What is the actual cause of orange peel?

I've never had major texture problems when painting, but I'm painting a new rocket right now, and it's clearly gonna have orange peel. I do my surface prep carefully, I shake the can for a good minute, use light coats - especially for the first coat or two - but this one started getting bumpy right away. I'm not sure if it's something I'm doing, or the weather (there was a light breeze which kicked up right when I sprayed a couple of times - a real annoyance), or what.

I am, though, using a can of paint I'd used once before, months ago, but it's still pretty full. I tested the nozzle before spraying, and everything seemed OK, but I don't know if that's it.

Fortunately, this is just a small scratch build, nothing fancy, but I want to know how I can avoid this in future when I'm painting something more special - or expensive. What is the actual, technical cause of orange peel?

Dispar, hate and loneliness cause orange peeling of paint.


TA

thobin said:

Dispar, hate and loneliness cause orange peeling of paint.


TA

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That must have been the problem.

I'm gonna be honest with you---There is a lot of answers to your question, so let's start. If your surface prep is good and smooth , then you can take that out of the equation. No spray gun--ok--that's gone. Here is what's left---temp---It can be a game changer--too warm and you can OP--too cool and you run or fog. Surface temp is critical, spray warm paint on a cool surface, you might get away with it---RUNS WOULD BE THE PROBLEM. Spray cool paint on a warm surface --all bets are off. I tend to spray on a warm surface but re coat quickly so the paint slicks out---YEA, TAKES PRACTICE.. Distance is a factor and that changes from vendor to vendor --as well as old to new spray cans---with the exception of primer , I toss my paints at 50% usage. Keep the nozzles clean(no exceptions here). There is no one formula and it's more art than science but,, Wet over dry-your asking for problems---Wet over tacky--should not OP /90% Success if temps are good(60-80%). Wet over wet--won't OP but chance of runs (40-60%) do it fast with thin coats in a warm area. That's the tip of the ice burg , so to speak. A good learning tool is primers. If you can get them to spray nice and smooth on a warm surface or warm temps with no dry spray, your on your way to mastering the dreaded spray can finish !!!!

Ya know, I should have started by saying --"your gonna get about a million replies to this"--My reply is just based on practical experience. Your going to have to learn along the way but--This----This----and this---are spray can --as well as everything else I do---just lean into it, you'll figure it out---H

I have painted hundreds of rockets over the last 35 years and and I can tell you I have found only one link that I can think of and that would be paint compatibly. It only seems to happen if I try to use two different brands of paint, now if it was just a coincidence stemming form bad prep or some of the other reasons that the hornet driver stated, I don't know. Really its just my experience and best guess.


Shake and mix the paint well, spray a bit out before you hit the rocket with the paint keep the coats light and ware gloves to keep the oils from your hand from getting on the rocket. And keep your rocket out of direct sunlight while its drying.


TA

hornet driver said:

I'm gonna be honest with you---There is a lot of answers to your question, so let's start. If your surface prep is good and smooth , then you can take that out of the equation. No spray gun--ok--that's gone. Here is what's left---temp---It can be a game changer--too warm and you can OP--too cool and you run or fog. Surface temp is critical, spray warm paint on a cool surface, you might get away with it---RUNS WOULD BE THE PROBLEM. Spray cool paint on a warm surface --all bets are off. I tend to spray on a warm surface but re coat quickly so the paint slicks out---YEA, TAKES PRACTICE.. Distance is a factor and that changes from vendor to vendor --as well as old to new spray cans---with the exception of primer , I toss my paints at 50% usage. Keep the nozzles clean(no exceptions here). There is no one formula and it's more art than science but,, Wet over dry-your asking for problems---Wet over tacky--should not OP /90% Success if temps are good(60-80%). Wet over wet--won't OP but chance of runs (40-60%) do it fast with thin coats in a warm area. That's the tip of the ice burg , so to speak. A good learning tool is primers. If you can get them to spray nice and smooth on a warm surface or warm temps with no dry spray, your on your way to mastering the dreaded spray can finish !!!!

