# What Paint to use on new steel bridge?



## Bob Lessig (Jan 3, 2008)

All:

I have watched several of you guys build steel bridges over the years and I have finally started building my steel bridges. I am building five, ten foot long, thru warren truss bridges that will span a 50' area over my leach field. I have the bridge sides done for one of the bridges. I wanted to build one bridge first to see how much trouble it was going to be to build them. I am also learning how to weld at the same time. I hope to post pictures as this project progresses.










I just had to try and post a picture, hope it works!

Now to the meat of the post. What have you guys that have build steel bridges in the past used to paint them? I remember that Marty said that he used an agricultural machinery primer before painting his. Has any one else used a primer before the final coat and what kind of primer did you use and what do you think of it?

Now, what kind of paint did you use for the final coat? I was thinking that if these bridges are going to sit outside year round that you would have to use a pretty good paint with excellent UV protectant. I was thinking that I was going to have to use an automotive paint but after checking on the cost, it was going to be about about $300 to $400 per gallon. It looks like that the way these bridges are build that you are going to get a lot of spray through and using a lot of paint. I wanted to paint my bridges a light green instead of black or silver. That means that I am going to have to get a custom color blend.

Do rattle can spray paints work? Do they last outside? What are the rest of you using?

Any help with painting these beast would be appriciated.

Bob Lessig
UP & Western


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## Paul Burch (Jan 2, 2008)

I have always used Rustoleum, both for primer and finish,without problems. Rattle cans would probably be pretty wastefull for a project this big.


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## Bob Lessig (Jan 3, 2008)

Paul:

I am assuming that you can buy rustolium by the pint or larger. Doesn't it come in rattles cans also?


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## Totalwrecker (Feb 26, 2009)

Quick reply; yes it's in spray cans too. 
Paul noted though; that much will be lost in over spray...just not in so many words. 

Look into having them sand/media blasted first, that will help the paint last longer. 

Oh, that's a nice looking truss, looks like your skills are up to the job! Congratulation!

John


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## Bob Lessig (Jan 3, 2008)

I have had friends tell me to look into powder coating them. I know that they will sand blast them before they powder coat. I have also talked to guys that have had powder coated bridges and the powder coating is starting to fail. If I painted them I think it would be easier to touch up the bad areas. I guess you can't do that with powder coating.


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## Daniel Peck (Mar 31, 2009)

I use powder coating... but I have got a cost on hot dip gavanized coating which is much cheaper if you want the silver color. $250 bucks for up to 500 lbs of metal.... not a bad price.


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## armorsmith (Jun 1, 2008)

The only caveat to galvanizing is that in the coating process the heat of the hot dipping can twist and warp a structure. If this happens it can be real difficult to get it back to straight again, especially with the small cross section material we use. 

Good luck! 

Bob C.


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## Daniel Peck (Mar 31, 2009)

Hot dip galvanizing gives user benefits no other coating system can match: 

â€¢ Unbroken protection barrier â€" the work piece is completely covered. Galvanizing coats areas inaccessible to brush or spray applied coatings. 

â€¢ Thicker coating on corners and edges â€" extra protection for critical areas. 

â€¢ Impact and abrasion resistance â€" metallurgical bond of zinc to steel provides four layers of zinc and zinc-iron alloys. This results in great toughness. 

â€¢ Coating is anodic to base metal â€" cathodic action allows zinc coating to sacrifice itself to protect exposed steel. Cut edges, drill holes or abrasion an impact areas remain rust free. Coating thickness is controlled by the thickness of the steel. A standard minimum thickness results. 

â€¢ Predictable length of life â€" can be charted for varying environments. 




Quality Assurance 

At GALVAN, surface preparation, fluxing and galvanizing are performed in the sequence shown in the chart below. This process consistently produces high quality galvanizing coatings to the most exacting customer specifications. 

All products pass our in-house Quality Control and Assurance Program to insure that the coating is in compliance with specifications. Our work conforms to ASTM, AASHTO, or Mill Specs. Certifications provided upon request. 

GALVAN is a member of the American Hot Dip Galvanizers Association and is involved in developing industry-wide standards for galvanizing quality. 





The Galvanizing Process 

Material to be coated is immersed in a kettle of molten zinc at a temperature of 850Â°F. The time of immersion in the galvanizing bath varies with the dimensions and chemistry of the materials being coated. Materials with thick sections take a longer time to galvanize than those with thin sections. 

Small articles like nails, fittings, screws, nuts and washers are cleaned, placed in a perforated basket and immersed in the zinc bath. The basket is then centrifuged to remove excess zinc. This spinning action eliminates droplets and irregularities, producing a somewhat thinner and more uniform finish than individual dipping. 



