What causes “orange peel” when spraying paint?

Since IDO is the font of all knowledge…

I was respraying an outboard cowling yesterday. I put the color coat on on Friday and did a final wet sand to get rid of a few dust flakes, etc.

Then I went to spray on the clearcoat. I’m just using Rustoleum clearcoat, I’ve done this many times before.

And it freaking orange-peeled in spots! I had about 3 spots the size of a quarter where the paint went to an orange peel texture. Dang nabbit!

What causes this? Was the color coat not cured even after 2 days of stitting in my warm garage? Did I get some kind of surface contamination on it?

I’ve used this combination of color coat and Rustoleum clear coat before many times wiht no issues, so it’s NOT an issue with the paints being incompatable.

Any ideas?

Grouse

I’m sure you checked this but, sprayer setting? viscosity of paint?Might be coming out to thick. Maybe multiple thin layers with light wet sanding. I’ve only done it a few times but thats what I messed with.

Back in what feels like a former life I was did a lot of painting. Orange peel usually is caused by improper application. The worst offender I’ve seen is when the paint gun is held too far from the surface being painted which allows the thinner in the clear to start to evaporate before the material builds up on the surface. It can also be caused by applying the clear too heavily in spots causing the surface to dry at inconsistent rates. But these are just a couple guesses.

I second James’ thoughts on the nozzle being too far away. I spray a lot of lacquer and that is an immediate way of knowing you held the gun too far away.

Hmmmm. Operator error. Guess I was hoping I had something to blame besides me.

Yep, probably keeping the nozzle too far from the surface. I’m gun-shy about sags, nothing worse than running the damn paint and then having to wait, sand, respray, etc. Probably getting too far away.

Will try again tonight and get it closer.

Many thanks.

Grouse

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Hmmmm. Operator error. Guess I was hoping I had something to blame besides me.

Yep, probably keeping the nozzle too far from the surface. I’m gun-shy about sags, nothing worse than running the damn paint and then having to wait, sand, respray, etc. Probably getting too far away.

Will try again tonight and get it closer.

Many thanks.

Grouse

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When doing these projects it’s always a good idea to keep a mirror close at hand. That way when things go wrong you know who to blame.

From the folks at DuPont:

Origin and Potential Causes:
Improper gun adjustment and techniques. Too little air pressure, wide fan patterns or spraying at excessive gun distances causes droplets to become too dry during their travel time to the work surface and they remain as formed by gun nozzle.
Extreme shop temperature. When air temperature is too high, droplets lose more solvent and dry out before they can flow and level properly.
Improper dry. Gun fanning before paint droplets have a chance to flow together will cause orange peel.
Improper flash or recoat time between coats. If first coats of enamel are allowed to become too dry, solvent in the paint droplets of following coats will be absorbed into the first coat before proper flow is achieved.
Wrong thinner or reducer. Under-diluted paint or paint thinned with fast evaporating thinners or reducers causes the atomized droplets to become too dry before reaching the surface. Too high viscosity.
Low shop temperature.
Too little thinner or reducer.
Materials not uniformly mixed. Many finishes are formulated with components that aid coalescence. If these are not properly mixed, orange peel will result.
Substrate not sanded thoroughly

Prevention Techniques:
Use proper gun adjustments, techniques, and air pressure.
Schedule painting to avoid temperature and humidity extremes.
Select the thinner or reducer that is suitable for existing conditions. The use of a slower evaporating thinner or reducer will overcome this.
Allow sufficient flash and dry time. Do not dry by fanning.
Allow proper drying time for undercoats and topcoats. Not too long or not too short.
Reduce to recommended viscosity with proper thinner/reducer.
Stir all pigmented undercoats and topcoats thoroughly.
Prepare and sand substrate correctly.
Follow recommendations on technical data sheets.

Remedy
For mild cases, sand and polish using recommended materials and techniques.
In extreme cases, sand down to smooth surface and refinish, using a slower evaporating thinner or reducer at the correct air pressure.

I work at a sheet metal shop. I asked a painter and they do a lot of texture (orange peel) how they get it is by turning the air pressure down to get the paint to spit out.
The thicker the paint the bigger the drops. So check your air pressure and paint thickness.

As a tech/painter in the collision industry I would guess if its only in some spots it was a contaminate on the color coat. Sounds like what you are describing is actually clusters of what we like to call “fish eyes”. Caused by finger prints, grease, oil, armor all, etc. Orange peel is a possibility but generally if you were consistant with your technique the whole cowling will be peely.

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As a tech/painter in the collision industry I would guess if its only in some spots it was a contaminate on the color coat. Sounds like what you are describing is actually clusters of what we like to call “fish eyes”. Caused by finger prints, grease, oil, armor all, etc. Orange peel is a possibility but generally if you were consistant with your technique the whole cowling will be peely.

