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Spraying clearcoat over clearcoat

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PostPosted: Wed May 02, 2012 9:29 pm
This is my first post, but I have been reading the posts for quite a while. Greatly appreciate all the great advice taken from this site. I have been working on my daughters 99 camry and in the process of painting. Because of my job I sometimes have to leave with no prior notice and be gone. Now to the problem. The car is two tone with white on top and silver on the bottom 1/4 of the sides. I was painting the white when I got a call to leave so that night I went ahead and put the clearcoat over the white. Now I need to do the silver on the bottom and redo some spots were bugs danced in my clearcoat (late night trying to get done before leaving).
I have sanded out runs in the clearcoat with 1500 sandpaper- wet. Looks good.
I was gone initially three weeks and then gone some more so it has been 5 weeks since I sprayed the clearcoat.
I sanded down the bug spots with 400 (wet) and then used 800 (wet) around that to taper the area. I was planning on spraying these bug areas again with basecoat white and clearcoating the whole panel again.
I sanded the sealer on the bottom (what didn't get painted before) with 400 wet.
After I spray the silver on the bottom I was going to clearcoat the bottom and a third way up the panels to put clear (blend) over the two tone line. I realize that it would have been better to have been able to clear after both basecoat colors were applied.
My big question is what grit sandpaper should I use on the 5 week old clearcoat that will not have additional basecoat applied and were I want to apply more clearcoat. I have read 400, 1000, 1200, 1500, and just scuff it when talking about blending. The tech sheet has a section concerning sanding that says 1200 or finer, but this at the bottom after it talks about drying times. Is it concerning a reapllication or prepping for buffing. I want to make sure I get good adhesion but not leave scratch marks. Your help and advice is greatly appreciated.

Paint:
Sealer - PS21nr
Limco Supreme
Clearcoat
LC-4000

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PostPosted: Thu May 03, 2012 12:11 pm
you can use 800 or 1200 w/d your safe if you use 1200 w/d. if you are flatting the silver on the bottom ,make sure that it is mat and no glossy bits showing,because thats were you will see the scratch marks.it must be even.
fail to prepare ,prepare to fail.

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PostPosted: Thu May 03, 2012 10:37 pm
Thanks - appreciate your help. Wanted to make sure before doing all that sanding.

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PostPosted: Fri May 04, 2012 7:48 am
Ive been told that if you use to fine of a grit like 1200-1500, the clear will not adhere very well, so I never took the chance with the finer grits.
I have always used 600, never had a comeback.......................
"The number of parasites in the USA has now eclipsed the number of productive members of society"


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PostPosted: Fri May 04, 2012 8:21 am
Most body shops only use a gray Scotchbrite on a panel thats blended into, so the clear
is only going over that, that's not much scratch and it holds fine.
That's done everyday, standard procedure.
Fact is, if it's really clean, it'll adhere to a non sanded panel longer than the car will last.

If a panel is being recleared and it has enough on it, I like to use 600 only because
it will level the urethane wave, not just the peel.
I don't do it for adhesion, that's not even an issue (in regards to adhesion).
JC

(It's not custom painting-it's custom sanding)

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PostPosted: Fri May 04, 2012 11:54 am
OldDupontGuy wrote:Ive been told that if you use to fine of a grit like 1200-1500, the clear will not adhere very well, so I never took the chance with the finer grits.
I have always used 600, never had a comeback.......................

who ever told you that needs a kick,When you blend on to another panel you flat with 1200 or 1500,you would not use 600 would you odg.But every one does it different,what works for you might not work for other.i have always used 1200
or 1000 w/d especially on light colors.
fail to prepare ,prepare to fail.

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PostPosted: Fri May 04, 2012 12:42 pm
,,,"who ever told you that needs a kick"

Ha-Ha-Ha,,,why do you say that?
"The number of parasites in the USA has now eclipsed the number of productive members of society"


Capt Rick Hiott.
www.reelfishhead.com

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PostPosted: Fri May 04, 2012 1:25 pm
he needs a kick because he does not no what his talking about,i no you dont 600w/d up a quarter panel to the roof to blend clear coat ,you would use 1000 1200 or 1500w/d.so the clear coat must adhere would you not say old chap.eny way give him a kick from me.
fail to prepare ,prepare to fail.

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PostPosted: Fri May 04, 2012 11:35 pm
Thanks for all the replies. This is why I asked. Someone else had asked this question before in April and JCClARK had pointed out that he sometimes used 400 grit. I wasn't sure if the 5 weeks since application would matter.

I decided to clear the whole car since I found several areas that needed fixing and will have to spray base coat again in those places.

ODG - might call you to go fishing sometime - I found it's cheaper to pay a guide. When you own a boat the cost per fish gets expensive. Guess the same could be said about working on cars. Hobbies are expensive.

Thanks again

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PostPosted: Sat May 05, 2012 2:22 am
The confusion comes because it depends if you're spraying basecoat or not first.

If you're just putting clear over clear you can go as low as 400's.
If you're basecoating,whether that be a full panel or a spot,you have to go finer otherwise your flatting marks may well show up after you've cleared.This is why most of use use an ultra fine scuff pad (light grey) on the clear when we're blending.

If it were me I'd go the scuff pad route.

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