Painting techniques

We had a forum in St. Paul recently ( we being the Minnesota Wing of Van's Airforce...or RVOPA,..or... something) and one of the speakers was on the subject of painting. In fact, wrote up a synopsis (http://www.visi.com/~bcollins/rv/).

Anyway, I thought it was just me who had trouble with HVLP. I'm using it for priming using the SW wash primer and I'm just not happy with the blotches etc.

Our speaker suggested that even professional auto body painters need a LOT of practice to get comfortable with HVLP and even then, he thinks the HVLP is much more motivated by environmental interests than quality painters.

Now the fuselage kit is due to arrive and I'll have to get down to actually painting the interior at some point. I'm curious how many of you use HVLP, how many of you use regular pressure sprayers, and how many use rattle cans. And what tips do you have?

I did like Joe Schumacher's technique on "From the Ground Up" with the splatter approach but I'm not sure how he accomplished it. OTOH, the way I paint with the HVLP, I suppose the answer, "just do what you've been doing."

Bob
St. Paul

Thanks for the link. I painted my last two projects, but not this one. I'll pay someone to do it.

BTW, I doubt he added 50 lbs. to his airplane. It's more like 12 to 17.

I have a Citation HVLP system and found it to be a good unit giving me great results. Some of the cautions when using it are:

Make sure your paint is properly thinned so it flows out properly

Make sure you are using the correct needle jets and orfices for the type of paint you are using. Some primers require a larger orfice or more thinning.

Being a novice and only having sprayed two airplanes, one in 2000 and one in 2004, I thought the unit was pretty easy to use and my results were really good. Our Airpark neighbor is spraying his first plane and is having great success using my Citation.

Our only prior experience was rattle cans.



Note the Madrid Red tennis shoes!!!

I have used a Devilbus regular spray gun for years but never used a HVLP. A good friend and body man has the same feeling about HVLP guns. He thinks the old guns work better but waste more paint. The key to using SW wash primer is to make sure you stir the paint with a paddle and drill motor before using and thin it with 1-1/2 to 2 parts activator instead of 1 part like the directions say. I spray using one part paint and two parts activator or thinner.
I have found that I get much better adhesion from the SW wash primer than the rattle cans. Handling the parts will scratch the primer off very easily when using the rattle cans even after a couple of weeks. The SW wash primer sticks like glue and seems very durable. That said, I may switch to Dupont primer simply because the color and appearance is better to my eyes.
One last thing the store will charge you about $150 a gallon for SW wash primer but if you tell them it is for OEM Aircraft painting the price drops to about $65.00 a gallon which is cheaper than anything else I've seen for good self etching primer. I am not a professional painter so your milage may vary.
Jim 90919 wings Arkansas

RV9AVIATOR is correct. Mixing SW with 1.5 - 2 parts reducer/catylst is the answer. I also am using a HVLP gun and have found spraying at 90 psi with it mixed thin and the needle open very little works awesome. It looks like the coating the QB comes with from Vans. Very thin and even.
GOOD LUCK!

Jeff

I have a turbine HVLP gun, and I did find it hard to use. Changing the needle/cap to a finer atomizing one helped somewhat, but it still didn't give a smooth finish
I since bought a low end HVLP DeVilbiss gun and found it to be great. I've painted the aileron, cowling and wheel pants on my Tiger, and it left a great finish with DuPont Centari paint.
The better brand (as opposed to knock-offs) was easier to adjust and easier to use, and well worth the price.
This is the model I got http://tinyurl.com/3zxjb

...good luck painting. At an EAA meeting, a paint represenative suggested going to the auto wreckers and buying a few auto hoods to practise on. Testing on large areas is much easier than small areas...

gil in Tucson

Love my Citation HVLP Setup

I primed the insides of my -8 with SW wash primer shot thru a Citation HVLP system. The turbine HVLP was a pain to get used to (my shooting experience is with std hi pressure guns) but the SW needs to be thinned big time to shoot well. An hour later, I shot the SW with an Epoxy zinc primer.

