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Discussion Starter #1
the problem im having is trying to get a fender nice and smooth, well strait really.I put filler on the panel and got it what looked to be strait to me, then i sprayed filler primer over that. Each step was blocked sanded using a 16 3/4 inch long board. The problem is that when i look down the fender i still see waves in it. Nothing drastic but you can still notice it. So now do i add more filler or filler primer and keep blocking it? What am i doing wrong?
any help or suggestions would be great....thanks
 

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Probably don't want to use the filler primers....instead, use a black primer (cheap).....spray it lightly and it will reveal where all your errors are....then sand them down 'til the black disappears!

This works well....then finish with a two-stage primer (not cheap!).

If you are expecting a kick *** paint job, you have to do kick *** body work. Don't try the short cuts like filler primer....all it really does is enhance you mistakes.

Hope that helps.

Dean.
 

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Discussion Starter #3
the filler primer(what i call it atleast) stuff im talking about is transtars 2k ez sand acrylic urethane prime (6401ez) which is a primer with "exceptional fill and build characteristics" according to transtar. After that was sprayed on i used the black guide coat and then sanded smooth which looked good after sanding. Now though when i get down level with it and look across it i see a few waves in reflecting differently with the light
 

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Brian Martin,Freelance adviser
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What grit paper are you using to block the filler as well as the primer?

Depending on how much filler (thick) you are working with, you usually need 80 or 120 at the very finest to CUT the filler flat. You can go to 180 after that, but to CUT it you need something that will do just that, CUT.

This goes for the primer as well, 180 or even 120 will CUT the primer flat. You then can go to 220,320 if you have enough primer to block out the 120/180 scratches. If you don't, another application of primer may be needed.

It works well to CUT the filler with coarser paper, to make it FLAT, then a skim coat of filler to finish off the tiny imperfections, and sand that with 120/180. Then the primer is the same way, CUT it with 180 and you will likely go thru here and there, prime it again and then finish it off nice for paint with 320 and how ever finer you plan on going.
 

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Shop Owner And Troll Hunter
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Are you running your long board back and forth, in a line?
You should run it at a 45* angle, and follow the contours
There is actually a skill to using a long board.

Troy

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Discussion Starter #6
thanks for the reply on the sandpaper to use, i think i was using 220 the entire time, if not i know i only started with 150. that was probably my first mistake.
As for the long board, that got me thinking...i did have it turned at an angle , kind of working it sideways, (not completely but around a 45) since the fender has a slight curve from top to bottom i might not of been hitting the highs and lows at the same times, but instead i think i was going up and down with them, probably making them stand out more
 

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I've had a similar problem in the past getting primer/fill coats "flat". Part of the trouble for me is that the primer is too "soft" and I can actually create more waves with block sanding than I eliminate. I also had a problem seeing imperfections really well especially sanding marks left from the heavier grits, even when using different colors of primer as guide coats. A third problem is pin holes in the primer.

My solution in the past has been to use all the normal methods of block sanding primer until I think I have it perfect. Then I shoot a coat of inexpensive black lacquer. Then I scuff sand the lacquer just like you would a final primer coat until there are no visible shiny (unscuffed) spots. If I can't get out all the waves and scratches with one coat, I do a second. It is more expensive (and harder to sand) but for me it really makes the imperfections jump out and seals up the primer pin holes quite well. Once my lacquer coat is looking perfect, I shoot a lacquer tolerant base coat(s) over that and then on to the clear.

I'm sure if I were more experienced with primer and my long block I could get it right, but the lacquer trick just seems to suit me (coming from the old days when all we shot was lacquer or enamel.)

I've never tried it but I'm wondering if John Deere Blitz Black could be used in the same way as the lacquer. It's not shiny but might be a little "harder" than normal primer and seal the scratches and pin holes as well. I might give it a try on my next paint job since lacquer is getting harder to come by.
 
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As Troy pointed out, the long board should be used at about a 45deg angle. It should also be done in alternating directions, usually at 90 deg angles to each other.

Black lacquer is usually used as a guide coat for sanding. a guide coat is usually "dusted" on, not used as a full coat to sand off. The "dusting" is done lightly to provide a contrast that is visible when sanding. When dusted properly, then block sanded, low spots will show up when started. They are the spots that the "dusting" of the lacquer doesn't come off right away. The idea is to sand until all of the lacquer is sanded off. Theoretically, if blocked properly, once all of the black is gone, the panel has no high or low spots. I usually do it atleast 2 times to make sure that I haven't just moved them.
 
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