Epoxy recoat and sanding

5

50Shep

Promoted Users
Hi, I know the tech manual says that after 7 days epoxy should be re-sanded with 180 grit. Reading through this forum I've seen some variances here in grits. Is this a function of time?

Like at 7 days you are probably safe to scuff with a gray pad and then coat with reduced or unreduced epoxy.
At one month you should use 320 grit.
At 3 months you should use 180...

I'm guessing here on the grits. I've just seen a lot of people on here saying after seven days they "scuff" even though the manual says 180 grit. Is 180 just the safest bet and to keep people from just scuffing 2 year old epoxy and thinking they are ok?

I have very little time to work on my truck so I keep missing my 7 day window and hitting a running board with 180 grit just seems like starting over. I'm using single stage paint by the way. So far the only primer I'm using is SPI epoxy. Thank you
 
The longer the epoxy sits, (after the 7 days), the more the chemical adhesion starts to go away. Then you are relying on mechanical adhesion. That said, the epoxy seems to stick to itself very well, but it is just as easy to hit it with 180 as 320. Sanding with 180 lightly then a maroon scotchbrite pad works great.
 
Thank you. When you say “do as Texas advised”, are you talking about the maroon scotch pad?

It’s sounds like it is best to stop at 180 until ready to paint, right? So if I epoxy unreduced and get everything straight with 180, there’s really no rush. I stop there. When ready to paint I do 320 dry, 600 wet and seal. Any minor cut throughs will be covered by the sealer? Thanks again
 
50Shep said:
Thank you. When you say “do as Texas advised”, are you talking about the maroon scotch pad?

It’s sounds like it is best to stop at 180 until ready to paint, right? So if I epoxy unreduced and get everything straight with 180, there’s really no rush. I stop there. When ready to paint I do 320 dry, 600 wet and seal. Any minor cut throughs will be covered by the sealer? Thanks again
Click to expand...

What he said here in the context of preparing to do a final application of epoxy.

texasking said:
Sanding with 180 lightly then a maroon scotchbrite pad
Click to expand...
 
approx 1 year ago, I had the body of my MGA sandblasted and primed by a local blaster. The blast shop applied SPI epoxy primer to to the bare metal at that time. Following that, I did more welding on weak spots that were exposed by sandblasting. This is a diy project, meaning every aspect of the job takes longer than expected, so it's been about a year since primer was first applied. So now metalwork is done and I'm getting to the bodywork phase. I understand the need to scuff with 180 grit then maroon scotchbrite. My question is whether there is a subsequent primer recommended between this aged epoxy and the filler layers and or the base coat. As I do not have a paint booth in my shop, I'm curious about using any of the rattle can primers? Any recommendations? Theoretically, I could tent off a small area and use a gun to spray a small portion of the body at a time. But which primer/base is best over the scuffed, aged epoxy? Thanks
 
I am assuming you have some bare metal exposed that you are concerned with. The best approach at this point, in my opinion, is to scuff the entire car with 180 grit and then clean it with Wax and Grease remover (there is a proper technique to this part) and let dry. Mix your epoxy 1:1 and spray the entire car with two coats, waiting the required flash time and keeping metal temps about 70 degrees for the next 24 hours.

The next day you can lightly block sand the panels with 150 grit. This will reveal the low spots and then you can apply your filler and block sand as necessary.

Once body work is done, scuff everything with 180, clean and shoot another coat of epoxy. This will seal the filler and any bare spots and is far and away the best foundation for your paint job.

At that point you should be ready for 2k build primer.
 
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mga1600 said:
approx 1 year ago, I had the body of my MGA sandblasted and primed by a local blaster. The blast shop applied SPI epoxy primer to to the bare metal at that time. Following that, I did more welding on weak spots that were exposed by sandblasting. This is a diy project, meaning every aspect of the job takes longer than expected, so it's been about a year since primer was first applied. So now metalwork is done and I'm getting to the bodywork phase. I understand the need to scuff with 180 grit then maroon scotchbrite. My question is whether there is a subsequent primer recommended between this aged epoxy and the filler layers and or the base coat. As I do not have a paint booth in my shop, I'm curious about using any of the rattle can primers? Any recommendations? Theoretically, I could tent off a small area and use a gun to spray a small portion of the body at a time. But which primer/base is best over the scuffed, aged epoxy? Thanks
Click to expand...
Hi mga1600,

Check out this thread from back in 2010 where Barry lays down some rules and sage advice regarding automotive painting. One of the rules is to "Never look at an aerosol primer can" ;)

What every new painter must read!

As some of you know I get 30-100+ calls a day for tech help and a lot of these calls are from shops that don’t even use SPI and usually the rep from the paint company has just left and expounded his brilliance that you may have done something wrong. “You think?” My idea here is some of the...
www.spiuserforum.com

Like 68 said, use SPI epoxy as your foundation after you properly prep the existing layer of epoxy. You can find the detailed instructions on all the SPI products on this site, and in the forums you can see how they are used by the members, and abused by some of us that are learning and make mistakes. Its a great site, with knowledgeable members who really make a difference with the time they invest helping others.
 
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