Shooting the PPG Concept Urethane with the HVLP was tons easier and in no time I was back to my normal shooting style, and it all came out better than I expected with the HVLP Citation system. I also love having the forced cool filtered air to my face during spray ops.

My experience with rattle can wash primers: I have been using them for small touch ups, and for all the numerous fuselage interior parts that I fabricate as I go along. I then shoot a rattle can gray primer over the self etching stuff. I thought this was a good system, until I shot the PPG top color. The PPG polyurethane color over the rattle can self etching primer did not adhere very well compared to top color over the SW industrial wash primer with an Epoxy primer over that. It nicks very easily, not what I desired for the interior. My PPG dealer gave me some SEM brand self etching primer in a rattle can to try, saying it was more flexible, but I haven't shot a batch of Urethane over it yet. I also have tried a rattle can Rust o leum "Industrial and Marine" primer over the SW rattle can self etching, hoping that the PPG Urethane will not lift it off.

Parts that I wash primed, then Epoxy primed an hour later and top coated perfrom flawlessly: I can't chip it or scratch it very easily. If someone has a rattle can self etching, or rattle can that I can spray over Alodine that a hi solids Urethane will not lift, please let me know.

Art

RV_7A said:

RV9AVIATOR is correct. Mixing SW with 1.5 - 2 parts reducer/catylst is the answer. I also am using a HVLP gun and have found spraying at 90 psi with it mixed thin and the needle open very little works awesome. It looks like the coating the QB comes with from Vans. Very thin and even.
GOOD LUCK!

Jeff

Click to expand...

Maybe that's one of the problems I had...mygun is recommended no higher than 40. OTOH, one poster's solution here was about 10 psi, another about 90 psi.

When it comes to adjusting guns for an optimal spray pattern, there's too much readin' goin' on here.
Forget the "recommended" pressure settings. To get the best atomized pattern possible from an HVLP gun, you should pretty much count on over thinning by around 25% at least and maybe a little more (going to thin isn't good either).

Then to get your best spray pattern, pick a blank spot on a piece of something flat, and spray a test shot. Change pressure and feed and pattern dispersion until you like what you see. Sort of a WYSIWYG sort of thing.

//When it comes to adjusting guns for an optimal spray pattern, there's too much readin' goin' on here.

I wish it were that simple. The reading I've done on it is because the "just point, spray, shoot, adjust" didn't work for me.

It seems to me you've got three areas that all have to be right.... the pressure to the gun, the spray pattern and the fluid flow.

As with any calibration of multiple items, you've got to have a place to start and, more important, you've got to know which to adjust in order to achieve optimum performance. To the extent I've resorted to too much reading, it's because before I can make any adjustments intelligently, I've got to figure out what's causing the problem in the first place.

Look at like a crosswind landing.... the first step is knowing what the aileron and rudders do ... and then you can start with a baseline (neutral) and adjust from there. When you add one, you begin to understand what the other one does and you can begin to come up with a perfect mix.

Now add the third variable and you've got your basic HVLP gun. And, sure, you can start adjusting stuff and see what happens and guess and start adjusting something else. Most everyone I know who has had problems with the HVLP gun and the SW primer has done exactly that.

But without a little more knowledge about the gun, painting is like landing in a crosswind without any clue.

That's why I read. I read as a result of the problem. The problem isn't a result of being more informed.

//Forget the "recommended" pressure settings. To get the best atomized pattern possible from an HVLP gun, you should pretty much count on over thinning by around 25% at least and maybe a little more (going to thin isn't good either).

Where the SW primer is concerned, if the gun isn't set properly 2:1 vs. 1.5:1 isn't going to solve the problem. I know. I've tried. A badly set gun is going to give a crappy paint job.

And I've got the paint job to prove it.

Actually, now that I think of it there's four settings. The pressure regulator at the base of the gun, the fluid flow, the air setting on the gun, and the spray pattern.

