Freshly Painted with Orange Peel

[RobR93]

I'll try starting with the 1000 grit tonight. I believe I got good coverage of paint. So if Im careful, I won't get too for down......thanks for the tips and I'll be looking forward to Mikes response. do I wait for the one other 80 degree day we may get here in NY and try to reshoot? I have a wood stove in the garage, but am not keen on open flames and paint spraying.....and yes I have a respirator.....thanks for asking!!!!

PS.....Im learning as I go.....some mistakes will obviously cost me extra time/money/effort, but I will have learned something!!!!

[RaskyR1]

we are not supposed to post links so I'll just copy paste the post in the thread...PM me if you want the link.


"Basics of Basics" Atomization and gun set up.
By Brian Martin

Being HVLP and low VOC products are the way the industry’s going I will be referring to them in this discussion on painting and paint guns. Most all basic issues dealing with HVLP can be applied to conventional guns, atomization is atomization. The HVLP just arrives at it differently.

The object of the spray gun is to break up the primer/sealer/paint/clear (I will call this “PSPC” from here out) into small particles and lay them in neat little rows on the panel being PSPRed. So the whole outcome rests on how well the gun is doing this. Picture the droplets of PSPC coming out of the fluid tip of the gun and then the air “slapping” them into smaller droplets.

You have two things that help you with this process, air and solvent. Solvent can mean something that is already in the PSPR from the manufacture or something the manufacture has told you to add to it. By the way, you should always mix in proper ratios as instructed in the tech sheet. The thinner (less viscosity) you get the PSPR or the more air you have at the fluid tip of the gun the more it will break up the PSPR. The target for you is getting the perfect balance needed. Too much solvent and the PSPR will have no body, fill, durability, etc. Too much air and you blow the PSPR everywhere but the car, poor adhesion, excessive texture, etc.

So, the answer is proper air supply and gun (and fluid tip) choice and how you adjust it.

With today’s high solids-low VOC (Volatile Organic Compound, you know the bad stuff that goes up into the air we breathe) products there is less solvent. And with HVLP guns there is less air at the cap to break up the PSPC, proper air supply and gun setup is more important than ever.

FIRST THINGS FIRST, your compressor and air supply.

An HVLP gun requires more VOLUME of air to operate (the V in HVLP, High Volume Low Pressure). Now you may notice that your HVLP gun is adjusted at maybe the same PSI as an old conventional gun, around 50 lbs at the gun (many HVLP guns are set at much lower though) so where is the “Low” in PSI they are talking about? It is at the actual air cap where the air and paint come out. An HVLP gun has only 10 lbs at the cap while a conventional has upwards of 50! So the VOLUME of air (CFM, Cubic Feet per Minute) is the key to proper atomization with an HVLP.

This 10 lbs I am mentioning is AT THE CAP where the air and paint comes out. It is not measurable without a special air cap that has a gauge built in to it. This air cap costs about $150.00 (and you would need a different one for every brand and model of gun you use) and is not needed to set up or tune your gun. Just looking at the droplet patterns will tell you everything you need. I only refer to it to make a point about HVLP operation.

If you have a gun that requires 15 CFM you will need a compressor and plumbing that will produce that at a very minimum. There are HVLP guns that need as little as 7.5 CFM so you can get good results even from a smaller compressor. Air supply is a complete subject by it’s self so lets assume that you have the air supply needed and move on to gun set up.

So atomization is the key, but why? Why can’t you just lay it out wet and let it “flow”, as an old painter will say. Picture a jar full of bb’s, they will represent well small, atomized droplets of PSPC. The gaps in between the bb’s is solvent. Now picture a jar filled with marbles, they will represent large, poorly atomized droplets of PSPC. The gaps in between are, you guessed it, solvent.

If you apply your PSPC in large poorly atomized droplets, what you will have is a film full of solvent. This can and will cause slow curing, shrinkage and dieback (the loss of gloss in the hours and days after application).

