What's best to use on bare metal??

[sixpack_sid]

I am restoring a '68 Charger. I sanded the roof down to bare metal and there is rust peppered throughout the roof. I am planning to sandblast the roof to remove the metal. What should I put on the metal afterwards?  I spoke to the guy at the paint supply store and he told me to spray with etch primer and use a filler primer after. That's going to cost me about $200. Anyone know if this is the best way to do it or does anyone have any other suggestions? Any cheaper suggestions?
Thanks!

[tan top]

nope .. etch primer & filler primer  ..is by far the best way to do it ... would not do it any other way my self  !!

[69*F5*SE]

How do you feel about epoxy primer?

[Bobs69]

etch primer aka vinyl wash aka zinc chromate.  So I've been told.  The zinc has acid that bonds to the metal I believe.  Again, I'm just a hobbyist too, but I talk to people about it and that's what I've been told.

[hemi-hampton]

I like to use a self etching Wash Primer followed by a Epoxy Primer. LEON.

[chargerscott]

would you use self etching primer from a spray can? it might be a dumb question.

[Captain D]

I just finished sanding my 69' Charger down to the bare metal as well. I sanded down the ENTIRE car down to the metal. It took me about 3 months to do it, but it's worth it. A friend of mine recommended that I just sand it down to get it smooth, but getting it down to the bare metal really helps you to sand out the smallest lil' rust spots, as well as sand away any bondo to see whats under it, like rust, to treat it and seal it up. My 69' was a reddish-orange underneath, which was ironic because I'm restoring mine to be a General Lee.

Between the countless amount of sandpaper for the electric sander, primers, etc. at least $200 sounds about right. After I got it down to the bare metal, I actually used Rust Fix Rust sealer by DupliColor, allowed it to dry for a good 24 hours, then treated it with Duplicolor Self-Etching Primer (spray cans can be found even at Wal-Mart), then the Duplicolor Filler primer (also sold at Wal-Mart). You can apply bondo/filler if needed once you have at least the elf-etching primer the metal on I would think. The self-etch primer dries really fast too.

Best wishes and keep us updated!
Aaron

[superbirdtom]

You know that I can strip an entire exterior of a car in 1 day. all you have to use is an 8 inch soft pad that uses the 8 inch stikit discs. depending on the ammounts of paint bondo etc some areas might require 36 grit till you see bare metal start to appear , then switch to 80grit 8 inch stikit discs. use the scotchbrite black stripper wheels in areas you can't get at with the stripper pad. This method is good for an exterior redo . then if you have rust pits of course the best thing to do is use sandblasting to et as much out as possible , but if not the acid self etch primers will helf inhibit it . BUT then I would use rust encapsulation primer from por-15 or eastwood. of course you have to topcoat it .  A guy here did a challenger that had ruet pitting over the entire car and it was deep. he sandblasted it and went right over it with some eastwood rust encapsulator. I was skeptical. but by god it still looks good to this day and that had to be 17 years ago. -SBT

[Indicted]

would you use self etching primer from a spray can? it might be a dumb question.

Yes, on small things...like a door hinge that was dipped in muriatic acid for example. But an entire car, no, use the proper size.

[superbirdtom]

yes the best thing to ever come out of a rattle can is self etch for small parts i use the duplicolor brand green..  but for large parts an cars u need a catalyzed etch primer.

[bill440rt]

I would do the following:

1) Sandblast the car.
2) Blow it out ENTIRELY, in and out.
3) Spray it with a good metal conditioner, DuPont makes a good one. Let this flash, & wipe dry.
4) Apply a GOOD, catalyzed epoxy primer, such as PPG DP.

Don't play around with rattle cans or "miracle" rust preventers for the outside of the car. Leave the rattle cans for small parts & such.

[AKcharger]

Yet another option is use an epoxy primer/sealer (I'm using PPG DP90LF for my '72 vinyl top repair)...one step corrosion protection and sealing. Just hit it with top coat and you're done. I believe this is THE way to go if you have a large bare surface with little to no body work to do. Saves buying:
- Self etching primer
- Filler primer
- Primer Sealer

[bearbqd]

would you use self etching primer from a spray can? it might be a dumb question.

Holy crap, is that your foot in your avatar? What happened?

[Captain D]

Since I'm rather new at this, please excuse my ignorance with these questions:

1.) At this point, I'm leaning towards the PPG DP90LF. I've heard that POR 15 is pretty good stuff. Do they make a primer that is equivalent to the PPG DP90LF just out of curiosity?

