High build question

Duke78 · #1 (**permalink**) 10-28-2009, 07:16 AM

I am currently wet sanding my high build primer and i think i screwed up, i appearantly didn't put on the usual 2-3 wet coats on my driver door. I have sanded through the high build down to the Epoxy in several spots. How can i repair this?

I would think that sinice the high build and epoxy is now scuffed with 400 that i should be able to re-apply high build and block it off again. The only other thing i can think of is scuff it up with ~120 and re-epoxy then high build the block off, i really hope not though. Any advice will be appreciated thanks.

Sand_Man · #2 (**permalink**) 10-28-2009, 07:00 PM

In my opinion, you don't need to do anything. The epoxy is there to protect the sheetmetal from rust, right? The high-build primer is there to give you something to block-sand to level the surface. So if you accidently expose some epoxy, you won't hurt a thing. Now if you were to sand to bare metal, then you'd need to lay down a bit more epoxy, since most high-build primers are NOT water proof. I think you'll be fine as long as you (A) don't have any bare steel, and (B) make very sure you use a sealer prior to final paint.

Action4478 · #3 (**permalink**) 10-28-2009, 07:35 PM

Quote:

Originally Posted by Duke78

I am currently wet sanding my high build primer and i think i screwed up, i appearantly didn't put on the usual 2-3 wet coats on my driver door. I have sanded through the high build down to the Epoxy in several spots. How can i repair this?

I would think that sinice the high build and epoxy is now scuffed with 400 that i should be able to re-apply high build and block it off again. The only other thing i can think of is scuff it up with ~120 and re-epoxy then high build the block off, i really hope not though. Any advice will be appreciated thanks.

It sounds as though the body work is not straight yet . needs more surfacer ..(primer )...

e-tek · #4 (**permalink**) 10-28-2009, 11:58 PM

Sand_man is THE man in his answer. I would just add though that really small spots sanded through to the metal are OK (less than 2inches dia) to cover with 2K. Anything bigger,I'd just use a spray can Self-Etch primer to cover them before applying more 2K.

Action4478 · #5 (**permalink**) 10-29-2009, 07:42 PM

Ironically , when I am finish sanding to paint , I never have anything protruding from the surfacer. I don't much care for bulls eyes

Quote:

and i think i screwed up, i apparently didn't put on the usual 2-3 wet coats on my driver door.

Once the Primer is open , nothing will protect from the solvents in the finish from seeping under the edge of the of the primed layer ,(except more primer) sealers , unless catalyzed & dried (& sanded properly ) are a joke

Its a good thing some of the posters here , don't have to live with the results of their advice. They need to change the name of this section to the "Miss information department, read at your own risk"

e-tek · #6 (**permalink**) 10-29-2009, 08:29 PM

Quote:

Originally Posted by Action4478

Its a good thing some of the posters here , don't have to live with the results of their advice. They need to change the name of this section to the "Miss information department, read at your own risk"

It's too bad those who think their advise is so sound, have to sound like you!

gt350h · #7 (**permalink**) 10-29-2009, 10:17 PM

I totally agree with e-tek. So what you're saying beans is if you sanded through your high build to epoxy primer in a tiny area you have to mix more high build and spray it over that spot? Hmmm. What if you primed and sanded twice and on your second prime you sanded through to your first prime. You're telling me you would prime again? Technically you would have "nothing to protect the solvents in the finish from seeping under the edge of the of the primed layer" and I guess it will explode.

Sand_Man · #8 (**permalink**) 10-30-2009, 12:10 AM

I'm with you two, I guess we'll all jump on the "mis-information train"...

Ohio Ford Farm · #9 (**permalink**) 10-30-2009, 10:26 AM

Quote:

Originally Posted by Sand_Man

In my opinion, you don't need to do anything. The epoxy is there to protect the sheetmetal from rust, right? The high-build primer is there to give you something to block-sand to level the surface. So if you accidently expose some epoxy, you won't hurt a thing. Now if you were to sand to bare metal, then you'd need to lay down a bit more epoxy, since most high-build primers are NOT water proof. I think you'll be fine as long as you (A) don't have any bare steel, and (B) make very sure you use a sealer prior to final paint.