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Think this is what you have. The Dupont post is acurate for orange peel. Short version,paint sets before it flows out for whatever reson. Your thumb print is about the size of a quarter Resand smooth, clean clean clean. Once it’s clean don’t touch the surface and get some latex gloves and you should be allright. Had a guy work for me that had a father in law was township commisioner that tried to paint some trucks himself. After totally screwing them up he called my employee to look at it. He read the can and told him here’s the problem. Pointing at the part that said for professional use only

Being that it was only in a couple small areas I would say contamination. You can never have it to clean! If the color coats were to heavy in those spots it will give you orange peel and the clear will magnify it. Oil from your hands even if you think your hands are clean will cause it. using a good wax and grease remover helps. One thing to keep in mind when you are using a spray gun there are four fingers pointing back at you and one pointing forward, meaning more times than not there was operator error. Nothing against your ability.

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Yep, probably keeping the nozzle too far from the surface. I’m gun-shy about sags, nothing worse than running the damn paint and then having to wait, sand, respray, etc. Probably getting too far away.

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Trick to getting around sags that my former boss taught me is to do several light coats rather than try to do one heavy coat.

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Yep, probably keeping the nozzle too far from the surface. I’m gun-shy about sags, nothing worse than running the damn paint and then having to wait, sand, respray, etc. Probably getting too far away.

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Trick to getting around sags that my former boss taught me is to do several light coats rather than try to do one heavy coat.

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You still need a decent first wet coat if too dry there starts the orange peel. I would say contamination was your problem, when spraying clear if you can view the work from the side to see the application as you lay on the paint.

All right, I should say from the outset that I was assuming the problem WAS, in fact, me. It usually is. Like engine mechanics, welding, carpentry,woodworking, electrical, etc, having grown up in the middle of nowhere, I didn’t have much opportunity for formal training in the useful arts. I did get a lot of OJT, however…

OK, so the cowling is again wet sanded and I cleaned it twice using simple green. Luckily, the wet sanding didn’t go through the color coat, so I don’t have to respray with color. It is now laying in my indoor shop covered in a clean towel to protect it from dust.

Hopefully it was surface contamination and/or nozzle too far from surface.

Now, as far as technique, when we apply clear coat, how much time should I give it between coats? Is this like spray on, wait 10 mins, and spray again?

And any tips for getting a really nice even clear coat would be greatly appreciated.

BTW, the back story is that this outboard is the sweetest little 1980s 8 HP Johnson. I rescued it from a garage sale. As is often the case, the elderly owner bought it in the 1980s, used it faithfully for 5 days a year on his annual trip to a small resort, and it sat for the rest of the time. Sadly, the owner died last year and the outboard has been beaten up a little in storage and it looks like at one point it was actually stored upside down resting on the top of its cowling.

The lady at the sale said the motor hadn’t been run since Grandpa’s last trip to the resort about 7-8 years ago. I bought it without being able to run it, took it home, changed the lower unit oil, put it in my test tank, said a prayer, and pulled the cord. It fired on the second pull. Everything works perfectly.

God bless ye OMC. The little 8 HP deserves to ride again.

Grouse

Orange peeling can also be caused by a dirty surface such as the oil from off the fingers. Not enough pressure so the spray doesn’t get to a fine mist is another.

A trick I use is I wipe down the surface with the thinner Id use to clean off the paint from a surface, in other words cleanup, just before spraying. The spray hitting a moist surface has a tendency to flow better unlike a dry surface. Another trick is to spray a tack coat and let it set just enough so the next coat will hang on that coat. You can spray a thicker coat with the second one and get it too gloss better.

Holding the spray nozzle too far away from the surface will also cause an orange peel and especially on lacquer because it dries so fast and then looses some of its ability to flow once it hits the surface, it will stick but be a coarser spray.

If you have a quart sprayer and you want the coat to really even out and shine, spray pure lacquer thinner over the paint just before its completely dries and is still slightly pliable, but not to much or it will melt the finish and it will then haze, this is called a lacquer thinner wash. With this process timing is essential so don’t experiment on anything unless your sure you can get on the right amount. As a rule of thumb put on an amount of paint, to the point where its almost ready to run and then stop, this is the right amount for coverage and to get the best shine from the surface and will eliminate orange peeling.

You can also premoisten almost any surface using what the cleanup calls for as a flowing agent, even water before latex and the paint then just glides on.

When it comes to the clear coat thickness, spray it on to the point where its almost ready to sag, then thats enough.

Old motors, especially the small ones are very cool and its amazing how well built they were and how easily they run. I’ve got a few and one is a 1937 Johnson, opposed cylinders thats supposed two run and I think it will. I got it from a lady whos husband passed away. It still has the same gasoline in the float bowl from the last time it was run in the early 60’s, the cork float is shellacked and still floats in the float bowl.

Simple Green will leave a soap film so before spraying clean it with Rubbing alcohol or paint thinner check a spot where it won`t be noticed to make sure these will not lift your coat of paint. Me I would spray a smooth coat of clear and let dry until hand slick, in other words I can run my finger lightly across the clear and not leave a mark then hit it with my second coat. This way the 2 coats should melt together. Doing a really slick finish with a rattle can get interesting, I would also do this when it is a little cooler temp that way the paint will not set as fast and will let the paint flow together a little more.

GOOD :UCK