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“Basics of Basics” Spray technique
By Brian Martin

A perfect paint job would have a consistent thickness on every square inch of the car, agreed?

To have four coats on the left fender, two on the right, five on the left door and one on the right wouldn’t be right. For consistent color, appearance, and durability you need the thickness (film build) to be consistent.

The closer to a perfect “decal” over the car, the better. However, just by the nature of human beings and their faults this isn’t always the case. If you were to check the “MIL” thickness (there are super accurate digital tools for this) of the average repainted car you would find many different amounts of film build.

More film build is usually found at the meeting point of two panels, like the seam at the door and fender. Think about it, you can’t paint down the whole side of the car in one pass, so you paint the fender with a number of passes of the gun starting at the front top, ending at the rear top, then moving down to the next pass right below that. You do this over and over until the fender is shot. Then you move on to the door, right? What happens right at the seam between the two? You have painted a coat on the fender, AND on the door; you can’t start and stop perfectly at the seam, so right there at that seam you are applying twice the amount of paint. Yep, if you apply three coats on the car, you are applying SIX coats at those seams.

It is very in these days of high solids clears to see a sag running vertically right on the edge of these panels. It will almost look like the panel has a body line going down the folded edge. It is caused by too much film build. Many times this sag isn’t repaired because it almost looks natural there on the edge. But it can be eliminated with a change in spray technique.

Ever seen a candy paint job that is darker at the seams? This was caused be the very thing I just described.

A classic example of this can be found on many early VW bugs. The hood is triangle shaped, with the front right at the handle being much narrower than the rear. Well, if you paint one side of the hood and then move to the other side it is VERY easy to end up with twice the coats right down at front of the hood. Go look at that point the next time you see an old air cooled bug and you will likely see a sag in the paint right at the bottom of the body line next to the handle.

Understand, this isn’t the end of the world. Most of the time this small discrepancy is acceptable. My point is, the closer to perfect, the better.

I was taught this simple spray technique about a hundred years ago (seems like that) at one of my first jobs. We were shooting lacquer completes. Sometimes these paint jobs had fifteen or twenty coats of color applied. My mentor at the shop pointed out to me to “Move the dry spot around”. If you didn’t you would end up with a much drier area at each of these seams. Remember, this was lacquer, if you have not shot it, it dried FAST. The overspray off the end of the spray pattern could produce a LOT of dryness. So if you did this coat after coat it would build up pretty bad.

After shooting a zillion coats of lacquer that way, I continued the practice. I have used this technique all these years with primers, sealers, colors, and clears, urethanes, epoxies, enamels, all with great success. It just makes sense to me to try to get that perfect “decal” over the panels. I pay particular attention to doing this when I do edges, there is one pet peeve of mine, one thing that boils my blood is seeing fender edges under the wheel well with dry spots or worse yet, no paint! EVERY SINGLE SQUARE INCH of panel should have good coverage. I don’t care if it is going to be hidden with a bumper, under a vinyl top, unseen after the fender or what ever is bolted on, I don’t care, EVERY SINGLE SQUARE INCH gets covered, if it was intended to be so.

Here is an example of the technique. You don’t have to do exactly as I have in the drawings, these are just suggestions. Adjust this concept to your particular needs. The basic point is to not start and stop at the same point every coat.

PLEASE NOTE: The direction of the lines in the drawing DO NOT mean you are to spray the paint in that angle, that was only done to more clearly show the starting and stopping points. To spray in this fashion isn’t out of the question though; I will find myself doing that as well, to get a more even coat. But that is only in particular places with particular needs.

[img]http://members.aol.com/goodstuff53/movethedryspot.jpg[/img]

Thanks for the Tip! (thumbs up)

is that a cordoba with the fake convertable top?

i encourage folks to do their own painting when it's practical. while it does take a fair amount of practice, this is one area where people can, in time, do a pretty reasonable job. these are, after all, old trucks that were painted solid colors, and with enamel paint.

to practice, get old sheetmetal parts from a junkyard or behind a body shop. since they are practice pieces they need not be perfect. what martin tells us (and is right on the money) is we are looking for the same thickness of paint at the taillights as at the headlights, with as little variation as possible. remember constant movement when painting, and that the gun be moving before, and after depressing the trigger.

