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Final sanding grit before primer?

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PostPosted: Tue Apr 19, 2011 10:29 am
I had read the sticky up top, and have been reading just about every post on this forum. Origionally I thought 220 grit sanding would be sufficient before I applied my 2k primer. Now im reading alot of people are reccomending going to 320 grit then using a red scuff pad?

what is the ideal way to prep a previously painted surface for primer then bc/cc

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PostPosted: Tue Apr 19, 2011 1:00 pm
180 220 320 ALL are aggressive enough to key your primer.i use 320 on new body panels because i only need 2 coats of primer ,or 320 ideal for wet on wet.
fail to prepare ,prepare to fail.

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PostPosted: Tue Apr 19, 2011 1:25 pm
Here's what I do

I finish filler with 240's,DA the immediate area with 240's and then red scotch the paint in the surrounding area .... that works for me :goodjob:



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PostPosted: Tue Apr 19, 2011 1:39 pm
Most of my panels are already 220'd. If i just use a red scotch pad after the 220 will I be ok? Im just worried my 220 scratches will show through in the end.

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PostPosted: Tue Apr 19, 2011 3:50 pm
I have been spraying 2K primer over 80 grit scratches (In bondo) for years with no problems at all......................................
I do feather the surrounding area with 360-400.
"The number of parasites in the USA has now eclipsed the number of productive members of society"


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PostPosted: Wed Apr 20, 2011 7:00 am
sounds like ill be fune with my 220 then haha

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PostPosted: Wed Apr 20, 2011 12:41 pm
ITS BEST finishing of your bondo ,before priming with 180. less the depth of scratch ,less primer is needed. deeper the scratch more shrinkage you will get later down the road.People load up primer to fill in 80 scratches.LESS IS BEST.
fail to prepare ,prepare to fail.

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PostPosted: Thu Apr 21, 2011 2:15 pm
Any time I've ever primed 80 (with various different primers) its resulted in sinking, usually right after the bake cycle or about a week air-drying. 120 seems to be the most common finishing grit among the shops I've been to but most manufacturers I've come across suggest at least 180.
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PostPosted: Thu Apr 21, 2011 2:17 pm
:goodpost: JIMMO
fail to prepare ,prepare to fail.

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PostPosted: Thu Apr 21, 2011 5:34 pm
Wow,,,I must be doing something different.

Remember, Im not leaving any 80 grit scratches in the surrounding painted area, just the bondo. (Thats where you get a problem from, not from the bondo)
Do you wipe the surrounding area with W&G remover before you spray the primer?

How soon do you block and sand it after you spray it? After a week of air dry, you would not have any shrinkage. What kind of primer do you use?
"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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