what grit sand paper for 2k primer

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PostPosted: Wed May 15, 2013 12:10 am
hi just wanting to know what grit for sanding 2k primer for acrylic lacquer top coat
400 or 600 w/d . also will a maroon scotch brite be enough for scuffing the door jambs and hard to get to places , can you sand it a couple of days before applying the top coat some one told me that the it could heal itself

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PostPosted: Wed May 15, 2013 6:20 am
400 will work but 600 is much safer, especially for metallics.
Most wet sand with 400 for non metallics.
I would use a gray Scotchbrite pad, the red is to coarse to paint over.
good luck.
JC.

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



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PostPosted: Wed May 15, 2013 7:35 am
yeah thanks mate,,
it is a solid colour i am useing so i guess either 400 or 600 will do the job
i have some grey scotch brite pads so i will use them



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PostPosted: Wed May 15, 2013 10:20 pm
your using a two part primer 2K and then a lacquer over the top
you will want to sand the primer with 500 to 600 grit wet .
the jams i would also sand wet with a gray pad and a product like sem's scuff & clean . red pads have the sanding grit of about 220 paper so it's a bit much for lacquer top coats if your not using a sealer 1st .
you could do the gray pad sanding dry but it will take a lot of work to take the shin off .
if your not going to spray your top coat on with in a 12 hour time frame you will want to seal the panels 1st or go over every thing with a gray pad to open up the sand scratches again or the top coats will not stick .
you would be better off to use a wet on wet sealer if you can't spray with in the 12 hour window after prepping the panels .

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PostPosted: Thu May 16, 2013 7:14 am
DK said,,"if your not going to spray your top coat on with in a 12 hour time frame you will want to seal the panels 1st or go over every thing with a gray pad to open up the sand scratches again or the top coats will not stick"

Where did you get this information from???? Its not true.

Also the maroon (Red) 3M scotch brite pad is any where from 360-400 grit, not 220.

http://academic.evergreen.edu/projects/ ... finish.pdf

Please check your information before posting it on the forum..........
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PostPosted: Thu May 16, 2013 7:48 am
as a long time BASF rep , a long time dept head of coating it porsche AG and now the owner of 3 shops , high end car only , race shop and airbrush shop i got it right from the makers of the products !

sanding pads do not work the same ways as sanding papers do they do not say at the same grit thru out the using life of the pad .
red pads will start out as again (about) a 220 grit as you use it will brake down to a using grit of 400 before the pad is dead and past it's usible life .
the info is not wrong it's how sanding pads work .
now because sanding pads are not rated as a P cutting grit like sand papers the fact is you really can not get a sanding pad that is classed in the same sanding cut grits as sanding papers .
you will see posting of what pads are equal to under sanding papers well you can't truly cross one over to the other that is why you do not see a grit rating on the other than say mediun , fine ,extra fine and so on one like i stated they change there grit as they are being used and two no two makes of sanding pads cover the cut grits they are all about or with in a rang of grits . that is what the word ABOUT is used for .
Last edited by dkbautosports on Thu May 16, 2013 8:32 am, edited 1 time in total.



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PostPosted: Thu May 16, 2013 7:59 am
yeah now i am a bit confused i would of thought that after you sand the primer it would stay sanded or scuffed
for how ever long,, if the primer has had a week or so to set off



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PostPosted: Thu May 16, 2013 8:51 am
no it does not the sand scratches will start to close up .
you will have to brake open the sanding scratches again to get the unsercoats and top coats to stick or use a sealer . i will add even using a sealer if the primes sits to long from the time it was sanded to the time you seal it to will also not bite in and stick .
you do have some time different products will have different windows of the amount of time but to be safe it's 12 hours for most products .
the same does hold true for things like base coats there is a window were you should get clears on top .
when it comes to sanded primers the more solids there are to it the less of a window you will have .
you will see this with many high build primes were it's ez to sand with in 6 or so hours after you apply the primer but you wait 24 plus hours and it's like sand concrete this is because the polamers along with kaolin ,butyl acstate, zinc phosphate have linked closed and locked together . now by sanding you will reopen the links but they want to naturally close back on them selfs and will do so again over time just sitting .

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PostPosted: Thu May 16, 2013 9:08 am
BASF,, I understand now.
Garth, dont believe everything he says. Its not true.
A red scotch brite pad starts out as 400, and ends at 400. Most good painters know that....
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PostPosted: Thu May 16, 2013 11:48 am
SCOTCHBRITE GRIT CHART
3M Scotch Brite Nylon Pads:
7445 - White pad, called Light Duty Cleansing - (1000) 1200-1500 grit
7448 - Light Grey, called Ultra Fine Hand - (600-800) 800 grit.
6448 - Green (?), called Light Duty Hand Pad - (600) 600 grit
7447 - Maroon pad, called General Purpose Hand - (320-400) 320 grit
6444 - Brown pad, called Extra Duty Hand - (280-320) 240 grit
7446 - Dark Grey pad, called Blending Pad (180-220) 150 grit
7440 - Tan pad, called Heavy Duty Hand Pad - (120-150) 60(?)
Blue Scotch-Brite is considered to be about 1000 grit.
(The value inside the parentheses is directly from 3M.)
3M Chart
JC.

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