constant, even movement, and always hold the gun at a given distance. it should NEVER be thicker in the middle of a pass, and lighter at the ends. this takes alittle practice.

one thing i do is to never stop in the same place, either above or below the previous pass. when shooting a finish coat i try to walk the entire distance, front to back, of the vehicle. it's alittle difficult to keep the gun moving at the same speed and distance from the work, but again, with practice, it can for the most part be done. for the roof area i make alittle scaffold i can erect just high enough to allow me to paint from front to back without stopping, and allows for even paint thickness in the middle of the roof. this little trick i learned from painting big trucks and shooting some rather nasty stuff called imron.

a good idea is for you to paint EVERYTHING, even from a rattle can, like you were painting the most expensive car in the world. even smooth coats with equal coverage, and a nice gloss without runs when complete.

good topic martin, and i bet it will help alot of folks.

Good Stuff Kool. The one thing I hate to see someone try without a lot of experiance is painting down the whole side. Walking down the side of a car is a recipe for desaster for your average home hobbiest. But you bring up a lot of very good points on keeping the gun at an even distance. This is why I will include (at no extra cost ) another article explaining this part of spraying. You did a great job of it yourself. But I have a little more that may be of help to someone.

And guys Kool is right on the money about practice and where to get practice panels. Go to a body shop, they are HAPPY to give you some panels out of thier sheet metal bin. I work at a very large shop so it is a little different than some, but we have a bin that is about 30x10x10 that we will FILL up in a month or two. Believe me, don't be bashful, shops are happy to give you a nicely painted (super easy to work with at home) 2004 Chevy pickup fender or something like that. They are great for practice.

And, check with the paint store you are getting your paint from. They usually have a bunch of "mismatched" paint they are HAPPY to let go for a song. Tell them what you want to do with it, they will certainly (if they have a brain in their head) will give you a super deal, maybe even free. You may need to buy some hardener or reducer but that is fine, every check on tuition at a trade school?

Hey Bent, darn tootin, with "rich Corinthean leather" no less.

Brian

Basics of gun travel

The sequence of how you walk around a car painting is really “learned”. If you understand the “why” the “how” will come to you.

I started out painting lacquer completes on restorations in the late seventies. My boss preached a lot of tricks and they have proven to hold up over the years.

On a 15 coat lacquer job you definitely didn't want the dry spot in the same place with every coat, so you have to “move it around” he would say. This has always stuck in my head, move the dry spot around or "chase" it. I start at a different point every coat, so that dry spot is moved, every coat. As you enter and exit a panel, you must do this little "dance" with the dry spot.... Coaxing it along from one panel to the next.

Doing the roof first lets it stay wet while you go on. If you do the hood first and then the roof, the overspray from the roof falls on the hood and "dries" it. This is what happens with every panel; it is just on a smaller order.

As far as "carrying" the gun, this is a long learned skill. But the basis is the idea that you are a ROBOT and you are to hold the gun a certain distance from the surface of the panel. This distance MUST BE maintained. The height is the same way, as you go across the panel (commonly called "down" the panel even though you are not going "down" but across) the height MUST BE maintained. So your overlap % is maintained. These two things are what keep each coat uniform with an equal/even about of product being applied.

So with this in mind what ever YOU do to "make" the gun do this is up to you.
Some of us look like a Ballerina painting, others a mechanical robot.

All the time I spent boxing helps me a bunch. I stay on the balls of my feet with knees bent and carry the gun out in front of me. Everything that happens between the gun and the soles of my feet is a fluid motion. I watch the paint hitting the surface, and with my peripheral vision look ahead for where the gun has to go.

You need to separate the body and the gun and think about "where" the gun needs to be, your body will make it go there.

I remember watching a pinstriper (who was a childhood friends dad) stripe a very long front engine rail, he just walked backwards down the length of it with his hand flowing over the top of the rails in the same fashion I have talked about here. His Dagger brush left PERFECT stripes, it was amazing. Well holding a spray gun is no different. After a while you can walk down a 40' semi trailer and the pass you are spraying looks like that pinstripe!

