I'll be painting a piece of rolling stock in the coming months once everything returns to normal. I'm currently planning on spraying, although I have minimal experience doing so, and I've budgeted to use Imron with an epoxy primer. This isn't a temporary paint job for a piece shoved in the back, this is to go on a piece of equipment that will be on display front and center. From what I've heard, Imron is real nasty stuff when sprayed, and it can be difficult to work with. I don't have a booth either, it'll be out in the open. I'm spraying because I want the best possible finish. I'm practicing using the spray gun to get some more experience before I start, but I'm wondering, does anybody have some helpful tips about Imron? How much practice should I have before attempting to spray with Imron? And, is it really worth spraying to try and get that nice finish, or with my experience, would I be better off rolling? I'm looking to do as good a job as possible, feedback from those who have used this product before would be appreciated. Thank you.

Consult with experts. Period.
T7

If you absolutely must use it, make sure you talk to an experienced automotive painter and get some education on how to handle it safely. It's one of the most dangerous paints ever made. It can kill you if you mix and wear improper safety equipment when spraying. You need a continuously supplied fresh air breathing system with proper fume collection just for starters.

I purchased some a year ago and ended up selling it to another railroad after I realized it was too dangerous for our volunteer workers to work with.

I'm only aware of two pieces of equipment being rolled with Imron. One was a locomotive with a orange peel texture. The coach came out the same.

Imron does a fantastic job and it lasts and last, but it is wicked stuff. I painted our NYC Pullman sleeper with it almost 20 years ago now. Even though I wore gloves I got some on my hands. It ate my skin. It took weeks to heal. If you use it you MUST wear gloves, paper coveralls with a hood and most importantly a mask with a separate air supply. Even though I was very happy with the results I wouldn't use it again for the reasons above.
On projects since I've used PPG Delfleet Evolution. It also does a nice job, but is not as dangerous. I still wouldn't snort the stuff though. ;)

Let me start with the fact that I haven't been painting in about a decade, and locomotives for almost two decades--I was much younger then! But FIRST: Wear the protective equipment, IMRON and the suitable primers have some really nasty chemicals in them. I painted locomotives for the Portola Railroad museum, and some of the time it was in the outdoors Probably the most famous one is WP805A. You do want 1) NO wind, 2) almost NO dust; the climate at Portola, until the late afternoon usually fit those two requirements. Generally speaking, work from the top down; you don't want to put overspray on your nicely finished sides when you do the cab roof!
These paints are expensive--nowadays I would say VERY expensive, so you want to reduce waste, we did that buy buying a turbine HVLP system. As I recall, the system was about $800 (20 years ago) and it paid for itself on the first paint job, as we used about half of what would have been needed using a regular (for the time) spray gun, so there was at least $800 savings on materials. Locomotives take a LOT of paint, so I used a 2 quart pressure pot system.
To keep dust down, you can water the ground and areas around the painting area. Fortunately Locomotives, other then the pilots and steps, are already pretty high off the ground, so that helps a LOT. The HVLP system had so little overspray, I could usually paint the trucks without any masking.
DO practice a LOT! The paint is expensive! Mistakes happen, and fixing them can be done. . .with time.
Be aware that if you do a whole body in one color, you will be painting a long time, and outdoors, or under a canopy, the temperature will be changing from morning to day to afternoon. When I painted the main body of WP2001 I was painting all day, and changed reducer temperatures at least 3 times, so have a variety of reducers on hand before you start. While the primers go on easier than the color coats, you do want the primers to be smooth, especially the ones that don't require sanding before color coating (like the epoxy primers such as the Ditzler DP series).
When I did these jobs I would prime bare & sanded painted metal with DP primer, do any "bondo" body work, or high-build primer-surfacer, and then seal it with another coat of DP.
PLAN your painting. Where are you going to start & stop; Cab corners are a good edge for this, start by giving the ending corner a light coat so when you come around to it again, you can direct the spray out away from the already painted (and drying) side, yet have full coverage on the corner edge.
Pay attention to the mills of finish you are applying, the manufacturer's recommendations are best, don't go too thin, but don't go too thick either. As I recall, 1.5 mills was "ideal." 2 mills would probably be OK, but 2.5 mills likely will cause problems down the road. Also, when I did the 2001, we painted the lettering black on first, then (after some curing time) masked it with self-adhesive lettering masks (cut by a computer!) Then applied the color coat; this way the lettering was slightly recessed, and would not be worn off over the years. Also plan what colors to put on first and last, in the case of the 2001, I recall we did the roof (black) then the silver sides, upper and lower, and finally the Orange. Silver has a hard time hiding what is below it, and reds (orange is a variation on it) tend to bleed through. On 805A the red feather was put on last, and the white striping first (even before the orange body as I recall. Hmm I have pictures--somewhere. . . . That was a long time ago, I am surprised I remember this much!
Now I will admit, the color coats were Centari, not Imron, which does spray slightly differently. The flow out is different, and you will have to play with it to learn it. Fortunately trains are LARGE objects, they didn't originally come with "20 feet deep" smooth finishes, some "orange peel" is acceptable. Don't go too much with your first color coat, it is the " setting" coat that the next coat grabs onto (and be careful how long a time between the set coat and the final coat; you sorta have to work your way around the engine. How do I explain this? Go so far with your first set coat until the time is right for where you started the set coat, and go back and do the final coat up to about where you stopped the set coat, continue with the set coat, and go back and blend in the top coat where you stopped--as long as your timing is good, the paint will flow together, especially if you can do it where panels end or a corner, even if it's a rounded corner. With metallic finishes, like the silver, you have to be really careful to keep the paint agitated (some marbles in the paint can help) so the metallic particles are in suspension--and you can't let it flow out too much or the metallic particles start to run in the finish.
I hope I haven't scared you off, as it really is a rewarding thing to do when it all goes right. We won't talk about the other possibility. . .
Here's a picture of a much smaller object, but one with lots of problem surfaces. This finish is Concept, somewhat very akin to Imron. Flow out on this was helped by cool weather, and I could turn the wheel to stop runs--can't do that with a locomotive!


