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Not a Rational Car Guy
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:bump

Travis, be sure to sticky this.
 

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glad this is here. answered a few questions i had. my mustang is about to go under the gun for a face lift color change
 

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Rebel Of The Sacred Heart
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Discussion Starter #23
One of the most important things when painting is your gun control. To get the best possible results, you need to paint like a robot. Meaning you want to have absolute control over your gun, so you are spraying the same amount of paint over everything. Now the MOST important thing in painting is the surface prep, because ANY imperfections on the panel will be magnified when painted. But second to that is your gun mechanics. Thats what ill talk about this time.


First let me talk a little about the different sprayguns available. You can break down all sprayguns into two basic catagories: Conventional, or a high pressure gun, and HVLP, or a low pressure gun.

Conventional guns have been pretty much replaced by HVLP guns, because HVLP guns have such a better transfer efficiency, and that boils down to alot of paint being wasted by not making it onto the panel using a Conventional gun. So all im going to say about them is that they are yesterdays technology, and if your going to get spray, use a HVLP. Now im sure there will be some people say "I have a such and such convetional gun and i can spray paint great with it". That is not the fact im debating. I have used both and i can get great paint jobs from conventional guns, but i like to make my painting as easy and as cost effective as possible. The HVLP are just a better gun than the old conventional guns in all fronts.



Now for HVLP, or High Volume Low Pressure. They are called HVLP cause say you have 40psi of air coming into the gun, by the time it leaves the gun atomizing the paint, its down to like 10 or 15psi but still has the volume of air that the original 40 psi has. And the lower the psi leaving the gun, the less overspray you will produce. All true hvlp guns will have a 65% or better transfer efficiency(meaning 65% of the paint coming out of the gun makes it to the panel, and the rest is lost through overspray). There are even some HVLP guns when set up correctly that have 80-90% transfer efficiency. Having a gun with a high transfer efficiency equals less spray time and less cost involved in a paint job. MY preference on HVLP guns is Accuspray, but ill say i also love Iwata and Sata guns also. They are all three good brands and it boils down to personal preference. Just remember with a paint gun, the old saying that "you get what you pay for" is a good rule of thumb. Im not saying you cant get good looking paint jobs with a cheaper gun, but the expensive guns are expensive for a reason, its cause they are flat out a better gun and that makes it easier to paint.



Then you can further break those two categories into two more: gravity fed(paint cup on top) and siphon fed(paint cup on bottom). This will also come into a personal prefference thing, but ill say a gravity fed gun is easier to use, clean, and learn with.

I almost always paint with a gravity fed gun, but my favorite and best performing gun i have is a siphon fed. It is an Accuspray #10 Gun, It has the softest and evenest spray pattern i have ever seen, and amazing transfer efficiency. It is also in a sub-group of siphon fed guns, which is a pressurized siphon fed gun. Than means there is an extra air line that puts about 8psi of pressure inside the cup and that forces the paint up into the draw tube.


So now that the guns are kinda out of the way, lets talk about your gun control. A good rule of thumb to follow is the 8X8 rule. That is with your gun 8 inches away from the surface you have a 8 inch wide pattern. You can adjust the width of your pattern using the fan control knob on the gun. You Always want to stay at a ninety degree angle from the panel you are spraying. If your distance is inconsistent(i.e. the distance from the gun to the panel is not the same for every pass you make then you will have thickness variations in your paint film. Thats because the closer you are the thicker the paint will end up on the panel and the further away the thinner the paint film will be. Now you can get away with a little variation in your distance on solid colors, but on a metallic or pearl paint inconsistent distance will wreak havoc, leaving light and dark spots in your base coat.