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Ditto for the first part of Hornet Drivers post:
We all occasionally get a bit of Orange Peel. Generally its a contrast temperature between paint and substrate that cause the problems.

All that said: I empty every last bit of spray from any and all brands of Rattle Can Paints I purchase, I have Very Old Cans (5-15yrs)of Testors and other specialty spray paint that I use when needed as long as there is propellant enough to deliver it to the model surface.
My results are usually without OP problems but it is SUPER important that the surface being painted and the paint at about the same temperature. This allows the paint to flow out as intended by the manufacturer as the vehicle and solvents evaporate.
I also concur with HD's YEA! It Takes Practice!

Edit:
Almost forgot the most important thing I wanted to type!
I've Never seen an Orange Peeled paint job that couldn't be saved with a bit of elbow grease and two 3m finishing products. Perfect-it-III and most important Finessit-II. These two Liquid Polishing agents (not a buffing compound) can and will smooth out even the most stuborn of surface defects as long as there is enough paint on the subject to allow a tiny bit of removal.

Plus ten on the finessit polish. I use this at the factory to make our Honda and Accura finishes absolutely perfect. Orange peel is related to humidity there because we use a water/solvent emulsion base. Don't know if humidity is a factor with bugsprays.

If you read all of the instructions on the paint can you will find that many of them say something along the lines of; 10 minutes between coats, apply all coats within one hour, or wait “X” amount of time before recoating.

That “X” amount of time varies between 24 hours and ONE WEEK!!

If you don’t wait that “X” amount, bad things will happen, including but not limited to “Orange Peeling”.

Certain types of plastics currently used in small model rockets have a natural lubricating, think Delrin, property. These types of plastic can be painted successfully with many common paint types/brands but you should avoid using a primer beforehand.

The reason is that the color paint shrinks when it dries and it will pull and crinkle the primer off the plastic.

I avoid spraying Lacquer type paints over Enamel or Acrylic paints as this has never worked out for me.

For me It hard to track down to one cause. However If I mix different brands of primer It is more likely to happen. Rustoleum 2X primer is useless (more like a paint then a primer) and if you use Rusoleum filler primer (which I really l like) over it, it will orange peel. If you use a primer over a paint it is likely to orange peel. If you have to do any repairs skip the priming and just use paint.

terryg said:

For me It hard to track down to one cause. However If I mix different brands of primer It is more likely to happen. Rustoleum 2X primer is useless (more like a paint then a primer) and if you use Rusoleum filler primer (which I really l like) over it, it will orange peel. If you use a primer over a paint it is likely to orange peel. If you have to do any repairs skip the priming and just use paint.

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I totally agree with you about the 2X primer! It took me several rockets to realize it was junk. Sands like rubber! Now I only use Rust-o filler primer or sandable primer (even though they all say "sandable," I only go for the stuff that's called Sandable Primer).

I think I may have figured out what went wrong here, guys.

After I sand primer, I wipe the dust off with rubbing alcohol - a tip given to me by an experienced rocketeer. However, this time I did it just before painting. I think the evaporation of the alcohol may have cooled the surface of the rocket down enough that the temperature change between the paint and the airframe may have caused the orange peel.

Just a hypothesis, but it's the only thing I can think of I did differently this time. In any case, it's something I'll avoid next time, to be on the safe side.

Stop using old orange paint. :wink:

Sometimes it's excess spray pressure, sometimes it's not enough (poor atomization). When spraying lacquer or any non 2 component finishes that shrinks as it dries, you will have this problem. With lacquer if you want smooth glass finish you have to polish it after spraying. Or you can spray 2 components and assuming you got the technique right, you get very little if any orange peels.

If you were spraying laquer, the wind you mentioned was half drying the mist before it hit the rocket.
If you were spraying enamal, you were moving to quickly, or too far from the rocket.
Good advice is to look at the item at an angle so you can see your paint laying down.
You want it to go on wet. Hard to do on small round tubes I know, but you'll figure out the distance and speed.

