# Painting my frame. Should I sand the primer?



## f3rg (Aug 29, 2007)

I see a lot of conflicting opinions of this, so I thought I'd ask you guys. The frame is steel, and it's already been primed, but the primer is rough.

Should it be sanded before painting, and if so, with what grit?

Thanks.


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## Godfather1138 (Aug 13, 2011)

Depends on the finish you want to end up with. Most painters will block out or wet sand the primer to a nice smooth surface with increasing # sand paper (higher # = finer grit). Most guys will stop somewhere around 800 b/c you still want to give the paint something to adhere to. This is if you are wanting the slickest finish possible. If you are just wanting a matte finish where smoothness isn't totally important you can just scuff and go.


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## cbchess (Dec 20, 2003)

yes!
minimum 220


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## f3rg (Aug 29, 2007)

Thanks, guys. I already hit it with 400 grit, and I'll do 800 next. Its previous finish was matte and I couldn't stand it, so I want a very smooth finish this time around.


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## Godfather1138 (Aug 13, 2011)

cbchess said:


> yes!
> minimum 220


Which would be the scuff and go method 

A tip to speed up a 220 - 320 grit wet sand prior to paint is to use a green scotchbrite pad. They clear the residue easily and will last longer than sandpaper (even paper intended for wet sanding). They are not exactly a specific grit, but fall around that range and do a great job of getting your surface prepped and ready for paint.


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## flynfrog (Feb 4, 2011)

I wouldn't go much past 600 you will start to lose to much bite on your paint. Check with the data sheet for the paint you are using most are 400-600. The color will make a difference to metallics will settle into any sanding scratch you missed.


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## Yogii (Jun 5, 2008)

Don't sand so much that you remove the primer. Corners and edges are the most vulnerable...


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## doug fattic (Mar 11, 2010)

flynfrog said:


> I wouldn't go much past 600 you will start to lose to much bite on your paint. Check with the data sheet for the paint you are using most are 400-600. The color will make a difference to metallics will settle into any sanding scratch you missed.


My understanding of what grit to use on primer is the same as flynfrog's. 600 grit is the finest I use.


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## jgerhardt (Aug 31, 2009)

Many automotive shops only go up 320 grit wet sanded.


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## dbohemian (Mar 25, 2007)

Doug (also flyinfrog) are of course correct. Doug has been a professional painter for 30+ years? Or something like that amount  (Hi Doug)

Automotive shops may only go to 320 because of speed. Time is money of course. That is not necessarily what does the best job. If using metallics or pearls you must sand to a finer grit (600 wet is standard) to reduce sand scratches that can be seen after clearing.

I use dry papers that are graded to a particular coursness. Realize that 600 wet would typically be something like 800 dry and that a lot of papers are now micron graded so there is not an absolute direct correlation. 

Good luck, lets see pictures after you are done.


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## deepat (Sep 9, 2011)

flynfrog said:


> I wouldn't go much past 600 you will start to lose to much bite on your paint. Check with the data sheet for the paint you are using most are 400-600. The color will make a difference to metallics will settle into any sanding scratch you missed.


I agree...


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## Cheakas (Feb 2, 2006)

I usually do only minimal sanding on primer, pretty much just knocking down any rough spots. Then I use the first base coats as guide coats and sand them flat. That way there's less of a chance of sanding though the primer and having to respray primer. It's a lot more time consuming and uses more paint, but I think the results are worth it.


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