Can these defects be fixed by wet sanding? Runs and dust/dot

Discuss anything after that final masking comes off.

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PostPosted: Mon Dec 07, 2015 1:28 am
Hey all,

Second time painting a car and I am happy with the overall result, although I have some issues with my clear coat.

The basecoat went down well, nice and flat and even.

But my clear coat, from my understanding has lots of dust in it, quite a few runs and some werid defects.

I am not sure what happened, but i am hoping this can be fixed in the detail stage of my work (sanding and polishing).

Can these defects be fixed? They are in almost every panel bar my A Pillar/Windscreen surround.

I sprayed in a approx 30C degree day, was a bit humid, my flash times would have been about 10 minutes but I laid the clear on quite heavy. 3 coats in total.

I did not time the flash time, but by the time I worked my way around to all the other panels it should have been at least 10 minutes, as it took about 2 hours to spray the clear. I did the body of the car, bonnet, doors, fenders and front bumper.

Have some panels left to go, but if this cannot be fixed, I would like to try and find out what i did wrong so i will not repeat the same mistake.

They look like tiny little craters, some are dust/bugs, the obvious massive runs, but lots of little craters. I am starting to fear a job well done has turned into a nightmare. :shocked:

Keen to know every bodies thoughts.

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PostPosted: Mon Dec 07, 2015 9:27 am
The first three pictures can be fixed with very careful sanding.
You can try putting masking tape over the run areas and then use a hard block to sand down just the runs through the tape. The masking tape will help protect the thinner surrounding areas.
Other option is to very carefully shave just the runs with a singled edged razor by scraping the top of the run until almost level with the surface.

That last few look like contamination or water in the paint. Depending on the depth of those craters you should be able to sand them out.

Sometimes you are better to sand the entire car and shoot another coat or two of clear.

Just a note: when spraying paint flash times are critical. Consider the suggested times as MINIMUMS.
You should check your clear coat by touching a spot on your masking tape. If it sticks to your glove or produces a string of clear, you need to wait longer.
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PostPosted: Mon Dec 07, 2015 3:56 pm
'68 Coronet R/T wrote:Just a note: when spraying paint flash times are critical. Consider the suggested times as MINIMUMS.
You should check your clear coat by touching a spot on your masking tape. If it sticks to your glove or produces a string of clear, you need to wait longer.


I thought if you touched the taped and pulled you finger off and the tape stayed stuck, it was ready for another coat and if your finger comes right off then its too wet for another coat?

OP,that is an awful lot of runs, for the crates sand them flat if you have enough clear there and they should come out. if you respray that panel with clear, make sure they're all flat of they'll always be visible, has happened to me before. trying to spray more over it doesn't help.
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PostPosted: Mon Dec 07, 2015 4:16 pm
Serf27 wrote:I thought if you touched the taped and pulled you finger off and the tape stayed stuck, it was ready for another coat and if your finger comes right off then its too wet for another coat?


If your masking tape comes off that easy you are in trouble already. :wink:

You want to be able to lightly touch the clear where it will leave a print but not be too sticky. Obviously if your finger pushes through the clear to the tape its too wet.

Rushing the flash times will get you runs and other problems.
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PostPosted: Mon Dec 07, 2015 5:15 pm
'68 Coronet R/T wrote:
If your masking tape comes off that easy you are in trouble already. :wink:

You want to be able to lightly touch the clear where it will leave a print but not be too sticky. Obviously if your finger pushes through the clear to the tape its too wet.

Rushing the flash times will get you runs and other problems.


Oops, sorry, i meant if the tape wants to lift with your finger, not if the tape lifts up off of the car. :knockout:
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PostPosted: Mon Dec 07, 2015 5:21 pm
After reading about the causes for this kind of contamination, I believe it is water in my lines.

Still to confirm, but the signs were there and I ignored them.

Is it possible to touch up the craters?

I have seen some people dab small drops of clear onto them then later sand them out. Though this is while the paint is still drying.

Mine has been painted for about 36 hours now....

I really hope I can sand them out, what grit should I start at for defects?

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PostPosted: Mon Dec 07, 2015 5:34 pm
could be water in the line, are you using an inline filter right before the APR that goes into the gun?

It could also be contamination in your gun or improper cleaning of the panels.
since it looks like you only had crates on that panel, may have been improper cleaning or flash time of solvents on that panel.
First time i had craters on everything i painted it was because i used the wrong soap to wash the car and my gun was internally dirty.
Other cars with proper cleaner I have had the craters only on some areas (3 areas) and i believe since it was only those areas it was improper flash time or oils on that part of the panel.

at this point you should try sanding out the imperfections with 2k grit. you could drop to 1500 but Id stick with 2k.

