[dataway]

Can you guys offer me some good reasons to use epoxy primer over a stripped, bare metal body compared to conventional (2k?) or 1k primer?

Recently I've watched some videos of people working on high end cars and they don't seem to be a fan of epoxy primer, mostly centered around doing future body/metal work on a car that has it.

Bear in mind I'll be dead in 20 years so 50 year durability is not a big factor for me And for a car that will be stored indoors and probably never see rain or salt I'm not seeing a lot of advantage unless it provides other qualities superior to conventional primer as far as promoting adhesion of paint or filler, providing a smoother finish or something of that nature.

I'm assuming conventional primer is still used by the majority of painters?

[RamblerRacer]

You would be fine with a 2K that is listed as a DTM (Direct To Metal)
I went that route on one of my projects and have also used epoxy.
My only qualifier is the condition of the bare metal.
If you have pitting or had light surface rust I would spend the extra on the epoxy.
Keep in mind the epoxy is typically even nastier than even 2K

JT

[nytrainer]

Originally Posted by dataway

Can you guys offer me some good reasons to use epoxy primer over a stripped, bare metal body compared to conventional (2k?) or 1k primer?.......

Johnny I see NO reason not to use epoxy. It will protect the metal and you can fill over it. Sands beautifully. You can shoot 2k urethane primer over it if you feel you need to block more but the SPI epoxy (only epoxy I can talk to from experience) does build somewhat and is a dream to dry block sand. If the car is going to sit for anytime before actually shooting color I would not want to leave it in just primer. I’ve epoxy primed hoods etc and came back to the project months later. Just a quick scuff and recoat (or just scuff/seal if ready to paint) is all that’s needed.
You can also use it (SPI epoxy reduced) as a sealer before base or single stage.
A 1 gallon kit (uses 1:1 mix with activator) is roughly $200.
I don’t even know of a good 2k DTM (but I’m sure they’re out there) and if by 1k you’re referring to a lacquer primer those days are long over IMO.
Only negative I can think of is panels need to be a minimum of 60 degrees so cold weather requires a heated space and collision shops with fast turnarounds would probably opt for something faster.
Use the SPI forum as just about any question you can think of has been answered there.

[tjs72lemans]

Epoxy primer is moisture resistant. I'm not sure about 2k. So, you can leave panels in epoxy prime condition for long periods without worry of moisture getting to metal underneath. It sands terribly. But, the SPI I used last year for first time, does sand wonderfully. It's not an epoxy primer from what I understand. Nothing sticks better to a surface than epoxy primer.

[Formulabruce]

Don't use etching primer.
Use SPI epoxy.
Look at videos on the net.
I have used many, and SPI is the best . Its flexible, holds, has millage, and can use as a sealer over body work.
You can have disasters in 3 months with crappy 1 stage primer. Figure in humidity, temperature etc will affect the contraction and expansion of all finishing materials.
I bought an egg timer to make sure I wait 30 min for induction, and 30 min between coats.
In many cases you can skip high build primer on nice indented surfaces as you can put on more SPI and block it.
SPI has a Manual for their products, and tech support, AND a large forum to show and discuss issues.

[3 Chiefs]

I too am a big fan of SPI Southern Polyurethane Inc. Pay attention to the details. There is special things to consider before putting epoxy over soda blasted metal or metal that was treated with ospho. Other than that it is a primer that you lay down first. Put body filler over it. As you sand your filler you will expose bare metal on the outside of the repair. Cover it all again with epoxy and the naturally moisture absorbing filler is now encased in a epoxy seal. The stuff is great. We have all seen the rust that occurs between the sheet metal and filler on an old repair. With an epoxy bed laid down first that wont happen.

[roger1]

Originally Posted by dataway

Can you guys offer me some good reasons to use epoxy primer over a stripped, bare metal body compared to conventional (2k?) or 1k primer?

I'll reiterate what someone else said here.
There just plain isn't a reason not to use it over bare metal.

Originally Posted by dataway

I'm assuming conventional primer is still used by the majority of painters?

Urethane 2K primers are used by the majority of painters. But I'd say the majority use epoxy primer on bare metal when the car has been stripped. High end body shops that is. Body shops that only do collision work might be different.

I've been using SPI epoxy primer for over 15 years now. My rule is "epoxy first on everything". I always use the SPI reduced as a sealer right before the first color coat too.

SPI epoxy does block well but I prefer to do most of my blocking with polyester and urethane 2K primers. Polyester where I've done bodywork only and then all over with the urethane.

[dataway]

Do have some areas of pitting, and, there probably will be areas with factory applied or extremely old, very stable filler still on them.

So I do all my seam sealing AFTER epoxy?

Well, I guess I'll call SPI on Monday. Hopefully I can order quarts of black as I'll be doing smallish areas at a time.

Too many opinions I respect here to not listen to them.

