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Painting Shop Built Steel Structures

dksoba

Hot Rolled
Joined
Apr 8, 2011
Location
San Diego
I have built several structures from steel tubing that are TIG welded for my shop (partly for the purpose of learning to TIG weld, partly to gain fabrication experience, and partly because the structure itself is needed). Of the four structures built, I have painted two of them and I haven't really been satisfied with the results and/or the process. I am getting ready to build some shelves or a mezzanine but before I do so I'd like to have my painting procedure sorted out. So far, I only have experience with Rustoleum products. I've found them recommended here before, I've used them for epoxy painting my floor and I haven't explored alternatives. I'm completely open to other brands, I just don't really know better. Where does Rustoleum products rank on the spectrum of paint brands, and I assume specific product lines are better with one brand vs another brand.

Here's my experience with painting:

Air compressor stand - Built this to hold my new Kaeser SM7.5 I got last year. To paint it, I used Rustoleum "Stops Rust" Gloss Protective Enamel on top of Rustoleum "Stops Rust" primer, both in a spray can (more like half a dozen of each). What I didn't like about this was that I had to build a temporary paint booth from PVC piping and plastic sheets and questionable ventilation (I used multiple shop vacs to push and pull air, plus I used a full tyvek suit and a Sperian full-face respirator with P100 Particulate/VOC/Acid cartridges). I followed directions, mainly, cleaning material well (I actually cleaned and primed the tubing before welding). Paint stuck fine, although took longer than I expected for the paint to become relatively hard (about a week and half). I definitely have areas that aren't very smooth because of over spray from painting other areas. If I used a paint booth with better ventilation it may have helped with the over spray. All in all, the finish is fine and durable enough for it's use.

Material Rack - Built this for holding 10-12ft long bars of material. It was working out fine for several years, but I decided to add some drawers to the bottom and I figured it'd be a good time to paint it as well. I decided to go w/Rustoleum 9100 Epoxy Mastic paint because I wanted it to be durable as material will be moved on and off the rack. My first attempt involved rolling it on and brushing some areas, but it ended up having extreme orange peel which I think is due to taking too long to apply (pot life is stated to be 2-4 hours, and I painted for about 3 hours). In retrospect, I probably shouldn't have been painting beyond an hour. I ended up letting it cure and then sanding it smooth. After that, I bought an HVLP paint spray gun (Devilbiss Startingline kit), built a booth around the rack, and sprayed it in 2 coats with the gun. It was really quite a bit of work to build the temporary spray booth. I also missed/lightly coated some areas, and over spray was still a bit of a problem. The results are good enough, but I'd really like to do better next time.

My next project may be a mezzanine for my shop. Space is limited where I want to build it, and creating a paint booth around it won't be a viable option. In fact, I'll probably want to paint some parts before welding them because the mezzanine will fill a gap between my bathroom and office, and I want the edges to be close to the wall which won't leave room for a paint brush. It would be really nice to have a paint system that self levels really (even after being applied w/a paint brush). I live in San Diego, we don't have tons of humidity, but my steel structures, left uncoated, do develop a bit of rust. I only need moderate protection and durability isn't a huge concern. I would like the paint to not look like it was my first time painting.

Please advise. What type of paint do you guys use for steel structures? How many of you guys are rolling/brushing it on without seeing "tool marks" (a brush or roller is a tool, right?)? I'm open to suggestions for different types of paints, but I'm not really willing to hire the painting out to a painting contractor (that's no fun). I also don't want to move my structures to a paint booth or even the parking lot (this would require, for large structures, to move machines out of the way first). Before I get more experience (read: trying out paints w/out asking anyone), I figured I'd ask for some opinions.

Thanks,
Matt
 
Other than the overspray being everywhere I prefer using the HVLP gun. Had good results on my plasma table build using SPI epoxy primer (really good automotive type primer, dont have to topcoat it if you dont want, available in 3 colors iirc) and single stage urethane from Napa (not cheap, automotive grade, but has held up very well). This was on new steel, welded and wiped down with wax and grease remover. I have a forced air face mask and just paint when I can leave the shop for a few hours while the overspray settles. Or if weather permits, do it outside, though that tends to end up with more bits of dust etc in the finish.
 