2.) I've heard that the etching primer is good as a base coat, then the PPG DP90LF can be applied in order to promote better adhesion. Is this correct?

3.) Just to double-check that I'm looking at the right thing, is this what we're talking about: https://buyat.ppg.com/refinishProductCatalog/ViewProduct.aspx?ProductID=c98c3f28-89c5-467d-9983-e87c240f4c09

4.) Can someone please explain the mixing proportions/directions to this newbie?

5.) How is the PPG DP90LF applied to the car? It's not painted on by hand...it's sprayed?

6.) Once applied, a topcoat is to be used? If so, is anything else applied further (after the topcoat) before the actual paint job?

7.) And lastly, can the POR 15 "Rust Preventative Paint" be used inside engine bays or should a high temp. paint, such as the POR 15 "Heat Resistant Paint," be used inside the engine bays?

Thank you for taking the time to answer my loaded questions,
Aaron

[Bobs69]

I'm on my way out soon but I will say.............. I'm quite the amateur as well.  I didn't like the PPG measuring cups.  It's too "busy".  Way too many numbers and lines on it.  Can't remember exactly what but I remember not being able to find the mixing instructions for something.   Anyhow, I used this other stuff that was an additive to the paint for plastic bumbers;  it made it more flexible and as soon as you opened the bottle it only had a life span of 14 days or so then it's garbage I guess.  Now the instructions for this stuff said to add 25% of it to the totatl paint you had ready to go.  Of course their mixing cup didn't have this outlined, but using the METRIC SYSTEM it is easy to figure out.   Say 1000ml (1 litre) of product(paint hardner and reducer) ad 250ml of additive.  Did I get that right?  Anyhow.

Also, like I said I'm amateur.  You don't need to be a chemist to mix the primer.  Primer, hardner and reducer.  And the amount of reducer was optional depending on what sort of thickness you wanted, or how much you wanted it to build.  You could use no reducer but you'd have to spray it within 20 minutes.  So it just seamed kinda cheap.

I used dupont centari once or twice in the past, they gave you a metal measuring stick with 3 columns and, well it was idiot proof.

[AKcharger]

Howdy Cap'n

Here's some answers:

1.) At this point, I'm leaning towards the PPG DP90LF. I've heard that POR 15 is pretty good stuff. Do they make a primer that is equivalent to the PPG DP90LF just out of curiosity? POR 15 has a whole line of stuff BUT I'd suggest using their rust treatment and that's it (I used Eastwoods rust encapsulator before..works good) My concern would be compatibility. If you start mix-n-matching primers and such from diffrent company you may run into problems, it's a long shot but after all that work and expense of a paint job I'd hate to see it bubble or peel within a year because or chemical incompatibility

2.) I've heard that the etching primer is good as a base coat, then the PPG DP90LF can be applied in order to promote better adhesion. Is this correct?  Well to be honest till I bought this stuff I always heard you needed etching primer, epoxy primer, fill primer and sealer. According to the info pamphlet this stuff does it all. Can apply to cleaned and sanded steel or host of other topcoats and it can be top coated with additional primer or straight PPG base coats lines (I didn't see OMNI listed however?)

3.) Just to double-check that I'm looking at the right thing, is this what we're talking about: https://buyat.ppg.com/refinishProductCatalog/ViewProduct.aspx?ProductID=c98c3f28-89c5-467d-9983-e87c240f4c09 Site wouldn't open properly but if its Deltron P-196...that's it!

4.) Can someone please explain the mixing proportions/directions to this newbie? Easy 2 parts primer to one part hardener or catalyst...reducer is optional. you can ask for diffrent mixing cups at your paint supplier

5.) How is the PPG DP90LF applied to the car? It's not painted on by hand...it's sprayed?   I Guess you could paint it with a brush, but MAN would that be an AWFUL surface to try to paint over...no, consider that you must spray it with a paint weapon (gun)

6.) Once applied, a topcoat is to be used? If so, is anything else applied further (after the topcoat) before the actual paint job? If you body work is perfect then no, scuff with a scottchbrite® pad (green scrubbie) wipe down with a tack cloth and shot your base coat color and then you clear coats (or just color if you using a single stage) I STRONGLY suspect you will need sanding so in that case you'll need a few coats of fill primer (PPG K38)...One coat fill primer, block sand smooth...another coat of fill primer, block sand smooth ect. (I've always done 3 fill/block coats) since you will have been adding filler here and there in the blocking process you'll need to "seal" the primer(PPG K93) then shoot your color

7.) And lastly, can the POR 15 "Rust Preventative Paint" be used inside engine bays or should a high temp. paint, such as the POR 15 "Heat Resistant Paint," be used inside the engine bays? Nah engine bays are tough, regular paint will be fine...why would you want to use POR 15 in there anyway? Do you have rust in the engine bay area?