I found some pics I took in 2017 of 805A and 2001, mind you I painted these in the 1990s, so they have weathered some, but the finish is (I think) still good.

And a close up of the "wing"


And now the 2001, undergoing some servicing at the time; note the front outside corner of the cab, that was my "start-stop" point, also note the curves on the nose; those were good places to "blend the "going around" first coat and top coat. (is this clear as mud??


And as for painting outside, this B unit was prepped and painted outside.

I'm reading some really good stuff that has shown up since I was writing this and hate to bump them down - please read with their emphasis on safety as well as some great tips.

A lot depends on what VOC you are shooting and for what application. I'll assume RR stuff. Working from memory, the old Imron (early 2000's) was 333 which I think became 3.5HG. There is also a 2.1 HG. I shot 50 gals of one of those in black on UP 4023. Smaller areas with a gravity gun with 1.8mm or 2.2mm tips depending on outside temp and how big because if you go big and want to blend it you have to go fast. For very large areas 2 of us (John Rimmasch and I) would go down both sides of RR equip together with a paint pot and a helper/spotter each. Don't remember that tip size. The 4023 and UPP 814 were both prepped with an acid etch and Nason SelectPrime2K, which was sanded to 220. Some epoxy primers seem to stay sticky and some get so hard they are un-sandable. I was paying some attention to what the painter was doing on N&W 611 when I was there and this was Axalta with the clearcoat, which a lot of people prefer, but I don't as it is harder to spot touch up. There is a roller additive which helps it not pinhole, and you can get good results with a very good roller that does not come apart with very sticky paint. If you are going over anything that might be oily, there is also an anti-fish eye.

I bought an ancient DeVilbiss paint pot and have never used it - I quit shooting with the industrial Imron more than 10 years ago. Instead, I build-up rough parts (like cast) with Sherwin-Williams PolaneSprayFil and sticking with Nason2K primer and Ful-Thane 2K Urethane top - which is actually what all the other colors are on 4023 are less the rods, which are a Centari mix of pure metallic. Not sure how that thing looks now - never went back to see it - but I have painted a number of cars, steam engines (not locomotives) and industrial things with Nason. I think the thinner topcoat holds better, but requires more prep materials and labor.

The fact is it just takes some years and gallons to become a good painter and many good painters die of cancer. I started early repainting the back of tow trucks after every winter season in High School, painted my first car (a military Jeep) at 16 and have painted a number of cars, trucks, tractor trucks, railcars, locomotives, equipment, and steam engines - even Jukebox parts. Today, I almost never paint, weld very little, don't use Brakekleen - esp. chlorinated. Seen to many people die from that stuff and none of it is worth it. I would not do a spray paint job today without fresh breathing air and Tyvek suit.

