SPI primer and polyester primer questions.

roger1

Member
I installed partial patch panels on my GTO project on the quarters at the wheel well openings. I butt welded them in and finished them off the best I could with a spoon, dolly and shrinking disc. Very challenging since the inside access for a dolly is not good.
I sprayed 2 coats of epoxy primer on the entire body yesterday. My intention is spray Slick Sand polyester primer over the patch panel areas but I decided to use a little filler first and put some on and sanded it today.

Before spraying:

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And now:

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I thought it looked good when it was bare metal but there's nothing like black epoxy to make it look kind of bad. Anyway, I was going to spray the Slick Sand today but after looking at it this morning, I thought it would be better to use so the filler some first. Maybe I should have just hammered on a few coats of the polyester as now I'm faced with having to ask a couple questions here. I want to be safe with this car. This car is a keeper for me and I'm going to strive for a show quality paint job. It is going to be SPI Dark Red with Universal Clear.

1. I sanded through the primer down to metal in several small spots. Now I am unsure of whether I can spray the Slick Sand on these areas tomorrow or whether I should spot spray epoxy over these areas and wait until Monday to spray the Slick Sand. The Evercoat instructions say I can spray over sanded through areas as long as the spots are not over an inch in size. All of the spots I have are smaller than that but I trust you guys here more than what Evercoat says. What would y'all do?

2: If the answer is spot spray more epoxy, then that leads me to this question about my time window. I've always kind of felt that the 7 day recoat window on epoxy was more for temperatures on the cooler side. My shop gets into the low 90s during the day and in the 80s at night. With those temperatures, how long do I have to spray polyester over epoxy without having to another coat of epoxy on the car first? Monday will be the 3rd day.
 
What Evercoat says on their TDS holds true more for collision repair and used car work. Not for high end restoration work. So after your filler work over epoxy, you always want to put at least one, preferably two more coats of epoxy over your filler work. Then wait 48 hours and apply the poly primer.

You are doing a great job on this car BTW. :)
 
Thank you Chris, that is what I will do. Got a feeling on my 2nd question?
My gut is telling me to spot spray epoxy over the filler and then do a coat on the entire body. That will start my window over again and the filler will have 2 coats over it.
 
I've had some small sand throughs to metal & sprayed g-2 over, looked fine years later painted black. But safer is safer.

Them fender flare areas are fun, ain't they.

I love using the g-2 spray within certain parameters, but where you're working on I'd definitely have done the same & just started with filler first. Could have done some sprayable first & with restraint, stopped sanding & done a light coat of metal glaze before hitting metal. But the reality of areas like that is you're so likely to sand through somewhere at the stage you're at, best just keep doing it as you are & save the sprayable filler for later. Definitely great to spray another coat of epoxy first, but I'd probably give the whole thing just a quick as possible light swipe with some course grit to highlight any bad highs or lows before proceeding. I'd also probably double or triple up on epoxy coats in the bad areas where sand through is more likely, as well as in low spots highlighted by a quick scuff. You got the right weather for the epoxy to kick over fast & not slow you up.
 
Thanks again Chris. And thanks for your compliment too. I get lots of them on my build thread but means a lot coming from a pro.

Thanks for your thoughts on this too Joe. You always have good ones for me.

And yes, those wheel well flares were a pain in the butt and the hardest patch panels I've ever done. My wife helped me with holding a dolly. I should have gotten a photo of her laying down in the trunk!
I also had to fabricate a couple of dollies to get them to fit into the areas over the middle of the flare. I toyed with the idea of removing the quarters to do them. But ultimately I think I got it pretty good the way I did it. They don't make complete quarters for '68-69 GTO convertibles and not sure I would have gone that way even if they did. I always try to keep as much original metal as I can. The perimeters of the outer wheelhouses were trashed too. I bought a pair of those but the fit was so terrible I didn't use them and just fabricated the rusted portions from 18 gauge sheetmetal. There were some issues with the inner wheelhouse too where they attach to the trunk floor flanges. I fabricated what I needed there too.
This whole process really took a toll on my back. At one point I had to rest it for a week. My aches and pains from age are really starting to kick in now that I'm 66.

