I have been wet sanding with 400 grit paper and have it looking good(when wet), but I have a few waves in the deck lid> I have searched looking for tips on this and ran across one that had been sanding in S & X patterns. I was told to sand in straight lines and not to cross. Is that a correct way to get panels straight?? Any other thoughts are much appreciated!!!! THANKS Randy

Randy you NEED to sand in a X pattern. If you sand in just straight lines you will never get the panel straight. The reason is because if you sand just in a straight line your block can ride over the high and lows and not "cut" them down. But if you sand in the X pattern the block doesnt ride over the high and lows, it levels them out.

This isnt the best description why to sand in the X pattern but you do NEED to sand in that method in order to get a straight panel. Also that 400 grit paper might be a little rarsh you might want to think of switching to 500 or even 600 grit. 400 girt stracthes could be alittle to much for your paint to fill meaning you will get sand stracthes showing through the paint. The shop I work at went to 400 to 500 for that reason...Eric


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1970 chevelle
1970 chevelle SS455 not a typo its a buick baby
1949 and 1972 chevy trucks
http://briefcase.yahoo.com/bc/sevt_chevelles

Eric, thanks for the help. I will start going back over things with a different grit and a new pattern. Thanks Randy

Originally posted by sevt_chevelle:
Randy you NEED to sand in a X pattern. If you sand in just straight lines you will never get the panel straight. The reason is because if you sand just in a straight line your block can ride over the high and lows and not "cut" them down. But if you sand in the X pattern the block doesnt ride over the high and lows, it levels them out.

This isnt the best description why to sand in the X pattern but you do NEED to sand in that method in order to get a straight panel. Also that 400 grit paper might be a little rarsh you might want to think of switching to 500 or even 600 grit. 400 girt stracthes could be alittle to much for your paint to fill meaning you will get sand stracthes showing through the paint. The shop I work at went to 400 to 500 for that reason...Eric


Eric is correct. In 1958 (Don't say it! "Old Guy?"), I had to wet sand between every coat of Black Laquer on my '41 Buick Coupe. Nine (9) coats total. The guy (Shop owner) would call me up every other week and say "Richard, it's time to sand the next layer").

Sold the Buick a year later, and saw it five (5) years later.

IT WAS STILL "PERPECT!!!!!"

Anyway, on our '69, we sanded on a 45 degree angle in one direction, then a 45 degree angle in the opposite direction.

That basically equals an "X" pattern.

TEAM MEMBERS, "Chime In!"

Hope this helps a little.




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Team Members Forever #341

Richard, Judy, MAXX2

'69 Elke (Frame Off); GM HO 350/330-Mildly Ported Vortec Heads-Manley Severe Duty SS 2.02/1.60 Valves, Comp Cams Full Roller Package (Magnum)-Custom Grind CS 3315/3316 HR112-.510/.520 Lift, Edelbrock Air-Gap W/750 Performer Manual Choke-Performer 100 HP NOS, March Pulleys, 4L60 (Non Computer) W/Lokar Shifter, 12 Bolt Posi.

Agree on crosshatch sanding. Have slightly different opinion on grits to use. The coarser grit papers cut straighter. We use 80 grit for filler, after a top cut with 40 grit. Glaze coat (poly) is blocked with 150 or 180, most feathering is done with 180, sometimes with 240 grit. The panel should be straight before applying a primer surfacer. Then can block with 320 or 400 grit. Agree with Eric however, that on some colors, (very high metallic), the matallic base can orientate itself in line with 400 scratches, even when sealer is used. Final sand can be done with 600 grit if you want ot reprime and reblock, but the panel should already be straight. NOTE: all of our paint and undercoat products are catalyzed materials. Karl

Karl I agree with you on the grits. All my blocking of primer is done with 220, just cuts faster and like you say straighter. Then I prime it once more and then go to the 500 or 600 then apply the base clear.

I would go with 220 rb, and once you are happy with it, prime it once more then use the 500 grit. No need to use sealer if the whole car is painted with 2K primer...Eric

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1970 chevelle
1970 chevelle SS455 not a typo its a buick baby
1949 and 1972 chevy trucks
http://briefcase.yahoo.com/bc/sevt_chevelles

If you are seeing 'waves', 400 will never level them.
You either have:
High spots, which would need to be cut down (sanded)
Or, low spots, which need to be filled.

Or, both high and low spots.

I would start by coating the area with a good layer of primer/filler.

Take a board sander with 180 and do the cross-hatch pattern sanding. repeat as nessecary until the low spots are filled. If you keep seeing high spots appear, they may need to be tapped down with a body hammer & dolly.

When you believe the panel to be flat, THEN get out the 400 and wet sand. Use a rubber squeegeee to remove the water often and look at the panel from an eye-ball level to check for more waves.

just a thought to add to Jimmy's advice. Don't forget to dust on a guid coat of contrasting primer. X with 180 till it all comes off evenly. Then reprime and wet sand with 400.
I like to mist the area after sanding and
pull the overhead light through the reflection b-4 I squeegeee it off .
you then have both the reflective read and the squeegeed off sanded surface to verify your panels flatness/conformity



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Wayne
ACES# 1556
TCG # 186

THANKS TO ALL WHO POSTED!! I will reprime and start to wet sand . I had some areas that are flat as far as body work goes,but I think my blocking has produced some waves from the straight pattern that I was using.. Thanks Again Randy

Definitely use a guide coat (cheap spray can paint in a contrasting color) applied sparingly. Use the longest sanding block you can, it really helps flatten the surface and avoids digging in.