Final surface appearance and coating thickness are controlled by four factors: immersion time and/or bath temperature; rate of withdrawal from bath; removal of excess zinc by wiping, shaking or centrifuging; control of cooling rate in water quenching or air cooling. 
http://www.galvan-ize.com/galvanizing-benefits.asp 

850 degrees is not that hot and dipped all at once evenly should not twist. I ask the people personaly and shold them one of my bridges, they said they could dip them with out a problem.


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## livesteam53 (Jan 4, 2008)

I used to primer them and then color them with Rustoleum. It holds up pretty good. 
Now I have everything powder coated. This holds up real well. 
Sand them first real good weather you using the Rustoleum or powder coat. It has to be clean.


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## aceinspp (Jan 2, 2008)

If it were me I'd powder coat the bridge and have a nice finish that will last. later RJD


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## Jerry Barnes (Jan 2, 2008)

I used Krylon primer and topcoat.


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## John J (Dec 29, 2007)

That is one beautiful bridge.

Paint?

I leave them natural

But if you insist Black first......Rusty ornange second


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## denray (Jan 5, 2008)

Bob
Great looking bridge parts, never paint without using a good primer first, primer is designed to bond to bare metal, and paint is designed to adhere to the primer, Rustoleum paint in the rattle cans are great for this type of coverage, using primer first, i have used a color that is close to rust, so when it gets a little rust on it you do not really see it. Besides touch up with paint is easier. You can touch up powder coat with the right paint, it does not look the same but it can be done, powder coat is more expensive, but it is about 10 times more durable. 



















closer up uf the paint color

having fun
Dennis


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## Biblegrove RR (Jan 4, 2008)

Zinc eh? I planned to have mine done in powder coat and think they can any color imaginable? What exactly is that Government color shade of puke green that look sso nice on bridges etc.? Anybody got that info?


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## Bob Lessig (Jan 3, 2008)

I call that color "Light Green". The Light Green that I would like to match is the same as Floquil "Light Green". That is the color that I use to paint the cab interiors of my diesels. It is about the same color as the guy's shirt in the previous picture.

I did check the Rustolium website and found out that you are limited to the colors that they already have, no custom mixing. Dang! I may have to go with just Black. Those of you that have used the Rustolium paints, are they high gloss or semi gloss? I would think that you would not want a high gloss bridge. Maybe they dull pretty fast in the sun.


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## Bob Lessig (Jan 3, 2008)

Well, since it was cold and raining outside today, I figured that I could get my bridge welded together today. Here are the results. I still need to finish each weld and grind them flat. Once I am at that point I can add the details.



















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## John J (Dec 29, 2007)

Wow your bridges is as beautiful as the backdrop


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## Richard Weatherby (Jan 3, 2008)

First, I must say that I have never built a welded metal bridge. Now for what I know about galvanizing. Galvanizing is only as good as the prep and thickness of galvanizing. I have seen miles and miles of rusty galvanized chain link fence. As for hot dipping, you REALLY need to understand the issues of shapes and provide vent holes for tubular or cylindical shapes. The trapped air can cause extreme pressure in the hot molten zinc. 

If I were to do it, I would abrasive blast to "White." Apply an industrial enamel primer and then a high end ureathane paint. These all should be available in a local brand name paint store. 

I was going to attach a link to SSPC, but it seems that you need to purchase standards in order to find out what it says. This organization along with NACE (National Association of Corrosive Engineers) and AASHTO are the groups that set standards for real bridges. 

I am sure this is way more than anyone wanted to know, but there are good methods and paint products available. 

If you put that much work into it, do your best to protect it.


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## fsfazekas (Feb 19, 2008)

Hi Bob,

Is there a forum thread documenting your experiences learning to weld, equipment selection and construction of the bridge? I'm in the same situation where welding is a skill I need to tackle. I thought it might be helpful to get some insight from someone that's just gone through the process.


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## Bob Lessig (Jan 3, 2008)

Frank:

Sorry, this is the only thread that I have stated about these bridges. I was worried that these things were going to cost me more to paint than what it is going to cost me to build them. Right now I figure that each bridge has approximately $100.00 of steel in them. I figure that is not a bad price for the size of these things. 10' long by 27 1/2" high.

I was lucky enough to be able to borrow a Hobart "Handler 140" wire feed welder. It was my wife's uncle's welder. He welded for the aerospace industry for a living. He had given it to his son and grandson and surprised me by bringing it up to my house one day and told me to use it. That was about a year and a half ago. I finally got around to designing the bridges and buying the steel last fall. I needed to build a table to assemble them on and I got around to building one the first of the year. Now the grandson is graduating from a community collage and wants to take the welder to California and hopefully find a job. Now I won't have a welder to finish the other 4 bridges. I looked online today and check the prices of a Hobart "Handler 140" and the cheapest that I found was about $532.00 w/stand. Retail is about $690.00 w/stand. I will probably buy one.

