Body and Paint Questions

[Detroit Iron]

I want to start a thread where us beginners can post questions for the pros and experienced body and paint guys. I have so many questions, it seems silly to create a thread for each question as it comes up.

My first question: After blocking and feeling satisfied with my body work; do I need to spray a final application of primer before I paint? Or, can I paint over the body work as shown?

 

[Detroit Iron]

I've seen sand papers with a P in the grit level. What's the P stand for? Premium? I'm guessing that these P grade papers are used for final sanding?

 

[Detroit Iron]

Scotch-Brite, or "sanding sponges". After a final sanding of 400, 500, or 600 grit, does anyone recommend a final wipe down with Scotch-Brite pads? When would they be used if ever? What are your thoughts on Scotch-Brite pads?

 

[bearman]

I want to start a thread where us beginners can post questions for the pros and experienced body and paint guys. I have so many questions, it seems silly to create a thread for each question as it comes up.

My first question: After blocking and feeling satisfied with my body work; do I need to spray a final application of primer before I paint? Or, can I paint over the body work as shown?

View attachment 962928

I always recover any non primed areas. Then block down

 

[bearman]

I've seen sand papers with a P in the grit level. What's the P stand for? Premium? I'm guessing that these P grade papers are used for final sanding?

View attachment 962929

P is for premium for sure.

 

[bearman]

Scotch-Brite, or "sanding sponges". After a final sanding of 400, 500, or 600 grit, does anyone recommend a final wipe down with Scotch-Brite pads? When would they be used if ever? What are your thoughts on Scotch-Brite pads?

View attachment 962930

I don't use them on the body or bodywork. I'm interested to know how this product is used

 

[snakeoil24]

I want to start a thread where us beginners can post questions for the pros and experienced body and paint guys. I have so many questions, it seems silly to create a thread for each question as it comes up.

My first question: After blocking and feeling satisfied with my body work; do I need to spray a final application of primer before I paint? Or, can I paint over the body work as shown?

View attachment 962928

A good priming will have multiple blocking, repriming possibly 4 times.

 

[69L48Z27]

I want to start a thread where us beginners can post questions for the pros and experienced body and paint guys. I have so many questions, it seems silly to create a thread for each question as it comes up.

My first question: After blocking and feeling satisfied with my body work; do I need to spray a final application of primer before I paint? Or, can I paint over the body work as shown?

View attachment 962928

You’ll want to use a primer surface over that type of body work. Block again. Once your done with all that you’ll use a sealer before final paint layer.

Scotch-Brite, or "sanding sponges". After a final sanding of 400, 500, or 600 grit, does anyone recommend a final wipe down with Scotch-Brite pads? When would they be used if ever? What are your thoughts on Scotch-Brite pads?

View attachment 962930

Scotch brite pads are used to scuff an area or primer to get it opened up to coat again with primer or sealer. I would not use them after sanding.

What do you mean ‘wipe down’?

 

[snakeoil24]

Scotch-Brite, or "sanding sponges". After a final sanding of 400, 500, or 600 grit, does anyone recommend a final wipe down with Scotch-Brite pads? When would they be used if ever? What are your thoughts on Scotch-Brite pads?

View attachment 962930

Sand paper scotch brites are ex-pensive and irregular

 

[Frank Mopar]

The “P” has something to do with the system used to grade it. It does not mean premium.

 

[bearman]

The “P” has something to do with the system used to grade it. It does not mean premium.

Frank the 3m guy told me that the p was for premium. Now maybe he doesn't know what he was talking about. Salesman will call it anything you want it to be called as long as it's sold. Thanks will dig deeper into what it really stands fore.

 

[CHARGERSTEVEN]

The “P” has something to do with the system used to grade it. It does not mean premium.

You are 100% rite,its a system to grade the grit they use

 

[69L48Z27]

Here’s all you’ll ever need to know about sand paper.

P means it meets a certain standard, not sure that makes it premium.

‘If the grit number is preceded by the letter "P", such as P2000, this indicates FEPA grit. Most sandpaper today is manufactured according to the international FEPA standard.’

https://www.onlineindustrialsupply.com/frasqu.html

 

[Builderguy]

If the grit number is preceded by the letter "P", such as P2000, this indicates FEPA grit. Most sandpaper today is manufactured according to the international FEPA standard. Grit size refers to the size of the particles of abrading materials embedded in the sandpaper. A number of different standards have been established for grit size.

 

[Builderguy]

Sorry, didn't see you already posted this.

 

[Builderguy]

Detroit Iron,
Just like 69L48Z27 said, "You’ll want to use a primer surface over that type of body work. Block again. Once your done with all that you’ll use a sealer before final paint layer."
I would only add that if you are new to this, spray some guide coat on your panel and then lightly block (before your seal coat). The surface can feel smooth but still have highs and lows that will show when painted. It is very cheep insurance that this doesn't happen. Then you can seal coat it.

 

[1 Wild R/T]

Few points... What are you using as a sanding block? How big? Are you using guide coat?

If you paint over what you have shown above you'll see the sharp color contrast through most paints.... At least shoot a sealer.... Personally I'd re-prime, guide coat & cut it again... I've never heard someone say "I blocked that panel to much".... I've heard lots of folks say "I should have blocked that panel again".....

I like Dura-Block sanding blocks, I prefer at least a 12" block, if the panel is mostly flat or a convex curve I like using an 18" or bigger block... The longer the block the flatter/straighter you'll get the panel.... I have a 30" block for doing roofs....

Guide coat is typically misting black spray paint over the fresh primer, that way when you sand the high spots immediately become apparent cause you cut the guide coat off as soon as you start sanding.... The low spots keep their black speckles till you've cut the high areas away around the low spot....

Depending on how bad the highs & lows are you might want to break out your body hammer... Pecking down high spots & pecking up low spots...

Also if you have a low spot & you plan to re-prime a little extra heavy on the priming in known low spots can help straighten a panel...

Just a little to think about...

 

[1 Wild R/T]

Guide coat..

I prefer to start with more aggressive paper, nothing finer than 80 grit, sometimes as aggressive as 36 grit.... Reason for that you let the paper do the work, Just lightly sand the panel and let the paper do it's job.... If you start with 120-150 or even 180 they remove material so slowly you'll wind up pushing rather then letting the paper do the work, so you won't get a flat cut, the metal will flex, the sanding block will flex...

Once the panel is truly flat the next grade of paper is just removing the scratches caused by the more aggressive paper & maintaining the shape you created in the earlier steps...

 

[vintage chromoly]

Good sanding blocks are very important. I have a large collection of blocks. I have every block that durablock makes and I only use a couple of them anymore. I’ve found that, for getting panels really flat, a Hutchins block is far superior. They don’t flex and cannot be pushed into the “lows” like a durablock can.

 

[vintage chromoly]

Also, check out SPI for primers and clear.
Great product and a great value!
Top notch customer service, and they have a user forum that cannot be beat.