[Formulabruce]

I have a nose for a 72 Firebird I am stripping to rubber. it has some cracks and the jack slipped and gouged it bad. I will post pics on the SPI forums and link it here. You'll see what an amazing job the SPI primer can do, even on raw endura rubber.
Due to the cost, ( 90 bucks for a quart WITH activator, Free UPS shipping) I try to do a panel at a time.
I also get the small mixing cups.
SPI will send you a painting product AND Instruction manual with their paint.
The Owner, and others) reply and answer questions on their Forums.

[dataway]

Since it's such a better deal in gallons ... how's the shelf life if I divide it up into quarts and seal it up?
How's coverage, what's typical for a full body?

[n20ta2]

I would use the epoxy. Scuff for body work, when your finished scuff the areas you didn't touch then epoxy again. I like to do my seam sealer at this point and if your quick about it you can spray your high build urethane within the adhesion window. I wait to do my seam sealer in the drip rails until a few days before paint so the high build doesn't build up and crack.

[roger1]

The shelf life of SPI epoxy is quite long. Opened activator shelf life is 3 years if stored at stable temperatures. So buying gallons is the way to go.
Pot life is pretty long too at about 3 days. And if you mix in some new with it, pot life starts over again.
http://www.spiuserforum.com/index.php?threads/epoxy-activator-shelf-life.4691/#post-51178

[Formulabruce]

Originally Posted by dataway

How's coverage, what's typical for a full body?

You'll want to use thin coats of Epoxy. You will wait 30 min after mixing for induction ( and Better UV protection).
You'll need 3 coats , and wait 30 min between coats. It will start to get shiny. It will lay down very flat unlike some others. This info is in the handbook they send you with your free UPS shipping. You can separate it out of a gallon, but must use Metal paint cans you can get at your local Napa. Don't get metal looking plastic cans at home cheapo.
Pic is a buddies nose and has 3 coats of SPI red oxide colored epoxy. Took 2 hours for that due to induction, and 30 min between coats.

[roger1]

Originally Posted by dataway

Do have some areas of pitting, and, there probably will be areas with factory applied or extremely old, very stable filler still on them.
So I do all my seam sealing AFTER epoxy?
Well, I guess I'll call SPI on Monday. Hopefully I can order quarts of black as I'll be doing smallish areas at a time.
Too many opinions I respect here to not listen to them.

If there is rust down in the pits on the outer body, you will want to get all the rust down in those pits removed. Absolutely remove all old filler!
Epoxy prime before seam sealer.

[tjs72lemans]

I had my 72 endura bumper sand blasted and the guy asked how I was going to get the rough surface smooth again. I told him after I spray it with SPI primer it will end up smooth again. It did. It took about three coats and re-sanding each time, but I was pleasantly surprised. This was the first time I used the stuff.

[Formulabruce]

You can fix rust pits with plain old vinegar, that won't leave any kind of phosphate or oxide. Keep it wet for 30 min, even if you need to tape a rag over it. Wash with dawn dish soap and water, and small brush . Thoroughly dry it off as a soon as you can. You can then use your SPI. epoxy if metal and paint Temps are both at least 70 degrees and not in direct sunlight

[roger1]

I would also wipe everything down with SPI 700-1 Waterborne W&G remover and give it ample time to completely dry before spraying your first coat of primer. I differ from Bruce a little in that I do spray light but wet coats of epoxy. You do want to make sure your gun is adjusted right and you don't get too close to the metal, especially on the first coat. It can mottle some if you do that. It doesn't cause problems but still best to try and avoid that.
I find that I get the best results when I use a 1.8 tip gun. I have a DeVilbiss gun designed for primer with interchangable 1.8 and 2.2 tips. I use the 2.2 for polyester primer.
You can spray SPI epoxy fairly well with a 1.4 tip too. And a 1.4 works the best for the reduced sealer coat and I use my Iwata guns for that.
Many people have decent results using cheap primer guns with SPI epoxy and I used to do that but I get better spraying results with the better guns. I don't have any of the cheap guns anymore.

[dataway]

OK, with all this info I have a plan now. Body is outside, pressure washed it today, bring it in tomorrow after another day in the sun. Will start sand blasting jams and such next sunny day.

What's a good method for removing old filler ... course paper on a DA? I think it's just skim coating in a few places, no dents or puller holes or anything on the inside.

Any particular color I should use under Verdora Green? Was planning on black so I can use it for the cowl and other areas. Is black harder to use with a guide coat of some sort?

[roger1]

Grey under green, But it really doesn't matter for anything under that. Just the sealer before color matters. I'd prefer red or black under poly or urethane as you can see it earlier if you block down to the epoxy base so you don't go all the way to bare metal.

[roger1]

On second thought. Get black. I forgot Verdero green is really dark. Better to use under your other primers and much better to have on hand because it can be used for so many other things. It's great for the underside of hoods and inner fenders. Just black primer them and you're done. When I use SPI epoxy this way I reduce it about 10 to 15% and use my Iwata 1.4 gun. I have both an LPH-400 and an LPH-101 which is a small touch-up type gut and both of them have 1.4 tips.
Reduced, it will lay down more smooth and is a little less glossy.

Here's the underside of the hood on my Bel Air.