I know how you feel about starting to weld. It sounds a little intimidating to start. I just started playing with it one day on some scrap metal and found it to be not that intimidating. I was lucky enough to have this grandson going to school just 20 miles away, so I got him to come over and give me some tips. I forgot 1/2 of what he told me and just started welding. I felt that I did pretty good on the butt welds on the sides of the bridges, but when I tried to do the fillets, they looked terrible. So, I called him up and asked him to come over again sometime to help me with those welds. I was also having trouble with burn through. He finally showed up and he told me a couple of tips that really helped and I was able to get the fillets welded so that they did not look to bad. They were not great but they were acceptable. I finished up both sides and just plowed ahead with putting the cross members in and before you know it, you have a bridge.

I did not use gas with the welder. I just used flux core wire. My wife's uncle had .035" wire in the machine already, so I just used that. I found that without gas you get a lot of splatter, so you have to clean up the welds. I am just to particular to leave them as they are, so I am using a grinder to get the butt welds flat and cleaned up. This grandson did tell me about flap sanders that you can get for your grinder and they come in different grits, so you can clean up the grinding pretty good. They actually come out real smooth.

I designed the bridges by scaling up an example of a 200' Warren Truss bridge that I found in Kalmbach's "Model Railroad Bridges & Trestles" book that I had bought several years ago when I was doing HO. My bridges scale out to 290' for 1:29th. The example gave dimensions for height and I just used 1' increments for the risers. I just tried to keep that same proportions of the example bridge in the book.

I used Cadrail to draw the bridges and then I would print out each of the joints at 1:1, then take a protractor and get the angle of the pieces so I would know how to grind them. I used a Craftsman sanding station with an 8" round sanding drum with a miter gauge to grind the angles on each piece. The bridge is made from 1/2" square tubing, 16 gauge mild steel. The sanding station works great for this. I just use a steel blade on a chop saw to cut the pieces to the approximate length and finish them on the sander.

As far as learning to weld, I say just go for it. If you look around on the web, there are several sites that actually have videos of learning how to weld.

I hope that this helped you some. If you have any other questions, I will surely try and answer them, as far as my experiences with welding go because I am by no means an expert welder. I feel that I was able to build a project that looks like it will hold up for the rest of my lifetime and looks acceptable and I am happy with the results. I know where the mistakes are on these bridges but you will soon forget about them and they will look just great to everyone else that sees them. Once you stand back and look at what you have accomplished, you will be impressed by there size and look. I can't wait to run trains through them.


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## H-man (Jan 4, 2008)

Bob, 

Very nice. I'm having about the same experience and just jumped in with a rather basic wire feed welder. this summer I plan on starting one of the 8 bridhes planned for my layout. Have one about the same size as yours. 

Howard


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## Bob Lessig (Jan 3, 2008)

I just remembered a question that I have forgotten to ask. It sounds like Rustolium paint is going to be my best bet. They have the primer and they have the final coat. They only thing is that Rustolium only comes in premixed colors. If that is the case, I will have to go with just black bridges. That is fine, but I would really like a light green. The question is, it looks like Rustolium comes only in High Gloss. Is that the paint finish that everyone else is using? I would think that a Semi Gloss or Flat paint finish would be better. What does everyone else use, Gloss, Semi Gloss or Flat paint?

Will High Gloss flatten out as it weathers in the sun?


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## fsfazekas (Feb 19, 2008)

Bob, 

Thank you for your earlier post. I appreciate you taking the time to relate your experience. I'm just gathering information at the moment though hoping to jump in to welding a little later this year. Regarding your paint issue - I know Rustoleum makes a good primer in their "rusty metal primer" as my Dad and I used it on a '68 Mustang we restored during my high school years. However, once primed, wouldn't you be able to use a different manufacturer's product for the top / color coat?


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## Bob Lessig (Jan 3, 2008)

Here are a couple of pictures of the bridge with details added. This one is done and ready for paint. I have decided to use Rust-Oleum Professional High Performance Metal Primer and Professional High Performance Protective Enamel. I think that I will go with a Semi-Gloss Black over a Flat Black. What kind of paint sprayer would be a good one to use spraying enamel? I was thinking of getting one of those automotive type sprayers with what looks like about a pint or maybe a quart container. If anyone has used Rust-Oleum paint, does it have to be thinned?


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