Practice on a car with no paint, just move up and down (across) the panels holding the gun that perfect distance. If you waver, it isn't the end of the world, there are many factors to "makeup" for your "mistakes" but the closer you maintain the gun to perfection the better your work will be.

that's right become the panel!(seriously)

again martin, right on the money. martin spoke of coverage. for me, that's as close to a perfect 50% as possible. that means each pass with the gun covers 50% of the last one. this ensures equality in the overall job. the last coat of paint is mostly thinner to add gloss to the final job. you MUST adjust speed accordingly, or risk a run or sag on the very last coat of paint. in short, be prepared to speed up the last coat.

remember, we long longer shoot laquer for the most part. old school guys who learned to shoot laquer properly are pretty well artist in my opinion, and i confess i have done my share, but i find the newer enamels much easier to deal with.

that said. (this is important kids)

you must allow "flash time" between coats with enamel paint. this is not as important with laquer because the stuff is damned near dry as it leaves the gun. not so with enamel paint. it has a much longer drying time, so there's a good chance the paint will not be cured when you shoot the second coat, so, PATIENCE!!!

you can shoot paint alittle too dry, and be ok, just more work for proper coverage, but paint that's too wet is very unforgiving, and forget about "chasing the run" to the bottom of a panel. just look at the thing, then swear at it profusely, and if possible, kick the neighbors cat. time to let everything dry and LIGHTLY sand the run until its gone, wet sand and pick up where you left off.

be patient, wear proper protective clothing and a mask (not one of those silly dust masks, i mean a proper respirator) and prepare yourself for a long commitment to the job. old pros shoot paint in record time, but as i remember, martin titled this topic "basic of basics" so i will hold to that standard.

remember YOU CAN DO THIS!!!! however it takes practice and skill, which you CAN DEVELOP!

for me the test of anything i attempt is to remember that others have done it, and they didn't emerge from the womb knowing how. they also learned.

martin has been on this website for a number of years and has never posted anything that isn't extremely useful and to my knowledge absolutly correct. i may know a thing or two, but i see martin as a master. he's a great source of knowledge, and if you need it, assistance.

speaking only for myself, if i can help you, just ask. i bet martin feels the same.

now get yer [censored] of the seat and go practice! in a short amount of time you will be proud of what you can do.

one last little thing.

safety.

atomized paint and thinners are EXTREMELY flammable. good filtered ventilation, and removing ANY possible source of ignition are IMPERATIVE! THIS INCLUDES YOUR COMPRESSOR, WHICH ARCS INSIDE EVERY TIME IT RUNS. your neighbors will thank you for not blowing your garage off it's foundation, the fire department will thank you for leaving them alone to sleep or watch the game on t.v., and your family will thank you for not killing yourself. you may not be such a prize, but (dammit!) you are all they have.

remember that as paint coats a surface, it coats the lungs and nasal passages. many an old painter has died from cancer of the lung and esophagas. not pretty. besides, nobody has ever been impressed with candy apple bugars.

have fun kids, but be careful.

Great info fellas. What's your opinion on shooting a lighter "tack" coat first when using enamels? Does it help in your experience or should the first coat be shot the same as the rest?

Bob

With an enamel,yes, a urethane, no. The urethane should be applied with all coats looking the same.

Brian

Man, I feel like a kid sitting at the end of a bar eavesdropping on two masters discussing the finer points...

Hey, if I buy a round, will you stay and talk a little longer??

Learning heaps, thanks guys!!

mark.
'51 KY 3100

i didn't speak much of urethane, or any epoxy type paint. this is pretty over the top for alot of beginners. not as easy to work with and the overspray is there forever. it is imperative that you cover anything, and i mean ANYTHING you don't want overspray on. that includes you. i suggest STRONGLY a good respirator, with NEW cartridges, nitrile gloves, and a bunny suit. a thin coat of vaseline on the exposed area of the skin. (face) some protection for the eyes is essential.

paints for fiberglass, (boats, vettes, etc.) fall into this category, as well as paints for big trucks and industrial equipment. these paints are extremely durable, and damned near bulletproof, but are a hazard to health when applying. again, for old trucks, acrylic enamel with a hardener is your friend. that's just my opinion.