Side Question If you were to D A down to bare sheet metal .. a LOT of area do you HAVE to use epoxy to protect? What if you just used high-build like 10 min after you were done D A and wiped everything down and keep the parts in a clean dry shop? I was not schooled on other primers then just the high build and get it on before it sat out in the open air too long.

I ask due to that's what I pretty much did with my truck cab. I D A the whole cab and doors to 1 scuff the old paint up and 2 scratches and light rust I just keep on going till it was shinny. Wiped the whole thing down with towels and blew it off with air gun, wiped once more, then put 3 layers of high build on. Do I need to redo it or?? I learned off a local truck driver that has painted a few of his own cars.

e-tek · #10 (**permalink**) 10-30-2009, 05:55 PM

Thought I replied to this earlier - must've forgot to hit send!

When you strip to bare metal, you lay down Etch primer, so it etches to the metal and ties in the 2K (high build) on top. As well, the Etch isn't porous, like 2K is, so it inhibits rust. If you sanded the original paint and broke through in a few small spots, no worries, but if you had a lot of metal showing, it "may" be a problem. I say "may", because if you keep it DRY (in a low humidity envt) you shouldn't have a rust problem - and once you get it top coated (paint) then you're likely OK. Of course most people wet sand with lots of water - so it's gonna get wet.
The problem will come if you roll that truck outside - or if it's humid in your shop, you can get moisture through to the metal. Many of us have seen rust under bondo, which is why some no suggest etch under filler too....I don't do that.

Should you redo your truck? That depends: Are you keeping the truck forever? Do you have the time and materials ($$) to redo it? Are you gonna get to blocking and final sanding, then apply a top coat soon? Can you dry sand (400) to finish instead of wet?

Action4478 · #11 (**permalink**) 10-30-2009, 06:22 PM

Quote:

Originally Posted by e-tek

It's too bad those who think their advise is so sound, have to sound like you!

Right back at ya ...

.

Actually , I was responding in my first post ,to his question. He didn't do as he normally does & sanded through unexpectedly . Others answered questions he didn't ask.

Jump on me as you wish , ( had a good laugh),I was just trying to help the OP... Do you guys sand a panel & often sand through in numerous places (other than maybe an edge?...It sounded to me , like he wasn't done with the body work yet . When doing a complete , it is possible to let a panel get past you if you don't do this every day.
If he sealed & painted a bumpy panel, because he missed a step , he would not be happy in paint . (especially if it exploded while spraying)

e-tek · #12 (**permalink**) 10-30-2009, 08:08 PM

Quote:

Originally Posted by Action4478

Right back at ya ...

.

Actually , I was responding in my first post ,to his question. He didn't do as he normally does & sanded through unexpectedly . Others answered questions he didn't ask.

Jump on me as you wish , ( had a good laugh),I was just trying to help the OP... Do you guys sand a panel & often sand through in numerous places (other than maybe an edge?...It sounded to me , like he wasn't done with the body work yet . When doing a complete , it is possible to let a panel get past you if you don't do this every day.
If he sealed & painted a bumpy panel, because he missed a step , he would not be happy in paint . (especially if it exploded while spraying)

But ya gotta understand - lots of people here (any general forum) are beginners, don't do much of a particular job - or step - and if ya can't be kind to someone who's trying to get something done for the first, second or third time....then

But I hear what yer saying - and I'm sure the OP would have no problem if you had suggested he go back a step and make sure the panel was straight before applying more high build.

Action4478 · #13 (**permalink**) 10-31-2009, 01:17 PM

Quote:

Originally Posted by e-tek

But ya gotta understand - lots of people here (any general forum) are beginners, don't do much of a particular job - or step
Actually , I do know most are beginners , or they wouldn't need to ask

- and if ya can't be kind to someone who's trying to get something done for the first, second or third time....then

I missed the part where I was unkind , he said he may have left out a step , I agreed ,(use more primer)

But I hear what yer saying - and I'm sure the OP would have no problem if you had suggested he go back a step and make sure the panel was straight before applying more high build.

I assumed he had already done the blocking on the panel.I thought all he needed was more primer

e-tek · #14 (**permalink**) 10-31-2009, 11:19 PM

Action - sounds as though you and I are "misunderstanding" eachother! My apologies for taking anything you typed the wrong way. Cheers..