Final grits prior to next step cheat sheet

Toolin

Toolin

Promoted Users
Well before I joined, I have been searching final grits before I go on to the next step. Not being a professional or very experienced I would like to work up a cheat sheet because I tend to forget things overtime.

I ask what the coarsest grits would be acceptable for a quality restoration? I know not everyone has the same opinion and some may use finer grits for various reasons such as so they don't inadvertently break through sanding. So please I'd like to hear from as many of you as possible. Here is a draft of my cheat sheet.

Final Sanding Grits​

Bare steel for epoxy P80

Epoxy for filler or poly primer: 7-14 days Scuff or sand 180-320.

Past 14 Days - Scuff or sand 180-320 & recoat with epoxy.
Epoxy for 2K primer: 8 to 14 days Scuff or sand 180-320, 180 preferred.

2K primer for additional coats of 2k: 180, maximum of 24 hours prior to next coat of 2K.

2K primer or poly primer for un-reduced epoxy: 180?

2K primer or poly primer for epoxy as sealer reduced 1:1:1 for solid color Base or Single Stage P320?

Reduced Epoxy as sealer for Base or Single Stage: 8 to 48 hours not sanded before color?
If sanded 400-wet for solid colors, 600-wet for metallics?
 
Last edited:
It has been suggested before I think, but if someone were to scour this forum for all the wisdom posted over the years and pull it together into a book, it would be the best auto body/painting resource ever.
 
Here is the process that I have settled on in the last few years.

Bare metal 80 grit, then epoxy
Filler work 80 grit then finish 120-180 grit (depends in my mood:))
Polyester glaze 120-150 grit (150 works well better than 180
Scuff epoxy with 150 or 180
Re-epoxy then either Polyester primer or 2K urethane
If Polyester primer block with 120 grit. Never go any finer than that.
Re-prime and re-block if necessary, sand with 120 grit. Continue process till straight
Once straight then sand poly with 180 if there is enough material to do so without breaking through,
If not skip to applying epoxy. 2-4 coats less if 180, more if 120
If finished with 180, then 320 dry followed by 600 wet.
If finished with 120 then 220 dry, 400 wet then 600 wet. Sometimes I stop at 400 but if I'm doing a metallic then always 600.
Seal with epoxy 1:1:1 (must have uniform base to do this)
then base/clear or single stage.
 
Dean Jenkins said:
It has been suggested before I think, but if someone were to scour this forum for all the wisdom posted over the years and pull it together into a book, it would be the best auto body/painting resource ever.
Click to expand...
Dean, you are so correct. My purpose was to have a simple to read document I could reference. As you suggest if someone took the time to compile such a book it would be a valuable reference for people such as us.

I have painted a handful of cars in my younger years. All lacquer. Back then things were simple and the standards people worked to are nothing like they are today.
Nowadays the products have changed and are so superior to what they were before. Learning to use them properly and safely at my age it's a significant task. There are so many nuances when researching related topics. Often people tend to leave out things they believe to be common knowledge and inadvertently talk over one's head. The reason I like this site so much is the members here never intentionally do that ever! So many questions I have. Not just sanding grits, substrates do's and don’ts, recoat windows, flash times, numerous product quality issues, mixing ratios, activators, retarders, accelerators, even mixing cup inaccuracies for cripes sake. I can go on and on.
 
Thanks Chris,
This is a response I was hoping for. I expected you would come through.:)

EDIT: Concise and the point. Everything I asked was addressed. And anything I didn't need to know was not.
 
Last edited:
Chris_Hamilton said:
Here is the process that I have settled on in the last few years.

Bare metal 80 grit, then epoxy
Filler work 80 grit then finish 120-180 grit (depends in my mood:))
Polyester glaze 120-150 grit (150 works well better than 180
Scuff epoxy with 150 or 180
Re-epoxy then either Polyester primer or 2K urethane
If Polyester primer block with 120 grit. Never go any finer than that.
Re-prime and re-block if necessary, sand with 120 grit. Continue process till straight
Once straight then sand poly with 180 if there is enough material to do so without breaking through,
If not skip to applying epoxy. 2-4 coats less if 180, more if 120
If finished with 180, then 320 dry followed by 600 wet.
If finished with 120 then 220 dry, 400 wet then 600 wet. Sometimes I stop at 400 but if I'm doing a metallic then always 600.
Seal with epoxy 1:1:1 (must have uniform base to do this)
then base/clear or single stage.
Click to expand...
The only thing I would add to the above is the application of Guide Coat during the final sanding stages. It ensures that you have all the scratches and imperfections removed prior to painting. I like the 3M Dry Guide Coat. It's a fine powder that can be used when dry or wet sanding.
 
