It depends on the product you are spraying and type of gun. The recommended pressure are usually noted on your product p-sheets. For example, the basecoat I use lists 8-10 psi (at the nozzle) for a HLVP gun. By the way, "at the nozzle" is not the inlet pressure.
Confused? You should be if you have never used a HVLP gun before. There is no way to measure "at the nozzle" pressure unless you have a special, high priced, air cap. One gun I have requires 43 psi (inlet) to produce 10 psi (nozzle). Another one requires 55 psi (inlet) to produce 10 psi (nozzle). It depends on the gun.
For a complete repaint (exterior and interior) I would buy:
Uh...how to set spray gun? & also Paint Compatibility questions
Ok, so far so good. Now, I've got this nice little spray gun, HVLP I bought from Harbor Freight, one of the few with the little tank on top that, according to a couple car web sites I visited supposed to put out a big 9 inch to 12 inch spray fan. I'm planning to paint my truck 1 piece at a time, as time permits, and as the neighbors are almost ready to lynch me for this nasty looking primered heap in my driveway. At least they'll have some hope of it looking better then.
Anyhow - lots of screws and stuff on this gun, so WHERE do I start with it? Thanks
And...oh yeah, that idea of a guide coat, doesn't the paint in the rattle can have to be compatible with we spray on? Or the paint we spray on have to be compatible with the original paint on the vehicle? How do we determine compatibility then? Thanks!
One **** will control the tip and another **** will control the fan. If yours has a third **** (which my HB gun does), I believe it controls the flow of paint. We will take the first two, first.
The tip control **** you adjust by backing it almost all the way out (counterclockwise). Then pull the trigger all the way in. Start turning the **** in (clockwise). At some point you will feel the trigger being pushed forward. At this point, turn the **** a 1/2 turn more and stop. The **** is now set correctly and you never adjust it again during your painting session.
The fan control **** is set by spraying some of your material. You adjust it until you get your proper fan spread.
If you have a third **** (like I do), just set it until the gun sprays material. Come to think of it, I don't recall doing much of anything with the ****. I set it a couple of years ago and I haven't touched it since.
The only **** that you might adjust during the painting session is the fan control ****. Sometimes I adjust it to tighten up the spray pattern, to get into an area that can't normally be reached.
You're right, it should be compatible but it's not really a big issue because you will be sanding until the guide coat is gone. The low areas, where the you can see the guide coat, will need additional body work (filler, 2K primer, & etc.) anyways.
BTW, old urethane basecoat makes an excellent guide coat material. A 25% basecoat and 75% reducer mix, dries quick, sands fast, and won't load up your sandpaper.
I usually spray the DP series PPG epoxy based primer on bare treated(etched) and cleaned metal. If I paint, it is the entire panel.
Then build up on filler and once sanded, I lay some evercoat icing and go up the grits to smooth the filler and icing smooth by longboaring in cross hatching
patterns to ensure proper feathering and blending.
You have approx 24 hours to spray any build primer like K36 onto the last coat of epoxy primer....this is the window for best chemical adhesion with a DP primer...and anything to be sprayed over it.
Then begins the K3 build primer and guidecoating wth longboards...the first session of guidecoating I usually do with 180 to cut the build primer down quick.....then subsequent guidecoats ar done with 220...and last one is finished with 400. Thn seal the ******* and prep for shooting paint.
hey, i sanded the trunk of my torino to bare metal with 40 grit , what do i do from here now?. my freind tells me i am not supposed to have any sand paper scratches cause it will show through after the paint job.
also which sealler to start with from bare metal at 40 grit?
91 F150 xlt
69 Torino Coupe
53 Ranch Wagon
Do it correctly and you don't have to worry about scratches in the metal. From where you are at, I would do the following...
Sand the truck again with 80 grit. The idea is to just smooth it up a bit. Do not attempt to sand out any scratch marks. You're probably whining right now. What, another sanding? Just bite the bullet. You are going to sand that vehicle several times before you're done.
Now you have a choice. Either epoxy or self-etch primer. Personally, my choice is epoxy. Once you put epoxy down, there is no rush. The metal is sealed. By the way, PPG recommends epoxy.
Do your bodywork.
Spray epoxy over the areas where you applied filler (aka Bondo).
