Filler Over Old Epoxy

Machspeed

Machspeed

Member
Hey gang, dying to use Deans sanding blocks that I bought over a year ago, I put some 180 on them and went to block sanding the roof of my car today to expose flaws. I had banged out most of the dents but knew I had some areas that would require a very thin coat of filler. The epoxy I sanded is probably four years old, as I media blasted the car all those years ago then put two good coats of SPI epoxy on it. In the photo, you can see (See photo) some of the low spots that need to be addressed. Can I put filler in those exposed low areas without spraying a fresh coat of epoxy?
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By the way, while I'm total rookie and have limited experience with sanding blocks, I can say that Deans Black Diamond blocks are far better than the old Dura-Blocks. The weight of them and the ability to match the contours of the car make for easy sanding. Love'em!

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I agree 100% with crashtechs advice. At some point your going to have to sand all of the epoxy before recoating but, using your roof as an example, you should sand those low areas to be filled....... spray, brush or roll fresh epoxy over those areas to be filled, next day or two fill the low spots, sand and epoxy those areas. If you want to spray the entire roof again, go ahead. It's not going to hurt anything other than saving a bit of epoxy material.

Once you get to the point your comfortable with all your filler work on the car, sand the entire car with 180 grit, spray two more coats of fresh epoxy and move on to your next stage, 2k urethane or polyester primer.

Hope that made sense.
 
Acrylic blocks are not in the same class as hard foam or rubber blocks. It’s like comparing a Corvette to a Prius.

You need to give it another coat of epoxy. Wait a day, give it a light block with 180-220 only to find your low spots then go to your filler.

Sanding the next day isn’t necessary for filler but I like it just to show where the low areas are.
 
I always hand sand any low spots with 180 git to make sure there is good adhesion with new primer. A low spot isn't a place to have to worry about loss of adhesion.
 
Looks like the consensus is recoat, which is what I thought. I've exposed all the lows and it would sure be easier to apply that filler now to the obvious areas. Prior to sanding, those areas were not so obvious. Think I'm going take MJM's advise and spray the lows, then filler. Car will receive full sanding and re-epoxied. Thanks gentlemen!
 
Machspeed said:
Looks like the consensus is recoat, which is what I thought. I've exposed all the lows and it would sure be easier to apply that filler now to the obvious areas. Prior to sanding, those areas were not so obvious. Think I'm going take MJM's advise and spray the lows, then filler. Car will receive full sanding and re-epoxied. Thanks gentlemen!
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I would definitely spray the entire roof, not just the low spots. You don’t how to worry about filler being spread out past where fresh primer is, you can still fill other areas you might have missed the first time, more epoxy on your roof is only a good thing, it doesn’t take any more time to mix or spray, you’ll need to sand and clean the entire roof anyways so it’s already going to be prepped, and the cost savings is marginal.

There’s not a single good reason to only spray the low spots. Every pro here would respray the entire roof.
 
Here's a video showing a spot repair. He's using 2k primer but, you can substitute the 2k for epoxy in your application.

I'm sharing this with you so you can expand your knowledge and skills. From this video you'll learn how to mask so you don't leave a hard edge. Also how to feather paint using the gun trigger. I recently learned this last year. It's very helpful, almost mandatory for spot repairs.

Like I mentioned earlier, absolutely nothing wrong with re-priming the entire panel for a spot repair, other than material usage. It's been stated 8oz per panel sprayed. Two coats would be 16oz. That's a fair amount of material usage, imho.

As an example, another benefit to a spot repair in the primer stage is......you found a low spot after sanding that requires filler. So you spot spray more epoxy, wait a day or two, then spread filler, sand, and spot spray epoxy. You check your work once again by sanding the spot repair to see it's still a bit low. So you fill it with glazing putty and spot prime again. Spot priming that area saved you around 32 oz of primer not spraying an entire panel four times........ And you learned a masking technic along with a gun control technic.

Enjoy the experience, I have :)

 
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MJM said:
Here's a video showing a spot repair. He's using 2k primer but, you can substitute the 2k for epoxy in your application.

I'm sharing this with you so you can expand your knowledge and skills. From this video you'll learn how to mask so you don't leave a hard edge. Also how to feather paint using the gun trigger. I recently learned this last year. It's very helpful, almost mandatory for spot repairs.

Like I mentioned earlier, absolutely nothing wrong with re-priming the entire panel for a spot repair, other than material usage. It's been stated 8oz per panel sprayed. Two coats would be 16oz. That's a far amount of material usage, imho.

As an example, another benefit to a spot repair in the primer stage is......you found a low spot after sanding that requires filler. So you spot spray more epoxy, wait a day or two, then spread filler, sand, and spot spray epoxy. You check your work once again by sanding the spot repair to see it's still a bit low. So you fill it with glazing putty and spot prime again. Spot priming that area saved you around 32 oz of primer not spraying an entire panel four times........ And you learned a masking technic along with a gun control technic.

Enjoy the experience, I have :)

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Why are you doing all of that spot spraying? None of that is necessary. Spray the entire panel once to get a fresh coat, do your filler work, use guide coat to tell you where low spots are. You don’t need to spray any epoxy again until you’re done with all the filler work and want to cover bare metal sand thru spots prior to high build.

In that case I will spot spray bare metal spots, allow proper flash, then spray the entire panel once more. This gives sand thru spots 2 coats and adds more mil to the rest of the panel that’s probably had a coat sanded off by this point.
 
Lizer, check your PM's. I sent you a link to some breathing exercises.

Very useful information to relieve stress that happens in day to day life.

Happy Holidays.
All the best to you and yours.
 
MJM said:
Lizer, check your PM's. I sent you a link to some breathing exercises.

Very useful information to relieve stress that happens in day to day life.

Happy Holidays.
All the best to you and yours.
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Says the guys who “quit” the forum and would no longer use SPI product in a tantrum.
 
Would you like me to leave the forum and stop using SPI products?

Please tell me what I can do for you so you'll have a happy and joyous Holiday?

All the best to you and yours,
 
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I'm more interested in why you think it's necessary to spot spray every time to check for low spots instead of simply using guide coat.
 
Hey friends, I'm truly grateful for all the input I receive here. As a newbie, I have quickly learned in this field that there are many ways to approach a problem and achieve the same results. In that, I look for advice and take the route that bests suits my needs. I believe both of the above suggested routes would get me what I want and I thank both of you for commenting. However, I never want to be one whom starts a thread that moves into some unrest. We can always agree to disagree and be civil about it. Thanks fellas, appreciate you!
 
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