I have some black guide coat and use it. I do need some white or a bright color for blocking black epoxy though. I had read somewhere on this site of a talc or chalk like product I believe is some type of art Supply. Does anybody know when I'm speaking of? I forgot what it was called.
 
Chris_Hamilton said:
Here is the process that I have settled on in the last few years.

Bare metal 80 grit, then epoxy
Filler work 80 grit then finish 120-180 grit (depends in my mood:))
Polyester glaze 120-150 grit (150 works well better than 180
Scuff epoxy with 150 or 180
Re-epoxy then either Polyester primer or 2K urethane
If Polyester primer block with 120 grit. Never go any finer than that.
Re-prime and re-block if necessary, sand with 120 grit. Continue process till straight
Once straight then sand poly with 180 if there is enough material to do so without breaking through,
If not skip to applying epoxy. 2-4 coats less if 180, more if 120
If finished with 180, then 320 dry followed by 600 wet.
If finished with 120 then 220 dry, 400 wet then 600 wet. Sometimes I stop at 400 but if I'm doing a metallic then always 600.
Seal with epoxy 1:1:1 (must have uniform base to do this)
then base/clear or single stage.
Click to expand...
Are these grit recommendations for using a DA or by hand? Hand sand is usually more aggressive. So, a 600 by hand could be like a 400 on a DA. Would you agree with that?
 
AAE, I don't have much experience DA finishing, but I would agree with that when it comes to the finer grits. Even in Collision Repair I've always finished by hand for the most part.
 
There is no bad advice here, but I will throw in my process for what it is worth. Everything identical as Chris with exception of when primer is straight in your 1xx grit, I spray 2 coats of 2k, guide coat and dry sand 320 on a da with an interface pad, seal and paint if it is ANYTHING but a first top tier job. I have found the tendency with 4 or 600 by hand is that unless you’re doing it every day and have the feel for it doesn’t get sanded enough. Just “feels“ smooth instead of cut flat.
 
Toolin said:
I have some black guide coat and use it. I do need some white or a bright color for blocking black epoxy though. I had read somewhere on this site of a talc or chalk like product I believe is some type of art Supply. Does anybody know when I'm speaking of? I forgot what it was called.
Click to expand...
SPI black epoxy primer dries shiny. So when you start sanding it turns dull and in a sense is it's own guide coat.
Shiny spots are the low spots, when it's all dull looking you are ready for the next step.
 
'68 Coronet R/T said:
SPI black epoxy primer dries shiny. So when you start sanding it turns dull and in a sense is it's own guide coat.
Shiny spots are the low spots, when it's all dull looking you are ready for the next step.
Click to expand...
Slick Sand is the same, not black of course, but a noticeable color difference between sanded and unsanded, works like a guide coat. I use black epoxy under it so highs are obvious as well.
 
I found the thread, actually there's a number of them where Shine mentions using Pounce Powder. A lot of guys must be using it cuz I found it at TCP Global. Comes in White, Black and Blue, $5 for 16 Oz.

http://www.spiuserforum.com/index.php?threads/guide-coats.4069/

Shine said:
"i see thread after thread about guide coats around the web. first off i hate anything 3m , just a burr under my saddle. plus it's high . i dont like spray bombs because the crap gums up and also cost too much.
since around 1974 i have used black pounce powder or white powder. i used it to transfer flames with a pattern . accidentally spilled some on a bike tank and smeared it around trying to wipe it off the primer. lights went on ! this was years before 3m came out with their little tub for 10 times the cost.
for the 30 dollars you pay for 3m you can get 16oz of black/white pounce powder and a nifty little applicator . this is going to last you forever."
 
'68 Coronet R/T said:
SPI black epoxy primer dries shiny. So when you start sanding it turns dull and in a sense is it's own guide coat.
Shiny spots are the low spots, when it's all dull looking you are ready for the next step.
Click to expand...
I think using a white or blue guide coat would be beneficial on black epoxy when moving up in grits to make sure you have completely blocked out all the bigger scratches.
 
You must log in or register to reply here.
Back
Top