So, now that we have learned the need for gun set up, how do we do it? Lets start with the fluid tip choice. The newer high solids low VOC PSPC products need to be broken up more, so a smaller fluid tip is needed.
Basically you want the smallest fluid tip that will still allow you to PSPC the particular part you are PSPCing keeping the entire thing wet and in a fair amount of time. In other words a 1.0 tip would be beautiful for clearing one fender, but would be lousy to paint a complete. The application would be way to slow and the first panel would be way to flashed by the time you got around back to it. So you need to compromise, a 1.3 is a great all around tip, while a 1.5 though getting a little big, can get you by. If you read the tech sheet on the particular product you are shooting, it will have a recommendation for fluid tip size.
There are needs for other tips, for instance when shooting polyester primer you may need as big as a 2.3, but for urethanes and epoxies, the 1.3 or 1.4 will work great. If you plan on using a pressure pot or paint a bus, all bets are off and we would need to study a little bit more.

As an example of the use of a 1.3 tip I did a test once that proved the point well. I shot two panels of metal with a med solids urethane primer. One was shot with a 1.3 super high atomizing top of the line topcoat gun. The other was shot with a 1.5 (or a 1.7 I can’t remember) “hoser” primer gun. Three coats were applied and after a full cure (the one shot with the larger gun took MUCH longer to flash and cure by the way) the film thickness was measured. The one shot with the 1.3 tip was 2 tenths of a MIL thicker! The larger gun laid out the marble sized droplets full of solvent and when the solvent flashed the film shrank.

Air supply is a subject that could fill many pages by it’s self. So we are going to assume you have that covered and move on to gun set up.

You need to “tune” your gun EVERY TIME you use it just as you would tune a guitar before you perform. This is done with a very basic spray out pattern test. This very basic test tells you how your gun is atomizing and you adjust it to achieve the best atomization you can.

Lets do a spray pattern test:

Set the fan width as need (you don’t want to change it after you have “tuned” the gun). Turn out the material knob about 2 ½ turns. This is the “mixture” adjustment, kind of like the idle screw on a carburetor. The farther in it is screwed the lower the fluid to air ratio is and the smaller the droplets will be. The farther out it is, the higher the fluid to air ratio is and the larger the droplets.
Set the air pressure at the inlet to the gun to the manufactures specs. On an HVLP gun this spec is usually found on the gun and is the maximum PSI it can have while still maintaining the maximum 10 lb at the cap for legal HVLP transfer efficiency (68 %). You are now ready to do a test spray out.

Tape a piece of masking paper on the wall for the test. Hold the gun at a right angle to the wall, just as if you were going the wall. Hold the gun at a spread out hands distance (about 8” or 22cm). Pull the trigger to completely open for a split second and then close it. You want an ON-OFF wide open-completely closed in ONE movement. You should have a cigar shaped pattern with complete coverage in the center with fading coverage going away from the full coverage cigar shape in the center. The center should be fully covered without any runs. If you have runs, either you are holding the trigger too long, you are too close or the gun is simply applying too much material. In which case you need to screw in the material knob or turn the air pressure down. But most likely if you have turned the material knob out the 2 ½ turns and the air is set at the factory specs, you are just too close or holding the trigger open too long.

The droplets you see trailing off the center are what you will use to “tune” your gun.

Turn in the material knob to make the droplets smaller (and or raise the air pressure). The balance you need to attain is the smallest droplet size possible before you loose the coverage desired. In other words if you turn in the material knob too far, not enough material will be coming out to cover the panel!

Now, you’ll notice that I said, “raise the pressure to the gun”, while earlier I said to set it to manufactures specs. We are talking a very small adjustment. It is a fine balance in material to air ratio and a little more air than specified is okay. Even if it is an HVLP gun the inlet pressure recommended is to maintain the 10 lb limit at the cap. Well, about three quarters of the country has no regulations for HVLP use so if you go over the 10 lbs all it will do is atomize the material a little better. You may loose a little of the benefits of HVLP though. But remember you have a lot of control with the material adjustment knob.