I was already thinking what you said here about checking the rest of the car at this point. I knew the car had some door dings and some hail dings but not this many! Black epoxy sure points them all out. I've already added more filler and might as well do more of that today as there are more spots I haven't hit yet.

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And btw, I just bought a new spray gun for spraying polyester primer. It's an Iwata Air Gunsa with a 3.0 mm tip. I ran across a youtube video where the guy uses one for spraying both G2 and Slick Sand. It sure looks like it sprays it way better and faster than the DeVilbiss 2.2 tip gun that I had been using. Plus, I was a little concerned with shooting poly with it being in the 90s so I liked the idea of being able to go faster.

 
I always find it better use of your time & materials to at least quick sand an unsanded area rather than just spraying it again. Otherwise it's a lost opportunity to get any heavier spots out the way & be able to get to your final true block sanding. Being interrupted by pesky deeper spots OR high spots that make you have to respray & start over really add to your time when you should be just fine tuning.
I used a Titan 6 stage turbine I have at work last few times I sprayed epoxy & g-2. Turbines use a smaller tip than pneumatic, which helps it lay down smoother. You may be sanding primer anyway, but it spraying rougher adds sanding time & takes more material. Hope you like the new gun.

If not doing so already, would be good to learn some more stretches that will work for you personally for your back & everywhere else, as well as making yourself stop every so often for a few quick stretches while working. Right now I'm struggling to make it to age 66.:( Seriously.
 
I ended up doing what you suggested Joe and blocked the entire car with 180 before a respray with epoxy followed by the Slick Sand.
After sanding the Slick Sand areas with 80 followed by 180, I had to do some additional epoxy and more Slick Sand in a few areas. Even did a third iteration of that on the quarters. Some of that was because I wasn't sanding it correctly at first.

The side shapes on this GTO are complicated and a lot different from any car I've done before. I spent a lot of time figuring out how to sand it and got some good advice from a guy who did a concours quality '68 GTO convertible. It has 2 cigar shaped protrusions down the middle of each side (cigars that are pinched on both ends). One that starts on the front fender and ends about 3/4 the way back on the door and one that starts about 6" back from the door edge on the quarter panel and ends at the rear of the quarter. The pinched ends of the protrusions have to be sanded-in with blocking at an angle to make sure the shapes maintain the pinched ends of the shape correctly.
I am sure glad I had bought a 27" AFS sanding block before the company went out of business. It's the one with a steel plate on the bottom of the foam body and has 3 removable steel bars for the adjustment of the bending tension. It was the perfect block for getting the arc correct for the center parts of the cigar shapes. This process has taken me a bunch of time. Many hours of work since my last post here 3 weeks ago.

I've now got the body to where I think it has no defects or high or low spots and just needs a final finesse blocking. Gaps and panel to panel levels are perfect. My plan is to shoot a single coat of epoxy today (2 or 3 on the top and sides of the front bumper) followed by a couple of coats of Turbo 2K at 4:1:1 tomorrow. I'll tape off the bumper before spraying the Turbo.

So here are photos I took late yesterday. I only used the Slick Sand where there was metal work done and to help with panel to panel level matching. I don't have any filler on the car other than the Slick Sand itself and some USC Icing. Most of the Slick Sand isn't very thick. Thickest places are on the quarters and the top of the d/s fender. I made sure the edges of the doors, hood and trunk lid have very little to no build with it.

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Thanks for the vote of approval on my plans guys!
Btw, I have a new primer gun since I have sprayed Turbo primer last. It's a Devilbiss FLG-678 primer gun and came with a 1.8 and a 2.2 tip. Which one would be better with Turbo mixed at 4:1:1?
 
Thanks. I'll see how this gun does with it with the 1.8. I opened a can last night to stir and man it is thick!

I got it sprayed with epoxy yesterday. I do see a couple of places where it doesn't reflect quite right. One on the hood in the middle of the P/S and the top part of the P/S quarter. I may put a 3rd coat of Turbo on in just those 2 areas.
I have rolls of 120 and 180 but I don't have any 150 on hand. Would I be OK starting with 120 followed by 180? Maybe just use the 120 on the couple of areas that have 3 coats?
After I get it to what I consider perfect, my plan was to spray a final 2 coats of epoxy reduced a bit and block that with 320 then 400 to fill any sand scratches I might have missed on the Turbo.