Bob Collins said:

Actually, now that I think of it there's four settings. The pressure regulator at the base of the gun, the fluid flow, the air setting on the gun, and the spray pattern.

Click to expand...

You've got that exactly right. There are way more than just a couple of adjustments to make, and that's my point.

It's not that difficult to tell which direction to go with any of those adjustments if you look closely at what a test pattern gives you.
In fact, it's impossible to get a good spray pattern if you rely on the instructions, and you will positively, absolutely, have to adjust outside of recommended settings (or at least to the limits of them in one way or another) to get a good pattern at the right pressure.

You can start with what's in the book, but you won't get a good finish if you believe the book and jump right in because you're not just dealing with the spray pattern, but different materials will behave differently out of the same gun.
Plus, if you change the viscosity of the sprayed material, you start all over from scratch to adjust the gun to spray THAT particular material.
Even spraying the same material, but a different batch thinned differently, will change the rules.

You have to have a really open mind about this and concentrate less on what's "supposed" to be and instead concentrate on what it "needs" to be, and adjust accordingly.
And I'm not even touching on the idea that a person might be trying to make the wrong fluid tip work. There are different size fluid tips for these guns, and changing tips means you start all over again with adjustments. By changing to a larger or smaller orifice, you either make things better, or you can make things worse, but you still won't know unless you base your adjustments on a WYSIWYG test pattern on a solid surface.
If you take a look at the instructions with any gun, you'll note that, while it may mention the availability of various size fluid tips (actually, tip and needle combinations), no different setting recommendations are given for any of the different tip/needle sizes.

I'm afraid I have to stand by my seemingly whimsical suggestion that you put the instructions down and adjust until you like what you see. Granted, my experience in the paint field makes this reasonably simple for me personally, but that's why I recommend not fighting the "instructions" because if the fight is between the painter and instructions, the painter will lose every time.

Here's a hint I can offer: I rarely spray at pressures as high as those recommend because I like better "flow" which leads to better "laydown" which translates to better gloss.
BUT, and a big "but" here, that also means that I change other parameters as well including different settings and mix ratios of the paint.

Personally, my favorite way to paint large areas is NOT with an HVLP gun, but using a 2-quart, pressurized pot. It's quite amazing to see it spray a nice, wet, even pattern of paint over 2 feet from top to bottom of the pattern.
Find how to do THAT in some instruction book.

//You can start with what's in the book, but you won't get a good finish if you believe the book and jump right in because you're not just dealing with the spray pattern, but different materials will behave differently out of the same gun.

Ah, I see what you mean. Yes, I think that's right -- it is for me anyway -- the initial problem was the result of me reading the book...which was pretty lousy to begin with.

Most of the online reading I've done has been pretty interesting; just too cold to try it here right now to see if it works. But basically, it gives me a sense of an order of things to try in the WYSIWYG system.

This link (http://hotrodders.com/kb/body-exterior/articles/spraygun.html) provided me with stuff that made sense. Whether it works or not, I guess we'll see. Heck, it's just primer.

//You have to have a really open mind about this and concentrate less on what's "supposed" to be and instead concentrate on what it "needs" to be, and adjust accordingly.

Good advice!

//Personally, my favorite way to paint large areas is NOT with an HVLP gun, but using a 2-quart, pressurized pot. It's quite amazing to see it spray a nice, wet, even pattern of paint over 2 feet from top to bottom of the pattern.
Find how to do THAT in some instruction book.

I hear this a lot and that's what the person speaking at the VAF-Minnesota forum said too. Fortunately, I just got some pressure pot gun from that air compressor litigation settlement (thanks to Dan Checkoway for that heads u a year or so ago!). I'm anxious to test it out.

Thanks for your help, Vern! You know, we should assemble a list of photos of people's paint attempts on a single page and have you give your opinion on what you would adjust in what order to solve it.

Oh jeez, it took me over a quarter decade to get out of the paint business and now you want to draw me back in.