Hi folks!
I know this is an old post but it's one that caught my attention!
It's also my first post here!

The question "What causes orange peel?"

The answer is: The very act of spraying/atomizing the paint to apply it!!!!

You turn the paint into little droplets (some littler than others due to can tip design, or the mix ration of thinners and reducers to the paint mix, the type of paint, the painting conditions etc.) during spraying and they gather on the surface unevenly, not laid down in a perfect even uniform layer, they are applied in "drops".

ALL paint orange peels when sprayed, the key is spraying technique.
Don't believe me? Take some flat stock, use a small piece of window pane (permanent adhesion is not an issue-this is a test! so don't worry about primer, just clean it real well with a good solvent.). You cant get much more perfect than that.
Take ANY kind of spray pain, be it can or spray rig or anything you can spray with and apply the best paint job you can.
Now wait a few days to let it dry a little and wet sand it with 600 or 800 grit sand paper on a block....but just make bout 6 to 10 passes over the paint and dry it off and look at the surface.....are there little "round" sanded spots??? YES...LOL
It's from the spraying!!!

Back in the old days when cars were painted with lacquer, you color-sanded the orange peel out of the finish and then polished the color-sand scratches out of the finish.
Lacquer is quick to apply, quick to dry and cure (yes those are 2 completely different things) but to get a really deep shine you have to color-sand and polish it.

Enamels on the other hand are supposed to get that deep shine without all the post-paint work, but (and usually typically) it leaves the orange peel.
The amount depends on spray technique!!!

Enamels have come a long way in the last 2 or 3 decades especially in the rattle cans (not to mention the poly-urethanes and epoxies but that's another set of animals but still rely on technique) to try to make it easy to have a nice finish without a lot of work.
Of course you sacrifice cure time, but "use of item painted" has come a long way as well.

And nothing to do with orange peel but ALWAYS read the instructions for recoat/dry/set/cure windows, and some paint have a color sand/polish window, miss that and you'll NEVER get those c-sand scratches polished out!

After all that explanation,
HERE'S the way to MINIMIZE it...regardless of paint type and adjusting for temp and humidity etc.

On your last coat it MUST be a full wet coat that is just on the edge of running/sagging so the surface can flow out wet and level up those atomized "dots" of paint!

I hope that helps!!!

Steve

Saturn652 said:

Hi folks!
I know this is an old post but it's one that caught my attention!
It's also my first post here!

The question "What causes orange peel?"

The answer is: The very act of spraying/atomizing the paint to apply it!!!!

Click to expand...

I disagree. I used to work in a semiconductor fab plant. The photoresist was applied by squirting it onto the wafer in a blob, then spinning the wafer to spread it out. No spraying. We still had orange peeling. It's caused by uneven evaporation of solvent.

Short answer: Paint is comprised of three major components: pigment, solvent and binding agents. The solvents in laquer paint are "hotter" (are better at solvating more things, also in this case tend to be more volitile and dry quicker). When you spray enamel paint and then laquer over top the solvents in the laquer are sufficiently frisky enough to partially solvate the binding agents from the enamel. Once those binding agents soften then a whole lot of bad things can happen (most result in the overarching term of orange peel).

Really short answer: Chemistry.

There seem to be two separate things being called "orange peel". One is poor atomization giving a "bumpy" surface. Basically the paint hits the part in globs and never fully flows into a smooth surface. The other is paint that goes on smooth but dries into a bumpy finish (this is what I always thought was "orange peel" - an effect that occurs during the drying / curing, not during the initial application). Which is the OP referring to?

Cl(VII) said:

Really short answer: Chemistry.

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Oh I can't resist, everyone knows chemistry is just applied physics

Even shorter answer: Physics.

Vethen said:

Oh I can't resist, everyone knows chemistry is just applied physics

Even shorter answer: Physics.