After you are happy with the droplet size, DON’T TOUCH THE FAN CONTROL. It will change the PSI at the cap and will change the atomization you worked hard to get.
Do this spray out every time you spray as material change, temp, and humidity will necessitate a spray out droplet pattern test. Good luck!
Click here to see a sprayout pattern

[Blackthorn One]

I'll try starting with the 1000 grit tonight. I believe I got good coverage of paint. So if Im careful, I won't get too for down......thanks for the tips and I'll be looking forward to Mikes response. do I wait for the one other 80 degree day we may get here in NY and try to reshoot? I have a wood stove in the garage, but am not keen on open flames and paint spraying.....and yes I have a respirator.....thanks for asking!!!!

PS.....Im learning as I go.....some mistakes will obviously cost me extra time/money/effort, but I will have learned something!!!!

A trick you can use to make your paint atomize better in cold weather is to put the paint can in a pot of very warm water before you shoot it, for about 10-15 minutes, to make sure it is completely warmed up. It really does improve your painting. Just be sure that the paint can is absolutely dry before you transfer paint from the can to the cup. You don't want any water to get in the paint. Practice a little on that hood first.

[Mike Phillips]

Here's the full size picture as it was attached...




That's pretty bad, here's some bad orange peel,





He sanded and then buffed and got it to here,




But says he also buffed through a couple of places...


Like most already commented, the orange peel in the finish is pretty severe and you might be better off sanding and the re-shooting more clear and try find out where the orange peel problem is coming from in your process.

If you have a thick enough film-build of clear you could theoretically sand the paint flat and then buff out your sanding marks but keep in mind that sanding removes some paint and the compound and polishing steps both remove some paint so if there's not enough film build to work sooner or later you will buff through the clear and expose the color coat.

Even if you re-shoot the paint you're still going to need,

• Rotary Buffer - It's possible to remove sanding marks with a DA Polisher or a Flex 3401 but the most EFFECTIVE method is with a direct drive rotary buffer.
• Wool Cutting pad
• Foam Polishing Pad
• Aggressive Compound
• Medium to light cutting polish
• Sanding or Finishing Papers - Finishing papers are a higher quality sandpaper
• Backing pad for your sandpaper
• Spur

That's a minimum of supplies. A wish list would include,

A pad washer to clean your pad after buffing a section or two. You can clean your pad with a spur but a pad washer gets the pad so much cleaner.

A DA Sander - It's faster to sand with a DA sander and a heck of a lot faster to remove DA sanding marks than hand sanding marks.

The Mirka Abralon System or the 3M Trizact system, both work great.

A DA Polisher and some small foam pads for the final finish polishing to insure there's no swirls

Swirl Finder Light is always handy to check your work.

Grit Guard in a 5 gallon bucket to store your sanding papers and/or sanding discs

Painter's tape

That's a partial list but a good start...

[Mike Phillips]

I'll try starting with the 1000 grit tonight. I believe I got good coverage of paint. So if I'm careful, I won't get too for down......thanks for the tips and I'll be looking forward to Mikes response. do I wait for the one other 80 degree day we may get here in NY and try to re-shoot? I have a wood stove in the garage, but am not keen on open flames and paint spraying.....and yes I have a respirator.....thanks for asking!!!!

PS.....Im learning as I go.....some mistakes will obviously cost me extra time/money/effort, but I will have learned something!!!!

I posted a list of minimum tools required which includes a rotary buffer, if you don't own one you can probably rent one at your local tool rental store.

You can remove sanding marks by hand but it's a lot of work but also a good work out...

I would never usually recommend starting with grits lower than #1200 but the orange peel is so bad that you initial cut could be with #1000

Some will say even lower but I'll let you decide, #600 and #800 grit papers are pretty darn aggressive, I'd rather start at #1000 and then work my way up.

Let us know if you get the rotary buffer as you'll still need a backing plate and a wool cutting pad.


Take some good before and after shots...

[Blackthorn One]

I posted a list of minimum tools required which includes a rotary buffer, if you don't own one you can probably rent one at your local tool rental store.

You can remove sanding marks by hand but it's a lot of work but also a good work out...

I would never usually recommend starting with grits lower than #1200 but the orange peel is so bad that you initial cut could be with #1000

Some will say even lower but I'll let you decide, #600 and #800 grit papers are pretty darn aggressive, I'd rather start at #1000 and then work my way up.

