# Problems with a metal building



## Laz (Nov 14, 2010)

I looked at a metal building today to give an estimate on. Two problems I see. 
The first is that every screw head is rusted. The metal is fair with only a few spots of rust I would clean up and prime. What would be a recommendation on the screw heads? Use rust inhibitor/destroyer then paint? Some type of Spray bomb of Rustolium made for heavy rusted metal? A special primer with iron oxide?

The second is there is a fair size area that has tar sprayed on it. About 12x10. Not a thick coat but more like splatters from sealing blacktop nearby. It would take forever to scrape off. Don't think a pressure washer with a rotating tip would take it all off. Maybe a solvent type cleaner? I don't see any paint sticking to it or not bleeding though.


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## TJ Paint (Jun 18, 2009)

PPG has some products that can be applied DTR. There are others too. 

Solvent clean the tar.


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## CApainter (Jun 29, 2007)

Laz said:


> I looked at a metal building today to give an estimate on. Two problems I see.
> The first is that every screw head is rusted. The metal is fair with only a few spots of rust I would clean up and prime. What would be a recommendation on the screw heads? Use rust inhibitor/destroyer then paint? Some type of Spray bomb of Rustolium made for heavy rusted metal? A special primer with iron oxide?
> 
> The second is there is a fair size area that has tar sprayed on it. About 12x10. Not a thick coat but more like splatters from sealing blacktop nearby. It would take forever to scrape off. Don't think a pressure washer with a rotating tip would take it all off. Maybe a solvent type cleaner? I don't see any paint sticking to it or not bleeding though.


Question:

1. What are the dimensions of this Butler building
2. Has it been previously painted
3. Do you plan on applying a waterborne coating system
4. Is it accessible without specialized equipment
5. What does the budget and time allow on the preparation scale

If the metal siding is galvanized, there are waterborne DTM coating systems that can be used with or without a primer. There are also acrylic coating systems that include a bonding primer and are specified for existing Kynar finishes. SW Shercryl for example.

As far as preparing rusted fastener heads, ideally you would want to wire brush them before applying a brushable or sprayable rust converter, or rust inhibitor. A more aggressive and expensive approach, short of spot blasting, would be to apply a solvent borne DTR epoxy like TJ suggested. Devoe also makes a penetrating epoxy sealer (Devoe 167), but this is over kill for screw heads in my opinion unless the majority of the metal siding was also rusted, and only if the building was in a harsh environment with difficult access.

If the asphalt splatter is isolated to the lower portion of the building, and esthetics is not an issue, I would be inclined to prime over it and call it good. The problem I'd have with trying to remove the asphalt splatter is not only the time involved but the potential to create bleed through from the solvent wiping not being complete. Plus, who likes working with nasty solvents.


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## Laz (Nov 14, 2010)

Building is 80X60 by 12 ft high.
Factory painted steel vertical siding and trim like pole barn construction.
Has not been painted since it was built.
I was thinking waterborne finish.
No accessibility issues.
I was told to go look at it and give an estimate. They they said they wanted it spruced up for looks. So I imagine whatever is cheapest. Can't discus anything with them. Told they are gone for two weeks and I am to not to contact them.

I don't think doing the job right and sanding all the fasteners is feasible.
The tar goes up most of the side of the building at a corner. No idea of how it happened.


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## Laz (Nov 14, 2010)

The tar has enough build I can scrape it off with my finger nail and leaves some residue.

For the fasteners I would be telling them unless I sanded down to bare metal I would plan on them rusting again in the future. Or at least sooner. Just would like a cost effective way to treat them if they don't want to spend the money to do it right.


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## CApainter (Jun 29, 2007)

Laz said:


> The tar has enough build I can scrape it off with my finger nail and leaves some residue.
> 
> For the fasteners I would be telling them unless I sanded down to bare metal I would plan on them rusting again in the future. Or at least sooner. Just would like a cost effective way to treat them if they don't want to spend the money to do it right.


I've painted directly over rusty pipes (no mill scale) with PPG Pitt Tech waterborne DTM and haven't noticed any rust blooming. I still don't trust Waterborne's over rust though. Too bad they used a lesser dissimilar metal screw. 

At minimum, if budget doesn't allow for proper prep, a good coating buildup not to exceed the manufacturer recommended film thickness should be applied to the entire building, creating as much of a barrier as possible to prevent moisture from reaching the screw head substrate.


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## Laz (Nov 14, 2010)

So if they don't want to pay what it takes to do it right it wouldn't take to long to at least use a spray can of rust converter on the fasteners and paint the building like normal. I don't think I could just do nothing with them and spray the building.


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## CApainter (Jun 29, 2007)

Laz said:


> So if they don't want to pay what it takes to do it right it wouldn't take to long to at least use a spray can of rust converter on the fasteners and paint the building like normal. I don't think I could just do nothing with them and spray the building.


I would say that at least spot priming the screw heads with a rust converter or rust inhibitor is better then nothing, and may very well insure a longer finish coat life. It also adds to that barrier I mentioned earlier.


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## TJ Paint (Jun 18, 2009)

Sounds like they want it done cheap.

Which rules out proper prep and expensive materials.

With that parameter, I would just spot prime the fasteners with rust inhibit primer, getting a nice build and barrier like CA said. 

Scrape the loose tar, maybe do a quick orbital sand, prime that.

Then do a coat of DTM waterborne. 

You're done.


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## NACE (May 16, 2008)

I just spec'ed a building just like this. 300'x 16, two sides, and 50x30 both gables. I did specify Pre prime for the rusted dis-similar metal bolts since one gallon will cover 1200 sq ft and there is no issue going over steel and galvanized. It takes the same time to brush a bolt as it does to spray it and Pre prime is fail safe. An acrylic DTM was spec'ed as the top coat. Will not react with the tar, has rust inhibition and great color and gloss retention. This system was used on a Butler building we did 12 years ago where they refurbish 747 engines and it still looks new with no bleed through from the bolts. One catalyzed gallon of Pre prime will go a long way. Just my thoughts


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## Laz (Nov 14, 2010)

So do I have this right. The catalyzed pre prime is a DTM Product? Thanks for the advice. Looks like this will help if I can't get them to go with better prep.


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## TheRogueBristle (Mar 19, 2010)

I agree to spot prime the fasteners, then paint as normal.

For the tar, scrape of as much as you can and if you need more gas or kerosene will take it off well.


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## CApainter (Jun 29, 2007)

Laz said:


> So do I have this right. The catalyzed pre prime is a DTM Product? Thanks for the advice. Looks like this will help if I can't get them to go with better prep.


The pre prime is the Devoe 167 product I mentioned in post#3. It is a two part 100% SBV product that has certain parameters that need to be followed. Here's the link http://www.spec-tec.co.nz/altex/PrePrime1671.pdf 

I would consider this product if the siding was also rusted to a great extent. Otherwise, I'd just keep it simple with a faster drying rust inhibiting or converting primer. I know NACE won't agree with me but customer budget constraints create limited prep and paint times. You get what you pay for.

Either way, read the Pre Prime tech sheet carefully and good luck with your project.


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## NACE (May 16, 2008)

I don't disagree. I understand budgets. I believe long term that Pre prime is the best solution for the customer. No call back I'd you use 167. Potential call back with a Convertor, primer, or aerosol. I'm thinking compatibility with all the metals that are unknown. Pics would be great. NACE inspectors are very wary and we never compromise! But having been a residential painter for 15 years I honor the budget!


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