my adventures in painting the car thread, DONE! Some final thoughts... Options

[Andyrew]

Flash time starts from when the paint first leaves the gun. If it takes 10 mins to get around the car that's 5 mins to wait for a 15 min flash time.

Typically just enough time to prep the gun for another coat and maybe step out for fresh air.

[914 RZ-1]

I just to-read this and noticed that some people told me to go 30psi at the gun. The engine lid turned out really well because I think I had the gun pressure turned up. I can't remember, though. (IMG:style_emoticons/default/headbang.gif)
I have the hoods to repaint so I will try increasing the pressure for one of those and see how it turns out. Stay tuned!

In the meantime I have sanded the car body down with 400 grit and "prep and wash". I sanded the "mountains" down a bit, but not all the way. I want to leave me some paint for sanding later. I figure I'll fill in the "valleys" (and make the "mountains" taller), but that will give me some material to sand off. Thoughts on this?

I'm hoping the paint will go on smoother and I will only have to sand with 1000 grit and up.

[Literati914]

As far as the paint mix, only do what the tech sheets call for, for your particular paint on the air psi and mix ratios. Well meaning people will tell you what works for them but they're probably using a different brand etc, so it's not necessarily pertinent info.

I recently painted my '71 Volvo 1800E with single stage.. and started wet sanding with 1000, didn't work so I (somewhat fearfully) dropped to 800grit as my starting paper - and all turned out just fine. Just antidotal but if there's enough paint laid down, shouldn't be a problem.

[Andyrew]

I think I spray at 20-25psi. With the nozzle a stretched hands width (pinkie to thumb) from the surface. Fan the spray pattern for a consistent spray with 12-18" coverage. Moving at a slow walking pace, if I spray a whole side I walk leg over leg facing the panel and keep my body loose but my arm semi rigid trying to keep a horizontal line over the panel and the depth consistent.

You want to sand the body perfectly flat with 400. You dont want any valleys or else they will transfer to the final finish. The smoother it is prior to final paint the smoother your final spray is.

[burton73]

I think I spray at 20-25psi. With the nozzle a stretched hands width (pinkie to thumb) from the surface. Fan the spray pattern for a consistent spray with 12-18" coverage. Moving at a slow walking pace, if I spray a whole side I walk leg over leg facing the panel and keep my body loose but my arm semi rigid trying to keep a horizontal line over the panel and the depth consistent.

You want to sand the body perfectly flat with 400. You dont want any valleys or else they will transfer to the final finish. The smoother it is prior to final paint the smoother your final spray is.

(IMG:style_emoticons/default/agree.gif)

but you need to get it right at your house. Everone and each set up is different Air flow at you house may be different than my house

Bob B

You want to sand the body perfectly flat with 400. You dont want any valleys or else they will transfer to the final finish. The smoother it is prior to final paint the smoother your final spray is.

Hear this over and over

But you need to get it right at your house. Everyone and each set up is different Air flow at you house may be different than my house

[914 RZ-1]

Here's the latest:

Still a bit of orange peel. However I think I figured it out this time. I would test the gun with a quick burst and the gauge would read 30psi. However, when I pressed and held it the pressure would drop. I re-adjusted the air flow knob. The air flow got quieter and sounded different. I discovered this while cleaning the gun. I really thought I had this dialed in before but apparently not! (IMG:style_emoticons/default/headbang.gif) What's interesting is the parts I sprayed quickly were turning out pretty good, like this headlight cover. It has a nice, smooth coat. That was because the pressure was higher:


The good news is the body is ready to be re-sprayed, so I can apply what I've learned. The bad news is I need to sand and re-spray the hoods and doors. At least they will have lots of paint on them! It will also give me a chance to make sure I've got it this time. I only have a little less than a quart of paint left, too.

[914 RZ-1]

One other thing: how long are the face mask filters supposed to last? I get about 2 sessions, and on the 2nd or 3rd one start to smell and taste paint. It never fails to happen as I'm starting to paint. Any way to tell when they are about to go bad? Maybe I should have an extra set standing by.

I'm using 3M 60923 (organic vapor/acid gas cartridge/P100) filters.