Let us know if you get the rotary buffer as you'll still need a backing plate and a wool cutting pad.


Take some good before and after shots...

Perhaps I should have been more clear about how to use the 600 or 800. When you use those on this, DO NOT sand all of the orange peel off with either of those grits. Get most of it off with the 600 if you need it, and then switch to the 800 and then still leave just a bit of orange peel behind and finish off all of the orange peel with the 1000 or even 1200. This will ensure that you don't make too much work for yourself sanding out sanding scratches from the 600 or 800 and at the same time, removing too much paint in the process. Just use the 800 or 600 if you really want to make it go faster, but you should be able to get all of the sanding with the 600 done in about 2 or 3 minutes tops by hand out of that whole fender. Then it would be a minute or a minute and a half with the 800, and then get all, or 99% of the orange peel out with the 1000, which at that point would not be much more than removing all of the 800 scratches, and then finish it off with the 1200, to get all of the other scratches out, and get any tiny bit of orange out of the finish. You could do the whole thing with 1200 or 1000, but it would be a little faster this way, unless the paint is real soft. If the paint is soft, then 1000 and 1200 is all you need.

[mbkite]

I am not a body man but i did spray one of my cars.
I used enamel paint with a hardner. With that enamel i used laquer thinner to thin the enamel paint .. not enamel reducer
Enamel reducer takes too long to dry.. With laquer thinner you have low min and high temp .. for this weather use mid temp. Mix the paint and hardner and thinner so its like watter very thin.. shoot 1st coat a little light then the second coat thicker and the 3rd coat realy wet.
I sparyed an olds cuttlas signal red with black stripes this way and it came out very good.. use the paint hardner so you can wet sand..

[Mike Phillips]

Perhaps I should have been more clear about how to use the 600 or 800. When you use those on this, DO NOT sand all of the orange peel off with either of those grits.

Just to note, I completely understood that and my point was that if possible I would prefer not to start that low nor recommend it to anyone especially if they're new to wet-sanding, cutting and polishing.

I've never had to chop down any orange peel as bad as in his picture knock on wood.

I appreciate your clarifying however as as time goes by we all need to remember that not just the people posting to this thread will read this thread, hundreds of Lurkers will read this thread so plenty of detail makes a great answer. That's why I try to type out answers that answer the question for the OP and also for all the Lurkers which usually includes lots of extra information.

[Blackthorn One]

Just to note, I completely understood that and my point was that if possible I would prefer not to start that low nor recommend it to anyone especially if they're new to wet-sanding, cutting and polishing.

I've never had to chop down any orange peel as bad as in his picture knock on wood.

I appreciate your clarifying however as as time goes by we all need to remember that not just the people posting to this thread will read this thread, hundreds of Lurkers will read this thread so plenty of detail makes a great answer. That's why I try to type out answers that answer the question for the OP and also for all the Lurkers which usually includes lots of extra information.

My apologies. I was not talking to you. I know you know all about it. I was quoting you and trying to talk to the OP. Too confusing.
Right on, about posting for everyone.
Right too, of course about starting with too coarse a grit. It just depends upon how soft the paint is. In his case, it's probably soft enough to use 1000, but if it was much harder, then 600 might be in order. Like I said at first, he should try it first with 1000 and see how it goes, and if it seems like 1000 won't cut it, then to try 800 or even 600. I apologize if I offended you by suggesting YOU didn't know.

[Mike Phillips]

I apologize if I offended you

Not at all...


I used to have a route calling on Bodyshops, Dealerships and Detail Shops and the hardest call were believe it or not... Detail Shops, or more specifically Detailers. Seemed like once they became successful it was hard to show them anything new. What this taught me was to always be willing to learn from other, never place a wall around yourself. I perceive you to be a painter and when it comes to painters and other detailers I'm all ears.

You might like this, it was my route truck. I could have bought a white Astro Van or something like that as it would have made more common sense and it would have been more practical but I knew that car guys would connect with the Milk Truck. Besides getting me in the door, it was a blast to drive with a 396 Big Block Chevy!




The license plate said, 66 Milk