Click to expand...

That was uncalled for. :wink:

I can back that one off once more too, and leave us both out.

Root answer: Math

Here is a good illustration of orange peel cross section



If you've had problems with orange peel before, chances are you're still going to have them. The easy solution is to wetsand the topcoat with 2000 grit not putting too much weight on the sandpaper. Just lightly sand the surface going in one direction. Don't do it too much, because you can shed off more than you intended. After that, dry the rocket first then use a damp rag to clean off any debree on the rocket, making sure to dry again. You may then finish the rocket off by applying car polishing compound, (I prefer turtle wax brand) to give it some luster and hide scratches, and a layer of canuba wax to act as a protective shell to your paint.

thobin said:

Dispar, hate and loneliness cause orange peeling of paint.

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Fear leads to anger. Anger leads to hate. Hate leads to orange peel.

I do a a good amount of model painting at work, both lacquer and one part basecoat paints (Chromabase), both followed by clear or flat clear lacquer for a top coat.

My experience is that orange peel is caused by two things: the size of the paint particles (tied into the viscosity of the paint plus the spray orfice being used) and the "speed" of the reducer being used.

If you have larger paint droplets and a fast reducer, the paint will dry on the surface before it has a chance to level out, leaving some amount of orange peel. This can often be adjusted by changing the speed of the reducer.

By tweaking the speed and amount of the reducer that I am using with gloss or flat clear lacquer, I can get a glass smooth finish with clear lacquer that requires no sanding or polishing to look great.

With spray guns, you have a lot more control over the paint droplet size and over the amount of reducer added to adjust the viscosity. One of the disadvantages of spray cans is the lack of control over both of those factors.

I know a guy that decants his favorite spray can materials into his HVLP spray gun to get better performance and control over the paint be spraying it from the gun.

sooner.boomer said:

I disagree. I used to work in a semiconductor fab plant. The photoresist was applied by squirting it onto the wafer in a blob, then spinning the wafer to spread it out. No spraying. We still had orange peeling. It's caused by uneven evaporation of solvent.

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Hey Sooner,

Thanks for the reply, you did make a good point...BUT...
I think you're kinda comparing an apple to an orange on that one....
What you are referring to is not designed to be a finish coat if I'm not mistaken (correct me if I'm wrong), so it has none of he characteristics designed into todays modern paints....plus the act of spinning it to distribute the medium over the plate/wafer by design is ALSO to increase air flow to quicken dry time, which is counter to the theory of finish painting......
And too Sir, I did say in capitol letters "MINIMIZE" orange peel....with a properly sprayed paint job, the solvent evaporation amount of orange peel is almost negligent....

There is a difference between color-sanding for 5 minutes to level 10 sq/ft of surface and sanding 10 minutes to level 2 sq/ft of surface....and that is in the flow-out of the coat...spray technique....
99.9 % of the orange peel that is big enough to cause concern is caused by spray (faulty mix-faulty temps-faulty whatever-FAULTY TECHNIQUE), NOT by solvent evaporation anomalies.....

....what have I started!!!!! LOL

sooner.boomer said:

It's caused by uneven evaporation of solvent.

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not uneven evaporation, but speed of evaporation. if you have uneven evaporation of solvents then theres a problem with compatability of the materials in the coating.
and only one possibility.

Ok I read thru this and as far as I see , no mention of "Fish-eyes".
Some may confuse the two.

If any wax ,grease or the like is on the surface you get fish-eyes.
A bad enough case of small eyes can look like OP.
Using a contaminated rag can do it.
If wax is in the air,on other surface in your paint area, you can contaminate your hands.rags.tools ect.

I did 4 yrs of Autobody Paint & Repair back in the 70s. So I am a bit laxed on my info. And may only apply to "resurface paint jobs

So, I give you this.....https://www.ehow.com/list_7297378_causes-fish-eyes-car-paint_.html

And this....

Either way, this info should prove helpful to someone here. Good luck!