Short answer is consider rolling it yourself, otherwise hire a professional contractor. You can build a functional booth out of poly on the outside of scaffolding and proper air handling and filtration. Paint is one of those amazingly deadly toxic things that the public can buy but really shouldn't be able to without knowing the risks to oneself and others from mishandling/misapplication.

In looking back over my post, and the other posts, I may have not emphasized the importance of safety equipment enough. The equipment (except for the breathing equipment is relatively inexpensive (and I am more than frugal, I am CHEAP!) and worth every cent you spend on it--if you USE it. The other nice thing, is at the end of the day, you take it all off, and you don't smell like paint, you won't be chased out of the house!
I became a museum curator so I could get away from the chemicals, after some 30+ years restoring cars & trains I figured I needed to get away from it all. Now it is just (once again) my hobby and if I can finish the insides of this house before summer, maybe I can go back to working on my Model Ts.
Also, it sounds like you are doing a railroad car. The nice thing about rr cars is they are mostly single flat surfaces, and they have four corners, so you can do a bit at a time. In fact, one side can be a different color than the other side and very few people will ever notice! :) So, you can deal with it in smaller bites. However, they often have lots of "panels" with battens between. Note that paint does not spray around corners, even ones that are only 1/4" deep, you do have to direct the paint into those corners--sometimes you start out by putting some color on those areas first before painting the panels.
Good luck!

ajb3243 - Welcome to the Interchange.

While Imron and other similar urethane coatings are great, long-lasting industrial/marine coatings, there are other things to consider. Are you required to use a spray booth with filtration and air supply? Some states regulate it due to environmental and health hazards.

Urethanes are very toxic. Axalta, PPG, Sherwin-Williams, etc. have other coatings that are long lasting and aren’t as dangerous to apply. I’d suggest talking to their Industrial Coatings reps before you decide what you’re going to use and how to apply it.

You didn’t say what you were going to paint. That is a factor to consider when determining the type of paint to use. Some are designed to seal over fixed rust or flash rust, most need commercial blast or better surface prep to last the longest. You might want to consider something along the lines of an epoxy primer and acrylic top coat. There are other choices, also. I’ve seen pretty good results with automotive coatings.

A good paint job is all about surface prep. Follow the coating manufacturer’s procedures exactly. Expect that any rust remaining will eventually propagate. Hence, the reason for looking at less expensive alternatives that can be easily touched up. The surface must be clean and dust free. Don’t touch it once it’s clean or primed or finger prints will affect adhesion.

Outdoor application will depend on the weather i.e. wind, temperature, humidity, cloud cover (no direct sun), etc. don’t expect to paint it all in one shot with one mix ratio unless you’re very lucky. Outdoor painting requires additional planning.

There is a learning curve with spraying. Different products, different make-up equals different curves and different equipment. I’d suggest hiring a painter familiar with the product chosen. It’s too expensive to practice with urethanes and a poor application of any coating will be a waste of money.

My two cents....

Probably a good idea is to learn, or at least try to learn (or have someone who knows organic chem explain to you in English) just why epoxides are as dangerous as they are. Even in very small quantities in the human lung, or on human skin or mucous membranes.

1) this will prevent you from doing 'feel-good' self-protection or using cheaper PPE with the idea 'it said it would work on the package', and

2) you will have better understanding of how the stuff works, and why some of the stuff that is presented as 'black magic' is done the way it's recommended -- reducer being one such.

Note that you can buy handheld meters fairly cheap that can give you a remote-from-your-body reading of film thickness. If you do any work with Imron get one of these; learn to use it; learn not to contaminate it with casual contact or overspray "in the field". Learn to use these to control your thickness; it probably makes sense to have someone else taking frequent measurements as the 'painter' is working, and keep at least a rudimentary log of where thin sections might want another coat...

Note also that if you sand this between coats, the dust is also a toxic hazard, and needs to be carefully dealt with (e.g. through vacuum ports and pickups, and careful wiping or tack-rags used with full disposable-overglove-and-PPE care) at all times. People forget and think that when the paint is cured it becomes chemically inert because it's crosslinked to resist the environment. That's true in a film but look at the surface area in the dust you've generated...

