Hello All,
I painted the hood, mirrors and front bumper on our 2007 BMW this past weekend and had a few issues with the hood. The bumper and mirrors turned out absolutely perfect. I mean almost factory perfect.

This is the issues with the hood.

1) After completing the job I noticed the paint/metallic in the very middle of the hood is slightly darker than the rest of the hood (see second image). It's about 8in wide and runs from the front of the hood to the rear of the hood. This is where I overlapped, btw.

2) There is a slight amount of mottling on the right side (driver side) of the hood. This appears as cloud reflections in the image and is very minor. It is only noticeable upon close inspection but it is still an imperfection that I would like some input on.

I was spraying quality PPG Deltron (bc/cc) using a SATA 5000B RP 1.3. Wide open fan, 8in from surface and from 1 1/4 to 2.0 open on fluid knob. I had to make a few minor repairs to the hood so I initially sprayed 3 coats of bc on these areas to cover the primer (see 2nd image). Mainly I just wanted a uniformed color for when I sprayed the entire hood.

I then sprayed the entire hood with bc starting on the driver side and working my way to the middle. I then immediately went around to the passenger side and started spraying from the middle to the driver side. So the line down the very middle is where I essentially overlapped in different directions. In retrospect, I realize this is what caused the line but how do you pros avoid this? I mean do you mist the last coat or two from two feet above the hood in maintaining uniformity with metallics? I sprayed 4 coats of bc to the entire hood as well as 4 coats clear.

I am trying to make the car nice in giving it to our daughter as a hand-me-down. My family doesn't think the issues are a big deal because it just looks like reflections to them and hardly noticeable. It's a little more noticeable than that to me however. I'm meticulous when it comes to such projects and this most definitely wouldn't be acceptable for a professional.

Just fyi, I've painted several dozen vehicles in my lifetime as a hobby but I never painted with metallics. I paint on a daily basis at work using an HVLP so setup and style is not an issue.

I have 1 oz of bc left over and I could purchase 8 more ounces to add to that. So I'd have 17 oz of base coat available for correction. I have extra clear coat on hand because I will be painting the hood on our Escalade soon also.

Anyhow, I realize it will need to be repainted in order to correct this but how? What method do you use to insure uniformity for metallic paints?

God Bless,
Ralph

about all I can tell you is if your seeing mottling your applying the base way to wet. and or to short flash times this also causes the striping you got. if your use to using S/S materials then you need to rethink how to apply base coat, usually a med coat is good. like if your spraying black over tan primer or any colors your first coat of base doesn't cover, you should see the primer. your not trying to get full wet coverage on the first coat, and maybe not the second ether.
Jay D.

Hey Jay,
I don't think it was an issue with spraying the base coat to heavy. In fact I initially sprayed 3 coats over the primer alone, in order to get a semi uniform surface; prior to painting the entire hood. I could still see the primer after this but I was confident the full coats would cover it at that point.

I then sprayed 4 coats of base over the entire hood. I could still barely make out the primer even after the 1st full coat and possibly the 2nd coat also. I then increased the fluid output slightly from 1 1/4 turns open to 1 1/2 turns open for the last two coats.

I spray pretty quick so the base really was never wet, so to say. In fact, even with the gun set to 2.0 turns open on the fluid for the clear coat I never considered it wet. I really could have increased the fluid or slowed down slightly on my last coat of clear but it still turned out perfectly.

I've gotten some input from a few other painters and the issue is, I should have applied a "mist" coat for the last coat or two of base. Whereas I spray quickly and further away from the surface. That would have blended the silver metallic, which apparently is a real challenge, much better in their opinion. I just kept spraying methodically 8in from the surface and with a 60% overlap on the bc and that was my mistake.


God Bless,
Ralph

Just chalk it up to a "learning experience" and make it a "do over" or move on. I joined here 16 years ago specifically to get over my fear of working with metallics and further candies. Guys here pointed me in the right directions....stumbled over some test stuff....and it was like 4 months later I was doing not only metallic but those elusive candy effects as well. Just lighten up on yourself and lose that word "meticulous" for awhile. I picked up refrigerator doors, old fenders, hoods, decks, etc., and used those to figure things out. Paint jobbers will always have some odds and ends base colors they sell cheap for practice as well.

first of all there are a lot of variables that can cause the problem your having. you might try the mist coat, your going to want to do it wile the base is still wet. I've use the mist coat technique with S/S material with good success. but really never needed with base coat, this is one of the variables good quality base coat. I've used some that were almost impossible to get on right and I've used some that a blind man could spray good. also to note, you sprayed 7 coats of base a base that is one of the best covering colors out there. what happened? my guess is still to wet and to fast you should be letting it flash 20-30 min. between coats. the mottling COULD have come form a heavy first coat of clear to soon on the base, to short of flash time on the base. i'm really nearly at a loss here and hoping someone else might have some ideas.
Jay D.

UPDATE:

I apologize for being so slow in updating my results but here it goes.

As stated previous, when I painted the hood on our BMW I ended up with a faint skunk line down the center. I received a lot of feedback but in the end I concluded the issue simply occurred because I overlapped to much in the middle. I had always painted with solid colors so I never had such an issue. Metallic colors are obviously less forgiving and take a little more precision or finesse.

Anyhow, when I repainted the hood I simply made sure my overlap was fully consistent. I applied three correction coats with the first being slightly heavier than the last two. I am happy to say the correction turned out beautifully. I cannot find my before and after pics but when I do I may start a thread on it because the front of the BMW had gotten really ugly due to a degraded 3m clear bra. It's a 2007 BMW with 240k miles on it and looks brand new again.

God Bless,
Ralph

P.S. I will be selling the Sata 5000B RP 1.3 Digital that I purchased for the job if anyone is interested. The gun is like new condition and warrantied to 12-17-2022.

Very,nice....glad you pushed through with it....