Spray 2K filler primer over the entire truck. You will probably need 2-3 heavy coats. This is the stuff that will fill in scratch marks and some low areas. Oh ya, I forgot to mention. You will have to sand the entire vehicle if you have exceeded the epoxies topcoat time.
Spray on a guide coat.
Sand entire vehicle and fix areas that need additional work. I use 220 grit during this phase. You may need additional application of 2K primer.
You are now at, your what? Your final sanding, of course. Go over the entire vehicle with 400 grit (600 if you are using a metallic paint). Now you are finally at the paint stage.
There are missing details here but there are lots of people that are willing to help. Feel free to ask.
thanks Aekisu,. i want to paint the whole thing but can only go body part by body part, so far i have sanded down to metal the left rear quarter panel and the trunk now which i still have to do the inside,
could i just remove the trunk and then put epoxy then wait sometime till i do the left fender and so on?
is it possible to seal the metal and wait a few weeks or more ? IF YES HOW LONG CAN I JUST HAVE EPOXY SEALD B4 I DO THE OTHER STAGES.
91 F150 xlt
69 Torino Coupe
53 Ranch Wagon
Last edited by forddytube; 04-30-2004 at 05:50 PM.
That's the great thing about epoxy. You can wait just about as long as you want to. It will keep the moisture off. I would avoid the rain and allowing it to bake in the sun. Just remember, if you exceed the topcoat time (which you will if you are talking about weeks), you need to clean and scratch the epoxy prior to doing any additional paint work.
Oh ya. Make sure you get epoxy designed for direct-to-metal (DTM) application. Apparently some epoxies aren't designed to do that.
Regarding Carlene's last post. After sanding an epoxy primer, applying an acrylic primer surfacer, sanding, can you then apply a polyurethane acrylic enamel? Why would you need another epoxy primer over the primer sealer?
Dennis - he's not talking about the epoxy/filler thing, he's talking about my post #23 on page one of this thread. (I don't know how to link a specific post)
Epoxy, filler, high-build, finsing (Icing-filler), epoxy, final paint is the way I was told by my PPG paint rep to do it. I don't know if the final epoxy is required and maybe it's not even needed, but since I'm using a tinted epoxy close to our color it can't hurt. Could have been a selling point for the paint supplier. I trusted their opinion since the guy that recommended them and who's tax number I buy my supplies under is a "HUGE" customer of theirs.
Carlene and Dennis thanks. I had already read the link a couple times. I started with sand blasted surface, used PPG recommended metal cleaner and prep agents, put on epoxy primer, used a little bondo, shot on primer surfacer, sanded with 320, shot on another coating of primer surfacer, and sanded with 400 then 600. It looks perfect enough for me. So now it appears there are 3 possible next steps. Put on another coat of epoxy, shoot on sealer, or apply color coat which is a metalic paint. If a coat of either epoxy or sealer goes on next, then it seems like that nice surface isn't going to be so nice, and therefore at what point do you clean it back up with another sanding? You aren't supposed to sand the metalic finish, so would it be after a clear coat?
The only thing worse than my knowledge in the painting deparment is my skill with a paint gun. The first spraying of primer surfacer went terribly. The gun must have been too far from the surface and the primer surfacer went on in extremely dry coats. As the color coat application gets closer I am getting more nervous. Mike
Assuming you used a modern 2K surfacer (as opposed to the older 1K lacquer primer), there is no need to apply a sealer before applying the topcoat. Sealers are used to protect the older type of paints from the solvents. 2K does not need the protection.
My first paint job was a metallic paint. Noone told me there was a special challenge to applying a metallic paint. There was a steep learning curve but in the end though, it came out looking like a professional job. You can do the same.
Metallics will mottle (sometimes referred to as tiger-stripping). It is caused by the metallics laying in different directions. When light reflects off the metallics, it gets scattered, resulting in a mottled affect.
Spray metallics as you would any color. After you have applied your final coat, you have one additional step. It's this additional step that eliminates the mottled affect.
Let the final coat flash off for a couple of minutes. Add some extra reducer to the paint remaining in your gun. Now you will apply the over-reduced paint. Hold your spray gun a couple of feet from the surface and apply a mist coat. I normally apply 2 coats in a "X" pattern.
My suggestion is to buy some extra paint and practice on an old hood.
You can not sand a basecoat or single-stage metallic. If you do, you will need to repaint. All sanding and buffing must be done on the clearcoat.
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