Next lets talk about your overlap, or how much each pass overlaps the previous pass. Now normally for basecoats you want a 50-60% overlap. For clearcoats I like to use a 65-70% overlap. Again, you might like to have a different % of overlap due to personal preference. Another thing that you need to do is when you make your first pass, say with using a 50% overlap, spray "above" the panel where your only hitting your panel with 50% of your pattern, and on your last pass spray "below" the panel again and so you get your 50% overlap on all passes. If you dont do those two things your top and bottom pass will not have the same thickness as the rest of the panel. and that can come back to bite later, especially with metallics.

So if your spraying metallic basecoat do yourself a favor and use no less than 60% overlap. That will help you reduce tiger stripes in the basecoat. Tiger stripes are the light or dark lines you see in poorly painted paint jobs, and 9 out of 10 times they are cause by to small off overlap or an inconsistent overlap. If you do end up having tiger stripes, you can try and correct them by doing mist coats over the panel. A mist coat is where you widen up the spray pattern, increase the air pressure, and bring the paint gun far away from the panel and just "mist" the basecoat on the panel and that will sometimes hide the tiger stripes. Just be mindful that doing mist coats with mettalics has the potential to make the color lighter than it should be, because you are putting on a light coat and that wont allow the metallic to orientate corectly because there is not enough solvent to let the mettalic flow out right. That is why it is important to just use consistent overlap and not have tiger stripes to begin with. Dont be discouraged if the first time you paint a metallic it looks like crap, especially if you dont have excellent gun control. Bieng able to spray a perfect metallic paint job takes practice, concentration, excellent gun control, and being able to fix a tiger striped paint job is almost an art form. So sometimes it is more plausible for a painter to just start over then try and fix it by using spray tricks.

You also want to have consistent gun speed, or how fast you are moving while making a pass. If you are constantly slowing down and speeding up, it will effect how the paint flows out, especially metallics, which in turn will affect your paint thickness.

Just a little about your fluid tip sizes, and this is just my prefference, so im sure others like it different ways, but this is what i have found to work the best for me.
I like a 1.2-1.3 for base, 1.4 for my clear and sealer, and a 1.8 for primer surfacer. If you can only get one gun and not have a seperate gun for primer, base, sealer, and clearcoat I would recommend a 1.4 tip would be the one to get. Better to have a little bit to big of a tip with your base, than having to small of one and starving the gun when spraying the clear.


So all in all you want to act like a robot when painting, meaning you want everything you do while painting is exactly the same. The only way to really get complete gun control and get to where you are comfortable spraying any and everything is practice practice practice. I have sprayed hundreds of gallons of paint to get my gun control, but now i can say with all confidence there is not a coating i cant spray and make it look good. So when you first start out and its not going how you planned, you just have to keep trying. Noone is a painting master the first time they pick up a gun. Even after all the paint i sprayed, i can usually find something i can learn from on every paint job i do. When you stop learning new things, you are going to limit yourself on how good a job you do. Always try and take something new from every painting experience you have.
 

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Rebel Of The Sacred Heart
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Discussion Starter #24
And here is a little about spraying your basecoat and clearcoat, and how to know when its time to put your next coat on.

Every paint manufacturer will have a set amount of time to wait between coats, it will be something like [email protected] or something along those lines, and wherever you buy your paint should be able to give you a copy of the tech sheet for that product and it will have all that info on it. Just remember when looking at the tech sheet if it is a time at 70 degrees and its not 70 degrees where your painting you have to account for that.

Now with that said I'll tell you how i do it.

Your base coat should be put on as medium coats, meaning it shouldnt look "wet", just almost wet. I know that sounds confusing but you want medium coats of base because it is desinged to be applied in thin coats, unlike clearcoat that is sprayed on "wet" because it is desinged to be put on in thicker coats. After you put on a coat of base, using about a 50-60% overlap with each pass, and it has enough time to flash off(time to dry) the basecoat will have a dull look to it and is dry, completly dry to the touch. Making sure its fully dry is important because you will want to wipe down the entire surface with a tac rag before starting and between every coat of paint(clearcoat excluded, because its still wet when the next coat is applied).