After the areas are flat, polish the sanded areas and see if the gloss comes back.
looks like you have enough clear on the craters to sand them smooth and not burn through the clear.
If you decide to re clear the panels, my method which i used and works great for me, wash the car with dawn soap, blow the air off with compressed air(also with a filter) and use windex as a wax and grease remover!(or use actual wax and grease remover)
I let the windex flash off for 25-30 min after i wipe it off, then tack rag it and spray.
also clean your gun, the tip, nozzle, and needle very well.
good luck. :goodjob:
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PostPosted: Mon Dec 07, 2015 6:13 pm
Thank you for your advice!

I have a water trap on the compressor itself, and one on my gun before my air reg, It is on every panel that I sprayed horizontal. It really is a horrible feeling knowing that I may need to reclear it.

I don't think it was the flash off times, as when I was spraying it came up straight away, not to mention the abnormal amounts of water being seen in my water trap on the gun.

I guess I just got too excited and kept spraying because I was loving the result. Rookie mistake, and will learn from it.

I am using quite a old air compressor, it might just be on its way out, or the water trap on the compressor end is not doing its job and needs to be replaced. Either or, it basically ruined my job.

The gun is brand new, its a Devilbiss GTI pro Lite, this is the second or third time I have used it.

I had a quick look at my work just before, I can't even really feel some of those fish eyes which I assume is a bad sign. I am not worried about the rookie runs and little dirt nibs, but those fish eyes really ruined it.

Am I able to just reclear the effected area's or should I reshoot everything if it comes to worst case scenario?

I had no fish eyes in my basecoat, my surface was clean. My cleaning was pretty through, i quickly scuffed all the panels with a scuffing paste and washed them off with water the day before. Then applied wax and grease remover prior to spraying (letting it flash off for a decent ammount of time), the basecoat had no fish eyes, but i did notice what looked like water beading from the panel as I was spraying....that was a clear indicator something was wrong. But I kept going.....

Hopefully they will sand out to get me a "acceptable" finish, otherwise I may be in for more work and more money on products.

How long should I wait before I start wet sanding?

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PostPosted: Mon Dec 07, 2015 7:54 pm
If it is on every panel and you prepped the surface correctly, it is some contamination in your gun or the air lines.

Run air through your hose for 2 cycles of the compressor, My compressor is pretty old too but hasn't given me much fish eyes since i started doing everything correctly.

I have also seen people that have long air lines position their line on a high point on the wall or ceiling, it will make it harder for water to travel up the hose and through your gun.(I have never done this so I don't know the effects of it)

I meant flash of times of wax and grease remover but you said you let it flash off for some good time. did you spray the clear coat right after base coat?(with flash time) or was it sprayed on a different day?

Even with a new gun, it should be cleaned. I didn't clean out my new gun when i first started painting and had the fish eyes everywhere just because i was excited to start spraying and didn't clean it.

By water beading do you mean you start seeing droplets of water on the car when you were spraying?

if you can't feel the craters, they have probably settled in more with the drying. see if you can sand them out, if not sand and reclear the panels that were affected.
I'm not sure if you can just reclear sanded down areas, I have never done it.

As for how soon can you start sanding, it depends on the clear you used. My paint supplier says i can start cutting and polishing 24 hours after its applied. But I usually wait 2-3 days just to be on the safe side.

It is hard not to get excited when the panel is being sprayed and a huge difference is taking place, but try to keep the excitement down and focus on getting it down right. Stop if you see any issues and fix them. Then the excitement will be greater at the end when you have little to no imperfections and a good finish!
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PostPosted: Mon Dec 07, 2015 8:02 pm
Serf27 wrote:I meant flash of times of wax and grease remover but you said you let it flash off for some good time. did you spray the clear coat right after base coat?(with flash time) or was it sprayed on a different day?



When I finished putting down my basecoat, I went out of the shed and left it. Would have been a good 15-20 minutes of time between the base and clear.


Serf27 wrote:By water beading do you mean you start seeing droplets of water on the car when you were spraying?



Yeah, when I was spraying my basecoat, I saw drops of water, i just blew them off and thought nothing of it at the time, they did not react to the basecoat in anyway. But I assume this must have been what caused the fish eyes, in my clear.

Serf27 wrote:if you can't feel the craters, they have probably settled in more with the drying. see if you can sand them out, if not sand and reclear the panels that were affected.
I'm not sure if you can just reclear sanded down areas, I have never done it.



This worries me alot, is there any quick fix's I can do? I would like to keep painting the whole panel too a last resort...its not a show car. If the majority of the fish eyes were removed, I would call it day.

Serf27 wrote:It is hard not to get excited when the panel is being sprayed and a huge difference is taking place, but try to keep the excitement down and focus on getting it down right. Stop if you see any issues and fix them. Then the excitement will be greater at the end when you have little to no imperfections and a good finish!


Live and learn, I could probably get away with respraying the majorly effected area's that will be seen easily, but time will tell if they will come out with a sand.
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