But ok, I'll bite. It sounds like the making of a game show. As long as it's got something to do with RV's ("on topic"), maybe it won't hurt so bad and bring back all those bad memories of frosted paint from the high humidity, or bugs in the last coat of clear, or a helper dragging an air hose over a freshly painted fender, and ...whooa, stop me before I get dizzy.

painting the outside

When I get finished with the building I would like to paint the plane myself. How bad is the learning curve? I have never painted any thing worthwhile before. I don't want a fancy paint job just one that looks nice.

Thanks
Ryan

Ryan Slater said:

When I get finished with the building I would like to paint the plane myself. How bad is the learning curve? I have never painted any thing worthwhile before. I don't want a fancy paint job just one that looks nice.

Thanks
Ryan

Click to expand...

Like other learned talents, learning curve may vary according to your natural aptitude and how bad you want to do good.
The very best way to start is to find someone who already knows how to do it and let them coach you through the fundamentals. Once you learn the basics with someone's help rather through trial and error, the rest of the details should fall into place reasonably quickly.

While you're not going to get good enough fast enough to go into the painting business (and be able to make any money), you should be able to get good enough early on where you can paint your own plane and have something to be proud of.
Just be sure to put your personal signature on it somewhere, and for that, I recommend a nice sloppy run somewhere where you can point to it and proudly say: "I did that!" Works for me...

I checked out the RV that Joe Schumacher built on the "From the Ground Up" series. There's a little run on the VS. That made me feel good.

Say, I see Ron Alexander has a new book out on painting your own airplane. (http://shop.eaa.org/html/04_books_howto.html?cart_id=). Has anybody read it and would you recommend it?

Hey Ryan. Just look back on page one. That's the second plane I ever painted. The first was a Searey I did 4 years earlier. Those are the only two times I ever painted anything without a brush or rattle can. If I can do it, so can you. You get practice during the primer phase, then you will be ready for the finish coat. There will be an article in next month's KitPlanes Mag featuring how to build a spraybooth. Mine may be featured in it. I used a Citation HVLP unit with fresh air mask. I painted the plane in parts before final assembly using Aerothane from PolyFiber.

Roberta Hegy
RV-7A N2447A

face it, painting is hard to do

I used a Devilbliss Finishline 2 HVLP gun to paint my RV just this last winter. I recommend it if you don't want to send clouds of overspray everywhere. I painted in a hanger with a partial paint booth set up in it.

I did expirement with an old cheapo style gun and I didn't like the overspray, or the way it layed out paint. I didn't spend much time making adjustments to that gun, but it wasn't for me.

Just like other people have said there are a lot of variables to consider requiring little tweaks and adjustments in pressure, volume, and spray pattern. Also guns get dirty, which requires a constant diligence to keep up with that.

Here's some numbers I used. 40lbs pressure at the gun which is probably sixty lbs at the compressor. I used the .04 tip for the AFS topcoat paints. The technical support guys told me to turn up the pressure to the number I wrote above from a lower number (25lbs), which is recommended in the guns instructions. With these numbers I was able to get an even atomized flow.

Good luck

Hi Roberta, the picture looks great, did you have the plane finished when you started painting? I was wondering if I could paint as I go. If I have some down time I would like to paint the empannage.
thanks Ryan

freegespeed said:

I used the .04 tip for the AFS topcoat paints.
Good luck

Click to expand...

How'd you like the AFS paints?

PJ
40032

Hi, Ryan. I painted the plane in pieces before final assembly. Everything was completed and fitted, then removed. I had the wings in for the incidence and root fairing fitup, the empennage was on the fuselage for fitup of the fairing and alignment, and the cowling was all fitted along with the engine baffeling. Everything was off, the engine was covered, and pieces where shuffled in an out of my spray booth for priming and and painting. As parts were finished, they were stored until they could be assembled to the fuselage. I would not recommend painting anything until it is completely done, meaning it has been temporarily mated to it's counterpart for fit, then removed. Otherwise you risk damaging the finish while drilling and fitting parts.

Here are some shots of stages of painting.

Roberta Hegy
RV-7A N2447A