[Andyrew]

Primer about 20 sessions. Not much VOC in the air. Paint, I buy a new harbor freight dual cartrage mask for every full spray session. If I'm just spraying a hood I'll reuse an old one.

[porschetub]

Brave move going to that system for DIY newbie,currently repainting a Golf in PPG Alpine white,prep work is 95% and after that just lay it on ..if it go's wrong just block it back and go again,sand your final basecoat and lay plenty of clear over the top,even if a bit orange peel it will sand and buff out,easy system.
I always lay down a thin basecoat,and see if I have any solvent pop or unfilled stone chips ...there always is some work with spot putty.
IMO leave the clever paints to the pro's or people with garage paint sheds ,fans,spray suits,expensive resporators and folks that don't live too close (IMG:style_emoticons/default/lol-2.gif) (IMG:style_emoticons/default/lol-2.gif) .
DIY myself but have done many cars and boats.

[914 RZ-1]

So my a-hole neighbor called the HOA, the city and the AQMD. He didn't even talk to me first! Part of my "paint booth" (really just a cover to keep paint off the stuff in the garage and dust off the car) was in the driveway for about 2-3 days. It looked like crap, but I wanted to make sure I was done before I dismantled it. I received a letter from the HOA to clean it up. The neighbor also evidently complained about some plants and me working on my car in the driveway. I took care of all that (my driveway is sloped, so I don't work on them in the driveway). The city just told me to get rid of the wood and plastic structure in my driveway. The inspector said he just saw debris, but no painting. He told me I can paint in garage. He also told me the AQMD was called. We cleaned it up and all is cool. I looked up the AQMD rules and it appears HVLP spayers are exempt and I can spray up to 3 gallons a day. Take that, a-hole neighbor! I have yet to hear from the AQMD, probably because I'm exempt.
If you decide to do what I did, just be aware. Talk to your neighbors. All my other neighbors are cool with what I'm doing. I just have one, maybe 2, coats left them I'm done.

[bbrock]

That right there is why I live in the boonies, but even 20 acres doesn't make you immune. I have a neighbor who repairs and restores cars (was working on a Model T last time I was over there). A couple years ago, another neighbor who lives at least a mile away got a bur up his ass about all the junk cars on my neighbor's lot. He did have a lot of them, but the only way you could tell was by looking on Google Earth, or climbing to the very top of my property which looks down on his. So said neighbor starts emailing around trying to convince all everyone in the area that the junk cars will illegal and encouraging everyone to file a complaint. Then he threw in that because the guy had a restoration shop, that he must be dumping paint and other chemicals into the creek behind his shop. Ridiculous. I'm the only one with a view of his shop and never saw such a thing. Plus, the guy is a bit of an environmentalist. As for the junk cars, I looked up the rules and despite him having about 40 cars on his lot, he was in full compliance with the law (which mainly just states they can't be near a stream or visible from a public road. He was in the process of getting rid of most of them anyway. However, my single 914 that had been rotting in clear view of the road was definitely in violation! Anyway, despite protests from all of the neighbors who live nearby, enough complaints were made that the DEQ sent a guy out. He found no violations and the whole thing died down. But boy what a way to sour neighbor relations!

I'm glad you got squared away. (IMG:style_emoticons/default/beerchug.gif)

[914 RZ-1]

So, I'm still getting some orange peel. I thought I could sand it out. I'm not sure what I'm doing wrong.

QUESTION 1:
In theory, I paint the 1st coat with orange peel. Then the 2nd coat goes on. It fills the "valleys" in addition to adding to the "mountains". I should be able to sand the taller mountains down and get a smooth finish, correct?



QUESTION 2:
This is probably related to question 1. I'm getting small pinholes in a really shiny field of smoothness after I sand with 800-1000, then polish. I'm guessing these are the bottoms of the "valleys". I'm thinking I'm not sanding down far enough or not using the right grit sandpaper (I start with 800 or 1000 and wetsand it) or I'm not polishing it enough. I use Chemical Guys V32, then V-36 with a Torq X. I let the polisher spin and don't press hard (it doesn't spin if I do).