I've not had good luck with Rustoleum products, probably because I've been using the consumer grade stuff, which are the same products you mentioned in the OP.

I now get better paint from NAPA, and for outdoor work, it has held up fine for 7-8 years so far. I did compare their lacquer to their enamel, and so far, no appreciable differences.

I just brush on; I bet there's many more options if you can spray.

We do have a big rust problem on this foggy peninsula, so I often use ZRC -- great stuff, don't need to topcoat over it either. User Guides - Applications - ZRC Worldwide
 
Although we have a paint booth and professional PPE we still are faced with much the same problems as anyone when painting. Sometimes even more because we do not have a heated air make-up system yet have to paint weekly even in damp weather. We started using this PPG product last year and so far have been pleased with the performance http://www.ppghighperformancecoatin...RD®-Rapid-Coat-DTR-Epoxy-Mastic-Coatings.aspx

Walter
 
I weld up a fair number of things for my shop. I beam style cantilever material racks, sheet metal storage and transport carts, etc. I use Rustoleum from Home Desperate and apply it with those small diameter paint rollers, almost never use a brush. I don't like the look of fabrications that are not painted. But I really don't want to waste the time for a high quality finish because I plan on using what I make and it will get scratched.
 
I use mainly Rustoleum, but I always throw some hardener in it now. Makes my life a lot easier when I can paint it one day and use it the next.
 
More details on the hardener please. Brand? Primer and topcoat? Amount?

I usually use Rustoleum on my fabrications, but the long "time to hard" can be frustrating.
 
More details on the hardener please. Brand? Primer and topcoat? Amount?

I usually use Rustoleum on my fabrications, but the long "time to hard" can be frustrating.

I use a Magic brand hardener from Tractor Supply. For amounts I do it by eye, slightly more liberal than what the label says I think. My normal paint is Rustoleum Hammer Black rolled or brushed on, if it isn't to thick it will be dry to the touch in 30min or less and hard the next day. Seems to dry glossier than without and haven't noticed any ill effects from it yet.

Everything I build is shop use items and I gave up on primer awhile ago since I'm normally behind the clock anyway and just paint two coats of color and call it good. I've also used it on the Sherwin Williams DTE enamel without a problem too. I'm sure as far as painting things properly goes, I'm doing it wrong, but it works out well for me.

Majic Catalyst Hardener, 1/2 pint - For Life Out Here
 
I haven't bought any paint from Tractor Supply since they switched from Valspar to Magic brand, but the Valspar stuff they used to sell worked quite well when used with the hardener. I've painted a number of things (air compressor stand, welding table legs, etc.) with it and it has held up quite well over the years. If you're spraying, wear a good respirator because the hardener is isocyanate-based, which can lead to some nasty health issues, especially if you get sensitized to it.

IIRC, the little half pint of hardener is supposed to treat a full gallon of paint.
 
Spraid stuff looks good, coats well, but is not durable as in resistant.
Not done 2-part spraid epoxy.

Basically, I am moving to industrial epoxies, 2 part.

For own use, painted stuff with overcoat of laquer will work well.
The laquer makes it harder, and will keep oil/shit off it.
For years.

Works really well.
Any marine laquer.

The industrial metal paints in one can, primer + paint, brushes, are ok but not great.
The laquer helps.
If I could be bothered, a finish coat from can would work.

Easier to just go 2 part epoxy.
I can afford the costs (I dont do so much).
 
I hate painting with a passion. We don't paint anymore in our shop...well, maybe the odd small job gets hit with a spray bomb but nothing big. For most jobs we just quote with no paint and let the customer look after it. Anything that does need to be coated gets sent out for powder coating. Once in a while we'll have to go with a two-part epoxy process but the powder coat shops around here can handle some pretty good sized jobs.

A well applied powder coat finish is as good as it gets and its cheap and hassle free.
 
Our paint crew painted structural steel with a 4" roller and a brush for touch up. For big areas like block walls they used a airless sprayer.
 








 
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