Your welcome for taking the time to answer my your loaded questions,

Bill

[BlueSS454]

Epoxy primer is the best thing to use over bare metal.  I use DuPont 2540S and have had very good results.  The PPG DP90LF is a high end epoxy also and there is another one out there made by Southern Polyurethanes (SPI).  Etching primer is outdated technology and not needed over bare metal. 
The purpose of an etch primer is to promote adhesion on previous topcoats and substrates (laquer paints mainly).  When you have blasted or sanded bare metal...it's not needed.  Most epoxy primers are a 2:1 mix ratio.  2 parts primer to 1 part hardener. 
You can get a cup with the mix ratios on it anywhere for $1.  All mixed eppoxy primers must be sprayed with a paint gun.  you can pickup a cheap gravity gun anywhere that sells tools.  You will also need AT least a 1.7 mil tip to spray it. 
Once you apply the epoxy primer and it cures, you can do all your plastic filler work over top of it.  I like to scuff the area I will be applying filler to with some 80 grit, but DO NOT take it back to bare metal, just a scuff will do.  Once your filler work is done, you can apply some high build primer to begin the blocking process.  Once that is done, apply a final coat of epoxy primer to seal the bodywork.  There are specific instructions on the amount of time that needs to lapse before you topcoat it.  Alot of them have a 3-5 day window before sanding will be required.  You can also use it as a wet on wet sealer which means you apply the epoxy wait 1 hour, then apply your top coat. 
Use the same process in the engine bay.  You don't need to use high temp paint there. 
Lastly, the only place POR 15 belongs is in the trash can.  It's not a "rust preventive paint", it stands for Paint Over Rust...something that should not be done......EVER.

[Charger-Bodie]

Epoxy primer is the best thing to use over bare metal.  I use DuPont 2540S and have had very good results.  The PPG DP90LF is a high end epoxy also and there is another one out there made by Southern Polyurethanes (SPI).  Etching primer is outdated technology and not needed over bare metal. 
The purpose of an etch primer is to promote adhesion on previous topcoats and substrates (laquer paints mainly).  When you have blasted or sanded bare metal...it's not needed.  Most epoxy primers are a 2:1 mix ratio.  2 parts primer to 1 part hardener. 
You can get a cup with the mix ratios on it anywhere for $1.  All mixed eppoxy primers must be sprayed with a paint gun.  you can pickup a cheap gravity gun anywhere that sells tools.  You will also need AT least a 1.7 mil tip to spray it. 
Once you apply the epoxy primer and it cures, you can do all your plastic filler work over top of it.  I like to scuff the area I will be applying filler to with some 80 grit, but DO NOT take it back to bare metal, just a scuff will do.  Once your filler work is done, you can apply some high build primer to begin the blocking process.  Once that is done, apply a final coat of epoxy primer to seal the bodywork.  There are specific instructions on the amount of time that needs to lapse before you topcoat it.  Alot of them have a 3-5 day window before sanding will be required.  You can also use it as a wet on wet sealer which means you apply the epoxy wait 1 hour, then apply your top coat. 
Use the same process in the engine bay.  You don't need to use high temp paint there. 
Lastly, the only place POR 15 belongs is in the trash can.  It's not a "rust preventive paint", it stands for Paint Over Rust...something that should not be done......EVER.

Well said! .......and one other thing Id like to add is that Epoxy sticks far better to bare steel than it does etch primer.......Alot of the guys that use both are doing so to try to make the job even better, And hats off to them! BUT its actually quite the opposite.Epoxy is just plain the better product!

[daytonalo]

WELL SAID POR 15 IS FOR A THIRD GRADER , PLAIN GARBAGE , SHORT CUT ALLEY!!! SANDBLAST . SANDBLAST , SANDBLAST !!!!

[Captain D]

Thank you for the messages! EXCELLENT info here!

Yeah, there seems to be different opinions as far as primers go, etc. But, I am definitely interested in the PPG DP90LF.

1.) To do a 69' Charger, how much of the PPG DP90LF + mixes would I need?
2.) How much cost would we be looking at?
3.) Where might I find the most economically priced spray gun for this project?