QUESTION 3:
Spraygun at 30psi at the handle gauge, right? How much pressure drop is there to the tip? The tip says 10 psi max. Compressor is set for 90 at the outlet. Is there a range of psi that could work? In other words, does 5 psi make a huge difference?

Any tips, help, etc, would be appreciated. I'm getting tired of sanding out my screwups! I'm also running out of time (and paint!); I start back up at work soon and I also want to be done before my neighbor complains again.

[burton73]

How long are you letting it sit before you color sand it?

There can be fish eyes that can be like craters.

I learned to paint on motorcycle tanks in the late 60s.

Look up these things on UTube and learn.

Bob B

[Andyrew]

1. Yes.

2. Pinholes are typically from something called solvent pop and is a real PITA to get prevent on some paint. I would talk to your paint supplier and describe the issues your having. Make sure you have good filtration of water and that you have adequate ventilation of the materials. What's happening is little bubbles are coming from the first layer and trying to escape but not able to.

3. This should help

https://www.learnautobodyandpaint.com/spray...ssure-settings/

[burton73]

After you color sand, wipe it clean and look at it under a bright light. Any low area will show as shiny. That can be a valley that you did not bring up to the mountain top.



Bob B

[ValcoOscar]

Jeff-

Keep in mind, our current HOT weather pattern is not helping
(IMG:style_emoticons/default/blowtorch.gif) (IMG:style_emoticons/default/blowtorch.gif)

I can't spray certain paint by midday. We paint at night right now.

Brutally hot as of late.

Oscar

[IronHillRestorations]

If you have a contaminant on the surface no amount of paint will fix that, you'll only be making it worse by adding more paint on top.

Practice on something else besides your 914 (IMG:style_emoticons/default/smile.gif)

[914 RZ-1]

Thanks all. Here are my responses:

I'm letting it sit for a week before sanding. The paint supplier told me to wait that long.

I didn't think it was solvent pop causing the pinholes, thanks for pointing that out. I wait 15 minutes between coats; maybe I should just spray one coat, or wait longer.

I wipe the surface down with surface prep (Prepall) right before I spray. My paint area isn't perfectly clean, and I've got a few bugs that have landed in the wet paint. They just sand out. But, for the most part, there doesn't appear to be any evidence of contaminants. One thing I heard over and over was "CLEAN the surface, then clean it again!".

I looked on youtube and elsewhere to learn. I thought I had this down. I painted a hood a few months ago and it looked great. I think I need more specific help pertaining to my situation (the weather, psi, equipment, paint type, etc.). I thought some of you might have some insight, so thanks! (IMG:style_emoticons/default/beerchug.gif)

I think Oscar is right-the weather is not helping. I'm even using high temp reducer and hardener (for 85-100 degree conditions). It was about 85-90 degrees (50% humidity) in the garage when I painted at about 10 am.

I can paint at night, but I think it pisses off my neighbor. I'll try one more coat (early in the morning) on a door at higher psi and see what that does. I'm going to dial this in on the doors and hoods before I do the car body!

[worn]

If you have a contaminant on the surface no amount of paint will fix that, you'll only be making it worse by adding more paint on top.

Practice on something else besides your 914 (IMG:style_emoticons/default/smile.gif)

With paint so pricey, I have to practice on my car. Or perhaps I should say experiment. I am having the same problem as the OP has described, only my conclusion is solvent pop more than orange peal (also potentially OP). I think some of us reason like I do, thinking if I get enough paint on I can just color sand to what I want. Good plan except for when you lay down Swiss cheese for paint.

Also, a supplied air system is very much worth considering. It is an extra hose to drag around, but the paint chemicals are hard on the body. One alternative that looks like a winner is a scuba tank and regulator. eBay or Craig’s should be a help there.

[914GT]

Don’t overlook the quality of your compressed air if you’re having flaws in your finish. A filter/regulator mounted right at the compressor tank with a hose to your spray gun is likely not enough to eliminate moisture and oil that can spit out and cause fisheyes or what might be blamed on solvent pop. I don’t know what you have for a compressed air system but it’s important to trap the water and oil that can really screw up an otherwise nice paint job.