block sanding blues

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mac daddy mopar

mac daddy mopar

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I'm block sanding my scamp, and every where I used spot putty it shows up in the flat black, I'm using 1000 wet dry paper, it's smooth as glass put as soon as the paint hits you can see every spot,](*,) what can I put down to stop these spots from showing up like uninvited inlaws at a bbq:dontknow:
any ideals? thanks mark
 
The only thing to do is when you've finished, recoat the car and gently give it a hand sanding with your 1000 grit before paint, OR coat the car with a sealer to give uniform color before base coat.
 
Sounds like you've used a lacquer primer surfacer, or some other thin mixture.......They have very little "solids" and tend to sand off very quickly.......If you want the problem solved for good, after you've finished with your sanding, spray the car with a 2 stage (2K) primer......It will NOT shrink, and it's very thick compared to regular primer surfacers.

Kinda' like concrete compared to cardboard in durability.
 
Are you painting directly over the spot putty? What kind of spot putty are you using? If its the old type in a tube I would stop using it. Spot putty tends to shrink like crazy. Also what sounds like is happening is the spot putty is soaking your paint in. You need something in between the spot putty and paint like a good epoxy primer or good primer surfacer as stated above.
 
P.S. 1000 grit is very fine, you can actually polish 1000 grit scratches out with compound. If you are using a epoxy sealer and then your paint 320-400 grit would be a better option. A car doesn't have to be "smooth" it has to be straight.... and you need mechanical adhesion in the form of a good sand scratch. I would find it hard to trust 1000 grit to hold paint on a vehicle. You can clear coat over 600 grit without seeing the sand scratches.
 
will do, I want this thing right the first time, I was using flat black primer spray bombs while I'm block sanding, and the spots would just keep showing up, thanks for the advice:salute: any word on your car yet? I've been walking the floor right along with you, I'll tell my transport nightmare after you get your car, keep us posted on it, again thank you, mark
 
67Dart440GT said:
P.S. 1000 grit is very fine, you can actually polish 1000 grit scratches out with compound. If you are using a epoxy sealer and then your paint 320-400 grit would be a better option. A car doesn't have to be "smooth" it has to be straight.... and you need mechanical adhesion in the form of a good sand scratch. I would find it hard to trust 1000 grit to hold paint on a vehicle. You can clear coat over 600 grit without seeing the sand scratches.
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learn something new everyday, I was under the impression it needed to be smooth as well as straight, thank you:notworth:
 
dont use spot putty

67Dart440GT said:
Are you painting directly over the spot putty? What kind of spot putty are you using? If its the old type in a tube I would stop using it. Spot putty tends to shrink like crazy. Also what sounds like is happening is the spot putty is soaking your paint in. You need something in between the spot putty and paint like a good epoxy primer or good primer surfacer as stated above.
Click to expand...
 
I really have to agree, but I know it's already on the car.......it just takes a LOT more work with the spot putty since it shrinks so much.......just when you think you have a scratch filled, it shows up again...and again, and again......

At any rate, the 2K will solve all of your problems.
 
spot putty is fine as long as its the good stuff and it should only be put on in thin coats because certain spot putties tend to crack while drying if applied thick.

Or what I like to use is bondo GOLD ....its a softer "frothier" bondo that applies nice and smooth but still with the solid finish of bondo after curing.

to knock bondo down I would use some 80 and 120 grit paper.

then go over it and smooth it off with some 220 or skip over to 320 grit.

I use 400 and or 600 for final sanding.

if you want to do it "right" than you need to stop with the rattle cans.....because its not the "right way" to get a nice looking paint job.

you can pick up a gallon of high build sandable primer from your local parts store for around $50.00

reduce it down 1to1 with lacquer thinner and spray the car down with it.

then go back over it all with 400 or 600 and knock it down smooth.

Then you need to spray your sealer and directly after spraying your sealer you need to spray your color and directly after that you need to spray your clear if your doing base clear.

as said above you do not want to sand with 1000 grit....when I wet sand and buff paint AFTER the car has been painted and clear...I normally START with 800 and work my way up to 2200 grit.....and these grits are pretty much meant for polishing!.

1000 grit is to fine and will smooth the surface off to much and when paint is applied it will sit on top of the sanded surface.....where as if it was a course grit ....the paint would seep down into any sand scratch grooves and adhere to the surface you are painting.

good luck and hope some of this helps
 
thank you all, I was using the spray bombs as a guide coat, and putting the spot putty on thin as possible, as I beat most of the dents out of the car, I'm trying to have as little putty as I can on this car:cheers: again thank you all, I'd be as lost as last years easter egg without you:notworth::notworth::notworth:
 
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