clear image?

[preacherman]

The last couple of cars that I have painted have a distorted image to the clear. It is not orange peel, however, the image of an object 3 or 4 feet away is wavy. What could be causing this? I sand with finishing film and buff until all scratches are gone. The clear is nice and smooth but the image in the clear is distorted.

[Robert]

Depending on the grit of finishing film you use, you may still have orange peel. In order to get a really good distinctness of image, you have to start with at least 1000 grit on a firm block. If you want the best clarity you have to start with 800 grit or, only if you have a lot of clear to begin, 600 grit.

Modern paint is so hard that finer grit papers role over the orange peel. I've done tests where I started with 800 at one end of a panel, and sanded about 8 inches, then sanded over that with 1000 and 8 more inches, then 1200 over those and about 8 inches further, etc. all the way up to 2500 at the far end. You could see the difference between each of the steps and the difference between any three of the steps was night and day.

Using the soft interface pad with the finishing film makes it safer but reduces the clarity of the image as well.

Take Care,
Robert

[preacherman]

Thanks Robert, i will try that tomorrow!

[Robert]

Just be careful you don't cut through.

Take Care,
Robert

[Dennis N. Schmidt]

As usual Robert's dead right about this. I found this out while refinishing pianos. It's smooth, it's shinny but it ain't flat. To get things flat in furniture we use a unique sander which is only made by two companies: Stuhr and National Detroit. I've got the National Detroit model 300. These sanders are dual pad straight line sanders and even with these special tools you need to start coarse to really flatten things out. I begin with 600 wet as Robert stated. Sort of hate seeing all of that expensive clear coat being sanded away but it's the price you've got to pay.

[Mooch]

What if the panel isn't straight ?
Mooch

[Robert]

Those big waves give a fun house mirror effect but the clarity is still there, just distorted.

Cutting with a hard block and 600 will sometimes find those waves. It cuts right through to primer if they're high enough. That's why I look at cars very closely before I start colorsanding and then suggest to the painter what I think the car can stand, what grit I think will work for a starting point. Even then, the rule is, I'm as careful as I can be, but since I didn't paint it and I'm trusting that the painter put down enough paint to take the cuts, if I go through, it's not my problem beyond that I don't get paid for the colorsand till it's done. They have to repaint the cut through, I have to re sand and polish, but that's how we break down the liability. If they don't agree to that, I don't do it.

Take Care,
Robert

[Mooch]

Are you saying that with enough clear coat on a panel that isnt straight you can still make it look straight ? Even though maybe the bodywork wasn't done perfect you can color sand it and buff so it looks straight ?
Mooch

[Robert]

No, I'm saying I'll cut through the clear right to the metal if the wave has enough curve to it.

You can still cut the orange peel if there are waves in the body and you'll see a clear but wavy reflection. You can read your watch in reflection but it might look like might look like the Dali model.

[Mooch]

Ok that's what i thought. So how do we know if his panels are straight. he can sand all he wants if they aren't straight he will keep getting the wavey look. Or am I missing something here ?
Mooch

[Len]

If the panel isn't perfect but it's real close you can make it perfect by blocking the clear and polishing. I've only been able to do this a couple times and I don't recommend it but it can be done. Usually a painter can tell if the surface isn't perfect when he's painting and he can lay on another coat or two to aid the sanding and polishing. In most cases poor body work will need to be redone in order to make the painted surface look perfect, it's rare that paint can correct a wave.

[Robert]

If you look closely at the panels before you start sanding, you can see how straight the car is. Sometimes it's a good idea to leave a little orange peel so the waves don't show so much. As the distinctness of image increases, the waves in the image show up more clearly. Sometimes I look at a car and think, "Sheesh, you want me to sand that now? You should have called when there was filler!" Then I cut more gently and try to leave enough distortion/orange peel to hide the waves.

Take Care,
Robert

[Mooch]

That's what I thought .I have always took the time to make sure my work is straight. i was just wondering if maybe I didn't have to . It is a lot of work but clear/coat really does show what's underneath. thanks . Mooch

[reflections7]

But if I use ppg clears I get what sometimes is called urethane shake. Ive seen other people complain about it. I agree it can be sanded out if you start course. Its Not orange peel I am seeing , its like waves all the way down the car but its only happened on a few. The body was flat so I dont know why it did this. I did my brothers Dakota truck. It stays outside ect so I didnt wet sand and buff but when you look down the side its wavy.

[preacherman]

Thanks for ll the help! How much clear is too much? I always put 3 coats on because I know I have to buff. I have a Chevelle coming that I want right and I was wondering how much clear you can put on even if you have to sand it down the next day to put more on. I usually use Dupont 7900S on this type of job but I am open to suggestions. Thanks again!