I switched to using red epoxy this time only because I have more of it on hand than I do black.

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I've been out in the shop early this morning and think I just answered my own question with blocking grit after I spray the Turbo.
Yesterday, when I sprayed the epoxy and saw the couple of areas of reflections I didn't like, I put a second coat of epoxy on those areas. I just hit them with my 27" block with 180 on it (steel bars removed) and lightly dragged it criss-cross over the 2 areas. I think I've already got the areas half way to corrected. After spraying the Turbo, I should be able to easily get it perfect blocking with 180 which is good as I really didn't want to introduce any sand scratches deeper than 180 at this stage.
 
Looks like you are well on your way to doing that---once again. I, for one, can appreciate the work you put into getting the panels level across the seam, and consistant gaps throughout the car. Well Done!
I agree! Looking good.
It is always disappointing to see a nice car with great paint but poor panel alignment.
I think this is an area worth obsessing over.
 
Looks like you are well on your way to doing that---once again. I, for one, can appreciate the work you put into getting the panels level across the seam, and consistant gaps throughout the car. Well Done!

I agree! Looking good.
It is always disappointing to see a nice car with great paint but poor panel alignment.
I think this is an area worth obsessing over.

Thanks guys! Gaps and levels have always been important to me and the first thing my eyes go to on any car. I have said many times that I'd rather see a car with good panel alignment with paint flaws than the other way around. Any car that gets driven will get some paint flaws over time but excellent panel alignment can always be enjoyed.

So I got the Turbo primer sprayed on yesterday. It sprayed pretty nice using my primer gun with the 1.8 tip. I sprayed 2 full coats then a 3rd on the few areas I talked about earlier. It's nice to see my car in one color again and now I can block sand it using some guide coat.

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That's not looking like it will be a very friendly paint job when you're done, doesn't look like it will wave to anyone when driving by. :p

Seriously though, best I can see on my HD monitor, she's looking pretty good now. I'm sure you're glad to be switching to finer paper now.

I know you like stock look, but personally I don't consider it a completely stock body anymore. Stock never looked that good.

You can give some credit to fancy sanding blocks. but it's still the technician holding the blocks that made it look so nice.

Can't wait to see in paint. Keep it up my friend.
 
just a thought but i never spot prime anything . thin edges can come back to bite you . but thats just me .
 
That's not looking like it will be a very friendly paint job when you're done, doesn't look like it will wave to anyone when driving by. :p
Seriously though, best I can see on my HD monitor, she's looking pretty good now. I'm sure you're glad to be switching to finer paper now.
I know you like stock look, but personally I don't consider it a completely stock body anymore. Stock never looked that good.
You can give some credit to fancy sanding blocks. but it's still the technician holding the blocks that made it look so nice.
Can't wait to see in paint. Keep it up my friend.
Thanks for the compliments Joe!
Yeah, I think it does add a bit of a custom look to tighten up the gaps some and get the panel level match perfect but in a subtle way. I did that to my El Camino too. I hope the tighter gaps don't come back to bite me on this convertible with frame flexing. I'm also a bit concerned that the gaps might change a bit when the extra weight from the interior and the rest of the components get added.

Yes, I thought it was looking really good after shooting the body and getting it one color with the Turbo. My hope was not to get any sand throughs but no such luck. I've been blocking it and have sanded through in several spots. I've also found myself readjusting the pinched ends of the cigar shapes on the quarter panels some. Here's a photo of the most complicated place. This is that '68 GTO I talked about earlier. Very challenging on how to block sand this shape when a patch panel has been installed around the perimeter of wheel opening.

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And btw. Yes I have been doing back stretches but not as much as I should. I bought a new creeper that has really helped too. This works well for block sanding down low on the sides of the car:

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just a thought but i never spot prime anything . thin edges can come back to bite you . but thats just me .
I've been thinking about what you said here. I don't think I've done that up to this point other than to spot spray epoxy let it flash and follow with an all over coat. It seems to me the issue would be that a spot spray will be dry on the edges and the edges in turn wouldn't have good adhesion. But it also seems to me that if they are block sanded back to a feather edge, adhesion would be good at the resulting edge. Do you agree with that?
And if the final coat of primer is epoxy, it seems that those feather edges would be kind of locked down with that.
 
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