All,
I am working with a group of volunteers to restore former reading company coach 1341 back into service on the Stewartstown Railroad. I started painting the exterior this past weekend. When I came back 2 days later, white cloudy patches started appearing thru the paint. While I do not know the exact series of paint, I do know that it's an oil-based industrial enamel from Sherwin Williams. Any idea on what may have happened?

This is just a guess, without knowing the specifics of the paint, the solvent in the top coat caused the primer to bleed into the top coat. I saw this once before where the primer was latex based and the top coat was an alkyd enamel.

Mike Tillger

Hello... Having work for SW for many years I would first suggest you travel back to your SW store where you purchase your IE. Tell the Store Mgr your problem and if he does not have the answer ask him to send out a sales rep for an educated answer. I have an idea that it is moisture trapped underneath the film or a reaction with your primer. Was it a damp day or rainy before or after? It is possible that when that area dries that will disappear. DID you wipe down the surface with xylene before painting? DO NOT use mineral spirits. That is a oily product. Surface must be as clean as possible and do not use the same dirty rag. You are just spreading the contaminants if you do. We have been using this technique for years at the Illinois Railway Museum and never had a major paint failure. Go back to your dealer is my suggestion to you. I am sure he will be able to answer you questions. And be sure and get a discount!! Enjoy painting. Roger Kramer

Mike, The primer below was rustoleum rusty metal primer.

Rustoleum Rusty Metal Primer.

This stuff, once known as #769 Damp-Proof Primer, was once the go-to stuff for restoration folks. 769 could be applied in small sections as a project progressed, and then topcoated when ready for the final finish colors, and it worked well. It seems that re-formulations over the last few decades have made Rustoleum Red Primer into a rather troublesome product.

At Railroad Museum of New England, we have had two freight cars that were painted about 2001-2003 with RMP and then top-coated with Rustoleum Black, start to shed the black topcoat a few years after the painting was completed. In one case, a PRR H-39 hopper car, the black topcoat was applied just two weeks after the prime coat (which was done in one day). 5 years later, the black started to peel, and is now probably 75% failed/peeled off.

After that, and a GATX tank car had similar problems after the same painting protocol, we stopped using RMP for any area that would be exposed and top coated with the finished exterior paint.

Recent paint projects done at RMNE were two CNR coaches and one B&M steel boxcar. The first CNR coach, done in fall of 2012, was primed with S-W High-Solids Industrial Primer and topcoated with custom-mixed (to CNR green and yellow) industrial alkyd enamel. The next CNR coach to be painted was painted with the same S-W system.

The recent B&M boxcar was done in Benjamin Moore paints and I think it was a much nicer paint to apply-- flowed out beautifully.

I think it's critical to use a compatible system of primer and topcoat, ideally both made by the same manufacturer. If the surface is properly prepared-- sanded to an old well-adhering top coat, and any surface rust is sanded to clean metal (or best of all, grit/sand blasted), there is no need for "rusty metal" primer.

"Rusty metal primer" cannot simply be slapped over rust and then topcoated.

That light area on the green carside looks to me like moisture/humidity "blushing" under the top coat. I have seen that, when paint is applied on a damp surface or on a steel car/humid day scenario.

Get your S-W rep out there, as Roger Kramer suggested. Good luck and let us know what happens!

Howard P.

Wha time of day did you paint it? How much did you thin the topcoat? Paint too late in the afternoon, and evening dew can get on the paint before it dries.

It was painted around 6 PM on a Sunny Day. The paint was not thinned.

Was this a roller and brush job, or sprayed? Spray painting yields a thinner paint film thickness (usually). The thicker film of roller or brush takes longer to dry and for the solvent sin the paint to flash off.

When painting outside, especially with roller and/or brush, you want to start early enough so the car's metal is warm and continues to be so throughout the day's painting. Painting at 6 pm is rather late in the day, to insure good drying and solvent flash-off before the car's surface cools off.