I don't see a technical reason why Imron could not be thinned to be self-leveling when rolled out -- but this is going to require sensible experimentation by (relatively well-heeled) people in the preservation industry. Choice of roller material and surface are going to be critical, as there is a fine limit between too thin a cured film and too saggy and runny a cured film, and improper coverage with the likely effect of bull's-eyes and a thickly orange-peeled surface. There is a long history of getting effective self-leveling with 'plastic' acrylic-based paints -- that simply hasn't happened with kilodollar-per-job epoxies yet. This community is clearly one of the places the experimentation, on a proper scientific basis intended among other things to permit full reproduceable results, could and should be conducted...

Yes. A thousand times yes.

While I am not a painter, I've seen several what should have been excellent paintjobs go to hell PDQ due to improper preparation and planning.

One of our cars had its interior painted on a sunny summer day just before a storm moved in. The surface's temperature would have changed by more than 20 degrees before the paint finished curing, and as a result it started peeling within weeks. We ended up having to redo everything.

Another one was sandblasted before painting, but did not get down to bare metal everywhere. The new paint adhered perfectly, but the oldest underlying paint layer is now separating from the metal, and it is now peeling in some areas.

Thanks to everyone who has responded so far. You’ve given me a lot to work it. I should have mentioned, I’ll be painting just a caboose in one color with only two small windows on each side, so I’ll be just about uninterrupted by features when painting. I don’t have the budget to do any type of blasting, but my team and I will be using orbital sanders to take a lot of the paint off. We’ll be doing our best to remove as much old paint as possible. I believe there’s only paint from the last paint job left, primer and what little remains of a topcoat. I know the amazing Benjamin Moore rust converter that takes care of rust for your life span is no longer manufactured, are there any other rust converts that work almost as well? I’ve heard recommendations to put converter down before a primer, to give even more longevity to the primer and topcoat. Thoughts on that?


David,

Thanks for the response, you gave me a lot to think about. The units look superb for being painted in the 90s. I’ve heard of recessing the lettering first to reduce wear, and I was considering doing that. Removing the masking over the letters, however, that requires cutting very, very gently through the paint around it, right? How much work is it compared to normal lettering, and is the reduced wear worth doing it like that?

mjanssen,

Thanks for the response. I looked up the Nason SelectPrime2K, and I see that it’s a urethane primer. I’ve had recommendations for using an epoxy primer instead of urethane; you mentioned epoxy primers can get sticky and unsandable. Is that why you recommend the urethane over the epoxy? Is there a major difference in lifespan between the two, providing I have the proper surface prep? And, can the Nason SelectPrime2K be applied over surfaces that aren’t bare metal?

The rust converters are important because they get into any small grain areas of corrosion, including 'pinholing' through metal sheets, and either arrest or passivate them. This will preclude debonding of the primer layer later, which can be progressive in a number of situations even with good 'paint film' strength.

Note that other methods of surface prep other than 'tangential' grinding or sanding may remove more of this kind of corrosion -- notably needle-gunning or sharp-media (not so much 'bead') blasting. I don't have firsthand experience with high-velocity "dry ice" blasting, from the standpoint of full surface-corrosion elimination from pits and 'nooks and crannies', and I'd be interested to hear from those here who do have that experience, or know people who do.

In my opinion, the type of 'converter' that used to be sold to go straight onto a rusty surface with minimal cleaning/grinding is less desirable for epoxy-paint overcoating, as the phosphated or whatever mass has limited tensile strength (although it has essentially been passivated throughout). It doesn't really help if the zone behind a peel 'bubble' is not likely to further rust with water exposure...

RE: rust converter, we've had good results using this stuff:

http://www.corroseal.com/

In fact, we just had the interior of our steam locomotive's tender water tank coated, and the contractor used it as primer. Said they've been using it for years.

I should note, our tender job still required a large amount of prep work to remove the large flakes and deeper layers of rust Overmod mentions. And I don't think we have ever painted over this stuff with an epoxy paint, we normally use a oil-base marine enamel for most jobs, due to the 'amateur' skill level of most of our volunteers (including myself).

Mop and broom paint jobs can be just fine. The Sheboygan interurban car at the East Troy RR Museum was professionally restored and using the techniques of the era (1908) was painted with oil based enamel using a roller and brush. Spraying painting the vertical poplar siding boards below the belt line would have created many opportunities for paint runs. The car has been in operational use since 2005 and still looks just fine.

https://www.easttroyrr.org/roster---car-26.html

SD70dude,

Have you used it just as a primer on other projects and then top-coated, or have you used primers on top of it?