What causes it in paints?Thax.

If your talking about 2 stage paint ( base coat clear coat)It's a chemical that's added to the paint so when you do a repair it will match the factory paint orange peel. You can wet sand it and polish it and make it smooth as glass. The only way to get around it is a real slow hardener and hose the clear on pretty heavy on each coat. Allow plenty of time between coats so you don't get too many runs but hosing it on you will most likely get some.

Man I hope the above poster wasn't serious!

Orange peel is inadequate flow-out of wet paint. the faint failed to flow into an even film.
Causes, potential causes are many, including, but not limited to:
Inadequate film build
To high temperature
To little reducer
to low spray pressure
poorly adjusted gun (poor atomization)
poor quality paint
to long of flash time between coats
to fast of reducer

and other reasons

Pacnorth you might want to call your PPG or paint rep before you question my reply. You might learn something.

it amazes me when you ask paint questions how many different opinions you get are they right are they wrong ? nobody knows as far as the two above answers you guys are both right .
It all depends on the conditions and the painter what works for some in for example in Canada may not work in Florida .
from garage to paint booth in the same climate is apples to oranges
i paint in the garage and i guarantee my work is better then some of the expensive body shops around here . i think it all is trial and error and learning what works for your situation and you.

I agree with Pac.
Boise, Take a moment to see it from the other side. From what it appears, your post made it look like SOMEone adds a chemical to produce an UNsmoothe finish? Not to say that you are wrong, but you seem to be the only one here to mention it.
Most painters are aware of "Smoothie". This product is a Fisheye preventative. It is added to the mixed paint prior to paint application. It makes the paint flow over almost anything and sometimes it will increase orange peel. I am not a pro, but I have sprayed approx. 25 cars and trucks in 10 years. I'm constantly learning.
The definition of "orange peel" is that of a painted surface that is textured like the rind of an orange. How to reduce it? READ PAC's post. It makes sense.

So if its a chemical added to the paint to match factory paint jobs why do factory paint jobs have orange peel ?

It's not a product you can buy !!! The P-A-I-N-T M-A-N-U-F-A-C-T-U-R-E-R puts it in the P-A-I-N-T when the paint is made.
Factory vehicle paint has orange peel in it because the vehicle manufacturer either dips the car body in paint or sprays it quickly then forces it to dry fast by baking it. Either way the paint doesn't have time to flow out or lay flat so it has orange peel.
You can make orange peel less noticeable by putting more material on with each coat, over reducing, using slower hardener for the temp that your spraying in, slamming the paint droplets onto the surface by using more air pressure when spraying, but the only way to get completely rid of it is to wet sand it flat and polish it. Wet sanding is the final process of any quality or showcar paint job like ones found on a Bently, Ferrari, Jaguar, Foose, Codington etc. Call your paint rep or go take classes on how to paint they teach you things like this.

Or take some of the advice here and hang voodoo dolls in your paint booth or use a garden hose to spray it on or turn 3 times to the left the twice to the right then jump up and down 4 times before each coat

It looks like we did a fine job of chasing the OP away and probably left him more confused than when he asked the simple question.. WOOHOO strike one up for the MIDOL militia.

and by the way I might have a little experience painting cars http://www.moparmax.com/features/featurecar/v_5-resurrection-1.html

WOW That's great now finish it and win enough trophy's with it to get a Magazine interested in it so they want to run a 5 page article on it. Then I can show you my 92 Vette that was in Corvette Enthusiast Magazine in July of 2005. Then My 80 Vette then my current project my 73 Roadrunner or the 70 AAR Cuda show car I did for a friend. Don't show an UN-FINISHED car and try to make people think you know what your doing or your response has Value. Stop complaining about other peoples responses and go finish your car !!!!!

Its not my car to finish. It belongs to another member. I just made it straight and shiny.

You seemed stressed out, May want to see a Dr and get some blood pressure meds. Its the internet relax, were all profesonals here.

I don't paint, but 2 good friends of mine do, and from what I understand, the new clears are a "high solids" type and don't flow out as well as older stuff.
Not sure about laws down there, but we have to change over to waterbournes, and they are not the best yet..? Or low voc stuff, either way, the paints now are harder to lay down...

wow what can I say. I think I will just sit back and watch you make pretty interesting claims and bash people. Please do show us your "projects"

Back in the days of the white rabbit and hookahs smoking caterpillar it was in to dry orange peels and smoke em in your pipe.

Wow! That color looks good on a Cuda. What is it?
nice job.