I'm thinking that light-colored blushing is moisture affecting the drying and stratification in the paint film, and is the result of late-in-the-day painting.

Paint early enough so that the sun gets the car and the paint warm. That will help tremendously when painting outside.

Howard P.

Bingo! Unless you have experience with this particular paint to the contrary, alkyds are notoriously slow to dry. I've had unreduced alkyds still sticky after 10 hours. Reducing (using thinner) hastens dry time, as does using Japan Dryer, which seems to be scarce anymore. [exception: Awlgrip 545 primer takes longer to dry when reduced. That is becuase the default solvents flash faster than the recommended brush reducer.]

So why did it splotch? Because in the splotched area, something is different in one of two ways. Most likely it had different thermal properties, and cooled at a different rate, causing the dew to strike differently there; or something about that area affected the rate at which the paint dried - due to porosity, chemical considerations (e.g. primer that was thicker there and so wasn't quite dry), or again something thermal like bondo or rust, insulating the paint from the car's latent heat, so causing it to dry slower.)

The paint has been deglossed. Instead of a mirror smooth surface required for gloss, it is mottled or chemically damaged.

I would say get light steel wool or scotch pad and scuff-sand the affected area. Not sandpaper, you don't want to "burn through" the topcoat and primer, or you'll have to start over with the primer. If the stuff sands off easily, it is damaged - take it all off and start over. If the surface seems relatively solid, then lay your second coat over it.

I generally plan my painting so I am done by about 3pm. In a perfect world, I wipe the morning dew off with a towel and am painting an hour later. Yeah, right!

You definitely need to start painting earlier in the day. 6PM is way to late to paint with oil based air dry enamel such as Rustoleum. Without a doubt the moisture from the late afternoon/evening penetrated into the top coat and caused this. It has happened to our group a few times painting cars and locomotives with air dry enamel and we ended up with the same cloudy white areas. Luckily the paint didn't start to weep or get fish eyes. We've had that happen as well.

You want to wait for a non humid 70+ degree day and start painting as early as possible. I found that if I spray (or roll) around 10-11AM after the morning dew is gone, the panel will have all day to dry to the touch (not cure). By the time the late afternoon comes, the top coat will be dry enough where moisture won't bother it.

Good luck with your projects!

Putting on painting contractor's hat ...

The comment to ask SW is good. Just keep in mind that you really want one of SW's industrial reps. There's only a few of them around. Your typical store manager ends up looking things up on the SW database. Most of the reps deal with commercial jobs.

Especially today, everyone wants a "green" paint. That means water-based. Somehow the idea of putting water on steel never seemed to make much sense to me. There are still oil-based products out there -- they are harder to apply and get. For example, some states will not permit the sale of paint with a high VOC limit. PA is one. Ran into this a couple years ago. The high VOC stuff tends to last longer IMHO. Yes, you have to clean with solvents and use respirators.

Consider finding yourself a really good painter to work with you. Everyone thinks they can paint -- there's more to it than you think. Plus, bigger commercial painters (and I'm talking at least $1 million a year in work) get a MUCH cheaper price from SW than you will. My company has worked with non-profits in the past. We'll order the paint at our price -- it's at least 50% less than what SW even quotes to a non-profit. We aren't looking to make any money on the materials, but it helps keep our paint volume purchases up.

There's a company out there called Tnemec. They make really high end coatings (think painting water towers). Their material is in the $400 a gallon range, but it lasts forever. If you do things like water towers, you don't want to have to paint every couple years. They have some really good tech reps that can guide you with the correct system.

Just a quick note on SW. For the caboose I helped with, I called SW directly and spoke to an industrial rep. Very, very helpful. I was provided all the specs on the primer and the top coat, essentially doing it as a system. I then went to the local store and opened an account in my company’s name so that I could get the contractor price which saved a couple of hundred bucks actually. I think the primer they had to order for me. Again, deal directly with the industrial side of SW which you can do on the phone, open an account, and then tell the local store exactly what you are looking for.
J.R. May
Wall, NJ