Anyone here ever painted a galvinized metal building?

[MReeb]

I've painted galvanized roofs with the roof coating made for motorhomes. It comes in 5 gal pails and has tar that drys ot an aluminum tint.

That's the stuff we used on my Grandpa's quonset building about 15 years ago. It had some serious rust spots on it (not to the point of being a hole), we brushed off the surface and went to town with the tar. We've had to redo the areas around where the bolts pop through and where the sheets overlap. I think the last time we did it was 3 or 4 years ago.
Once the stuff is on, you're pretty much commited to it. The labour to remove it would probably cost you a new building.

 

[RoyJackson]

Looking at the picture of that Quonset hut...looks like some surface rust...not too bad at all! A little clean up, and it'll be just like new

 

[IllMarty1]

Good evening, Marty --

I just noticed your post on this thread and noticed that you are a coatings inspector. I would be grateful to hear from you about the process that I did in my previous post. One thing that you mention above that I'd like clarification on is the caution about painting galvanized -- isn't it true that, on very old galvanized buildings, the fact that it's galvanized is not a huge factor because a) it is not new and b) because of the deterioration of the galvanization?

Richard,

I am assuming your building was previously coated. Your process was correct. Test patch is a excellent way to experiment with coating selection. Scratching the test area to check adhesion is also correct. Good job!

Weathered galvanized surfaces can generally be overcoated without problems, but no matter how old or weathered, I would always use a coating that is deemed ok to apply over galvanizing by the manufacturer, just to be safe.

Couple of other questions:

1. I've enclosed the jpg of the paint that I used -- are you familiar with it and, if so, how would you rate it?

2. Related to #1, this paint is around $105 per 5 gallon pail at TSC but I also checked Sherwin-Williams before purchase to see how much their Direct-to-Metal costs -- it is $250 per 5 gallon pail. Are there significant differences in materials between the two paints?

Thanks in advance . . .

Richard

Other than price, probably not much. Were they both water based acrylics? Some of these coatings have mildewcides and rust inhibitors added which can increase cost. Picture looks nice. I am guessing the coating will hold up well based on your described prep work, but whatever gloss it may have will fade quickly in that Texas sun. Congrats on a job well done!


Marty

 

[firefighter9208]

mobile home roofing is a tar like substance that is a gold color when it is first applied (I used a 6" short nap push broom -- almost a scrub brush on a long handle) but then it dries to a silver color. It's thick to apply and it's not real cheap - but it lasts for years. It's made to go on galv roofs. I used the stuff twice - both times I washed the roof down with bleach, let it dry overnight, then applied the roofing the next day. I never had to reapply - and the one I did was on an old 12 X 60 mobile from 1970 .....I recoated it in 1992 and we're still using it as a weekend place. Roof hasn't leaked yet. I never had much rust to deal with though. I'm thinking wire wheel on the loose rust, spray or paint on the rust converter of choice, then mobile home roofing or that new paint the others are talking about and you should be good to go. -- Lot of work ahead of you regardless. - have fun. ----and hurry - it's gonna get hot real soon.

Its called Kool Seal. koolseal.com: Home Works really well. You can also apply it with a deck mop.

Chris

 

[IllMarty1]

Rust Bullet Rust Prevention Products & Corrosion Inhibitor Paint Product

Above is a link I found to a product that states that you knock the loose stuff off and spray two coats several hours apart and you are good to go.

Anyone heard of this product? Kind of pricey but looks like its made for this type of application.

Warhammer

This type of coating should only be spray applied with proper personal protective equipment IMHO. PLEASE read the MSDS sheet on the link you provided. Breathing atomized vapors from this type material is dangerous.Also, if you get any of it on you, you will wear it off. Most metal pigmented polyurethanes I have worked with have very short recoat windows. I believe thats why the ad says two coats in one day. If you only get one coat on in a day, some manufacturers say you must scarify the previously applied coating befor applying second coat. It does have a use, but I personally would not use it to paint my quonset hut. I think the KISS rule applies here.

 

[warhammer]

This type of coating should only be spray applied with proper personal protective equipment IMHO. PLEASE read the MSDS sheet on the link you provided. Breathing atomized vapors from this type material is dangerous.Also, if you get any of it on you, you will wear it off. Most metal pigmented polyurethanes I have worked with have very short recoat windows. I believe thats why the ad says two coats in one day. If you only get one coat on in a day, some manufacturers say you must scarify the previously applied coating befor applying second coat. It does have a use, but I personally would not use it to paint my quonset hut. I think the KISS rule applies here.

What would you recomend for a weathered galvanized building??

Warhammer

 

[IllMarty1]

What would you recomend for a weathered galvanized building??

Warhammer

What I recommended in my first post to this thread.

 

[reasley]

Richard,

I am assuming your building was previously coated. Your process was correct. Test patch is a excellent way to experiment with coating selection. Scratching the test area to check adhesion is also correct. Good job!

Weathered galvanized surfaces can generally be overcoated without problems, but no matter how old or weathered, I would always use a coating that is deemed ok to apply over galvanizing by the manufacturer, just to be safe.



Other than price, probably not much. Were they both water based acrylics? Some of these coatings have mildewcides and rust inhibitors added which can increase cost. Picture looks nice. I am guessing the coating will hold up well based on your described prep work, but whatever gloss it may have will fade quickly in that Texas sun. Congrats on a job well done!


Marty

Good evening, Marty --

Thanks so much for the reply. I haven't viewed this thread in a while and missed your reply until today when I received one of the reminder e-mails about the thread.


Thanks so much for the compliments and the confirmation that I did OK. I thought about the building for a long time before painting!

Yes, both the paints were water-based acrylics, so it seems that the Valspar through TSC is the much better value . . .

Richard

 

[reasley]

Forgot to include a better picture that shows the finish more clearly under better light . . .

Richard

 

[MuncyBob]

I have used the Rust Bullet product on my house metal roof. The roof is a very old standing seam roof and I'm not sure of exactly what metal it is..but it is a heavy guage metal. I had rust in may areas showing up. Treated the rust areas with the Rust Bullet and a day later applied the Cool Seal roofing product mentioned. So far(3/4 of a year) I have not seen any areas where the rust has poked through. This product was suggested to me by an auto body mechanic...he used it on the frame of a 68 Camaro during restoration a few years ago and is pleased with the results(as am I so far).