So when your basecoat has a nice dull finish over the whole surface and is dry to the touch its ready to be tac raged off and another coat applied.


Now for the clear coat. Let me start by telling you to put a tac coat of clear on before you apply any wet coats. It will reduce your chances of getting a sag or run in your first coat of clear by giving the clearcoat something with a little profile to it to adhere to, instead of the smoth basecoat. What i mean by tac coat, is a light coat of clear over the entire car. And it truly is a light coat, you are just spraying enough clear on the surface to make it tacky. And then after you spray your tac coat, immediatly start with your first wet coat of clear, because it is such a light coat, by the time you spray one on the whole car it will be dry enough to start your first coat. Then after you have sprayed your wet coat, do the stringy test to see when its time to put the next coat on.

Stringy test: choose an area that is masked off near the painted surface, and press your finger on it. When the clear is still wet it will feel kinda like sticking your finger in some sryup, that is to wet and you need to wait longer. As it starts to dry, it will become stickier and stickier. To the point to where when you press your finger on it and pull it off there will be strings going between your finger and the cleared surface. How i tell when it is time to put the next coat on is when i can press my finger on it and there be many many strings between my finger and the car. Like for example when it first starts "stringing" there might only be two or three strings, but when it is dry enough to put the next coat on , there could be twenty or thirty strings. Do it in a few places around the car. I hope that makes sense, its kinda hard to explain.

With my clear coat on "normal jobs"(one where i am going to be matching the factory orange peel) i put a tac coat and two wet coats of clear. For a car that the owner wants a smooth as glass clearcoat, i do a tac coat and 3 wet coats, that way i know i have enough clear on there to sand it down smooth and still have enough clear thickness that it doesnt make the clearcoat fail down the road. On paint jobs with graphics(or racing stripes) in them i will do a tac coat and 4-5 wet coats of clear because it will take alot more sanding to level the paint down to where you cant feel the graphics edge anymore.


Now I like to have a little more overlap with my clearcoat passes, so i usually use a 70% overlap on my clear coat passes. Except for the tac coat, where i use like a 40-50% overlap, cause your not really trying for a really even coat, just a quick light coat to make it tacky.


The overlaps and process for spraying Kandies is kinda hard to explain, because you really shouldnt even attempt to spray an actual kandy job on a car unless you are absolutely positive you can have exact gun control for the entire job. One tiny little mistake on a kandie job and you have to start all over from scratch. There is no going back and fixing a mess up in a kandie job, its either you do it right the first time or you start over with the basecoat. That is why a good kandie job will cost you 5, 6, 7 thousand dollars and maybe more depending on what base and kandie is involved and the shape of the car being sprayed, because not only are you paying for the paint job you are paying for the skill of the painter that can do a perfect kandie job, and not just any painter can do that.
 

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Short throw
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I have a question Im hoping someone can answer, what type of paint would u suggest If im wanting to custom paint the outside of my side view mirrors. I figured i could just sand it down and use a lot of touch up paint, it doesnt matter if it doesnt match my car im just need black paint. The thing is im not painting the entire thing black only roughly half of it. And I want to do this without using a spray gun, if its possible for it to look good if i didnt.
i want to paint them to look something like this
[/IMG]
 

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I have a question Im hoping someone can answer, what type of paint would u suggest If im wanting to custom paint the outside of my side view mirrors. I figured i could just sand it down and use a lot of touch up paint, it doesnt matter if it doesnt match my car im just need black paint. The thing is im not painting the entire thing black only roughly half of it. And I want to do this without using a spray gun, if its possible for it to look good if i didnt.
i want to paint them to look something like this
[/IMG]
you can probably spray it with a 1k spray can, but it will not last. I would do a flat base with a 2k clear. You can use those prevail aerosol spray bottles. Watch this video and you can basically use pro automotive clears and duplicate this process to your mirrors:


good luck!
 

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