Kool, the only think I can add is that if you are spraying Urethanes you really should have a fresh air system and not use a resprirator, they don't protect you. Especially when you have a room full of overspray with little oxygen in the air.

Check out the "Hobby air" system at autobodystore.com for one.

Brian

agreed. however, in the "old days" when i last shot imron i used cartriges that were beyond what was sold in the auto parts. they are called "organics" and filter a much smaller particle. some can filter out poision gasses. we painted in an extremely well ventilated booth, with positive as well as negetive pressure with a waterfall system as well as filters. those are past days as e.p.a. pretty well outlawed the waterfalls. the shop that allowed me to do some of my work eventually closed due to the inability to keep up with technology, and pretty large overhead. a paintbooth large enough to shoot entire tractor-trailer rigs as well as big construction equipment is expensive to build, but the costs of just maintaining the place was pretty large as well. i wasn't a regular employee, but the owner was a friend who got a pretty large "cut " of whatever i did. i was surprised at how much it cost him to operate.

which---

brings us to another point.

disposal of waste products.

leftover thinners/reducers, or paint products are hazardous materials. remember 1 quart of a petroleum product contaminates thousand of gallons of groundwater, so, DON'T BE DUMPIN' STUFF IN A SEWER!. besides, the stuff will explode in a confined space. (longtimes residents of st. louis can tell you about the day the street exploded. the culprit was m.e.k. or methyl ethyl ketone). most cities/counties have a program to allow you to dispose of your shop wastes. you as a taxpayer pay for these programs, so why not use them? besides that, i happen to have a well instead of city water. i don't think i want to drink your paint job.

in conclusion, as usual martin is correct. remember that most of my experiance is from years ago, and knowledge, as well as technology has changed. i remember seeing old "leather lung" guys not using any sort of protection. not one of them i knew back then is alive today. NOT ONE!

if any of you are even considering one day doing your own paint work, you would be wise to print out what martin has posted here and keep it for future reference. the information he has given is up to date, correct, and worth thousands of dollars to you. this is information for a lifetime, and it was free to you.

quite a gift really.

thanks to you martin.

dave

One thing I would toss in the discussion. You might practice your gun movement to see how you are going to get around all those rounded surfaces (easier on the 67-72 slab siders) and think about that movement right before you paint your truck and also see where your hose is going to go. The robot will be highly upset if its hose fouls the paint job. I have to unwind/unwrap my hose after each coat. (get the kinks out)

Also with any paint job - you will spend a lot more time in prep and clean up of your tools than actual spray time. The paint job really is only about as good as the prep job. If your panels and surfaces are smooth and clean (tack rag) then your paint will lay on there correctly.

Gravity feed guns are ok for panels, but a remote tank is really nice for frames and fender wells where you can't turn the gravity feed gun upside down. Remote tanks have pressure heads and the head can be snaked around all over the place. However those hoses and tanks are more trouble to clean, and the gravity gun uses almost all your paint. HVLPs spit out the paint and don't seem to paint quite as well as the old high pressure guns, but, material transfer is so much better than you'll use way less paint. And you get way less overspray and noxious chemicals floating about.

Its also easier to get a consistent paint job when the vehicle is dissassembled and you can paint various bits flat on saw horses (mind that hose though). Just be really carefull putting it back together. Then you can robot over the panels and not worry about chasing the dry spot or overspray, and with a flat panel, sags are far less likely to occur.

Then again, these guys know far more about it than I do, but I thought I'd contribute my ignorance. I learned painting motorcycles which (other than tanks) are far easier to work with.

And finally, remember, a vehicle won't drive right till it has some kind of scratch or minor imperfection. (moral here - unless this is a museum piece expect a bit of wear and tear and then don't go ape when it happens)

I have found that most restoration paint jobs are probably considerably better than what the factory could do and that some car judging has gotten to the point that if you don't have sags in the paint on under curved surfaces where the factory did it, then you'll lose points! And that's because the quality of restorations are so fine that there is little else to judge a vehicle on.

It's also why I am very pragmatic about my paint jobs and don't do concours work. So after saying that, perhaps you can gauge that info against the rest of this post.

great info guys

Speaking of which, I just found a big drip on the door frame on my 72 truck in the original truck color - that funky medium olive green. Makes me feel better about my paintin!