers like Grainger may still sell industrial enamels, even though you cant get it from home depot.

Check this stuff out:

It's about $80 a gallon, but if it performs as promised, it's worth it's weight in gold. I'm trying out a sample on some pretty brutal equipment applications. They have some pretty big pipeline and tank jobs referenced.

they don't seem to mention where you can actually buy the product on the website, do you have any more information on where to get it at?

I have some info at work, I'll bring it home and send it to you.

"Alan Frisbie" wrote in message news: snipped-for-privacy@Flying-Disk.com...

Powder is nice stuff BUT it can be interesting to work with. The BIG item is surface prep. Any oil/grease rust MUST be removed and the surface cleaned real well or the powder will fail. That is the number one reason for coating failures. As for touching up powder it can be done but is not easy. What you would need to do is get a small amount of the SAME powder they use to coat the parts. Then in the areas your planning on welding grind the powder back an inch or so then weld. Dress the weld and clean the area real well. Mask off the areas next to the coated spot to keep any loose powder from sticking during the touch-up. Then use a high temperature heat gun (NO TORCHES, they will leave contaminants or moisture on the surface) to heat the area up to 250-300 degrees and apply the powder ( one of the cheap powder guns from HF will work fine or you can just blow it on from your hand IF your careful) Then keep the area at 250-300 (watch the powder, it will melt and flow out at the proper temperature) Keep it at that temp. for 20 min. or so. That will cure the powder and it should match the original since it is the same stuff. Make SURE they use a good UV stabilized Polyester powder since the Epoxy powders and most of the blends will chalk in a year or so. Another option is a flame spray coater, they can do powder or metal coat in an exterior setting without a problem. But it is more expensive than oven baked powder and I don't think it is as durable. If you want to go with a conventional paint, a GOOD coat of Catalyzed Enamel base with a heavy clear would hold up 10 years or more.

Thanks for all the great replies to my questions! Now that I understand the issues a bit more, I'm beginning to reconsider my decision to powder coat. As I now understand it, powder coating is great as long as there is no way rust can get under it. This means no chipping or cracking.

For an outdoor fence, that may be impossible over the long run. Gates get slammed, garden tools fall against them, lawn mowers or string trimmers fling pebbles, etc. I'm going to take a fresh look at painting, especially some of the suggestions you guys made.

That Sci-Coat stuff looks interesting, but I want to see what it looks like first. Likewise the idea of using truck bed liner coating.

Outdoors sure is a severe environment! Nothing seems to stand up very well. I got some of those chrome plated wire shelf units for my wife to keep her collection of small cacti on. I figured that since chrome plated car bumpers seemed to last forever that the shelves would last a long time. Wrong! Only four years later they are all covered with a light coating of rust.

Even the "heavy duty" silver tarps can't last more than one year in the southern California sun. I wrapped a piece of equipment in one, and one year later the silver coating is flaking off and the underlying plastic is going fast. Mother Nature is about as agressive as they come!

Thanks! Alan

All chrome plating is definitely not created equal.

Before I used the truck bed liner, a good friend in FL painted an extra (throw away) set of motorcycle gas tanks with truck bed liner. Nominal clean up and prep work. Brushed the stuff on and let them sit in his yard for almost a year. We're talking Florida saltwater front property. He poured gas on them, let them bake in the sun, threw gravel at them, etc. I suggest you give that type of test a try and see what your results are. Mine were the same.

It's cheap, easy to apply, prep work is a piece of cake, and it really does last under extreme conditions. Tough stuff! You can brush it, roll it, or spray it also, but the spay cans are spendy and I've never used them.

Have you checked out hot dip galvanizing? Gives a zinc coating that protects both as a covering and as cathodic protection.

Tom

Yes, I did. The problem, as I mentioned in the original posting, is what to do after welding the various sections together. I'm not aware of any way to "touch up" hot dip galvanizing in the field. Is there one? Do the various zinc-containing paint products work well?

Of course, I am ignoring the aesthetic aspects of galvanizing. My wife might have something to say about that. :-)

Alan

Yes , there is. Clean the slag off the weld immediately after welding. While the weld is still hot, rub it with a "zinc stick". I believe that it is just that, a stick of pure zinc. It will melt and run over the weld area. Zinc sticks are avilable here in Australia from BOC Pty Ltd. (Used to be commonwealth Industrail Gasses) but I would think most good welding supply organizations would have them available, even if they had to order them in for you.

Do the various

There is one here in Oz, called Cold Gal that works reasonably well but it will be long gone before the hot dip galvanized area starts to corrode

One product:

've never used it.