Since it seems that it takes a few days to dry/treated properly, I'm in need of a dry garage to do the work. I certainly don't want to do any of the work outside. My garage is the greatest...very tight. I can see about one of my neighbors who has a nice garage and has restored many vehicles. If he is willing to do it, he may have the spray gun(s), but I would need to let him know the details from the first two questions above. Thank you for your opinions and ballpark figures...

aaron

[chargerscott]

ok are we saying use epoxy primer over bare metal? i don't want to do this again

[69*F5*SE]

Yes, epoxy over prepared bare metal.   

[BlueSS454]

ok are we saying use epoxy primer over bare metal? i don't want to do this again

Yes 
If you buy a gallon of primer, plus 2 quarts of hardener/activator, it will be MORE THAN ENOUGH to do 1 car.  You'll still have some leftover after the second application.  Remember, lay 1 coat down on the bare metal to seal it, the 1 more coat once you are done all your filler work and high build primer block work to seal the bodywork in.  I only went through a half gallon of the DuPont 2540S epoxy after using it for 2 coats on the Charger and 1 coat on a Chevelle I'm working on.

[375instroke]

If one reads the PPG tech sheets, etch primer is for bare metal.  Also, the etch is not to be used on media blasted metal.  Can someone explain why?  I don't know, but that's what the tech sheets say.  The DP epoxys can not be used on PPG DPX170, or DPX171 etch primers, but can on DX1791.  Read the sheets of both products you want to use to check compatibility.  I think the etch primers are the easy way out, and the tech sheets say they are for faster throughput, lower inventory, and higher productivity, and the metal conditioners say they are for maximum adhesion and corrosion prevention.  I prefer the PPG DX579 metal cleaner, then DX520 metal conditioner, followed by DPLF epoxy primer.  Here are links to the etch primers:
DPX170/171
DX1791

[superbirdtom]

I believe that the finish is too smooth after some media blasting ,and it actually peens the surface making it stronger and resistant to the etching chemicals to absorp into the surface.  you need to rough the surface up a bitI like just buzzing over the surface with 100 grit d.a on steel.       just like aluminum. If you strip some aircraft that have factory paint over them like cessna it is an enamel ,after applying stripper it drops right off leaving a shiny aluminum surface . after a thorough pressure washing . before you etch and alodine it. you take red scotchbrite and scrub the hell outta it with soap. this opens up the alclad and the etch and alodine will bite in .

It is the same with steel. I have had cars come to me with paint bondo work popping off of it, and what I found out was the guy who did the body and paint tried to sand metal smooth with going from 150 to 220 to 320 to 400 to 600 . my god the metal was almost polished.

I always etch prime first and have never had any problem with it. but just epoxy priming works good too. either way. When I get the whole body ready for high fill primer I use a 2 qt pressure pot to spray the primer on, It goes 4 times as fast. and overspray is very minimal more product goes on the car.    good advise on checking out the tech sheets as theirs so many products that most have ever heard of and how to use properly where the company will warranty problems if used according to tech sheets. 

[hemi-hampton]

If you read the tech sheets you'll notice a NOTE: or small print at bottom saying" Film build of 1.2-1.5 mils of DPLF is Required, or the surface must be treated with metal cleaner/conditioner or coated with DX1791/1792" I think it takes 2 coats to provide 1.2-1.5 mils. So from what the tech sheet is saying, if your only putting 1 coat of DP epoxy on you better (Wash) Etch prime or metal condition. Seems some people have not read this small print?  You would not want to prime over blasted metal that has been blasted with baking soda, walnut shells or any other very fine blasting method. On interior blasted parts I usually sand with 80 grit & definately on exterior. 80 grit sanding on metal is not the same as 80 grit sanding on painted or primed parts. LEON.

[BlueSS454]

Etch primers were used for just that...etching, or biting into previous topcoats or substrates in order to get the new material to stick to the old.  With blasted metal, it's already etched therefore no need for an etch primer.  Etch primers were generally used for refinishing old laquer paint jobs. 

If one reads the PPG tech sheets, etch primer is for bare metal.  Also, the etch is not to be used on media blasted metal.  Can someone explain why?  I don't know, but that's what the tech sheets say.  The DP epoxys can not be used on PPG DPX170, or DPX171 etch primers, but can on DX1791.  Read the sheets of both products you want to use to check compatibility.  I think the etch primers are the easy way out, and the tech sheets say they are for faster throughput, lower inventory, and higher productivity, and the metal conditioners say they are for maximum adhesion and corrosion prevention.  I prefer the PPG DX579 metal cleaner, then DX520 metal conditioner, followed by DPLF epoxy primer.  Here are links to the etch primers:
DPX170/171
DX1791

[hemi-hampton]

As far as I know the etch primer for bare metal only & not old sustrates, Old substrates such as Laquer or any other paint needs to be sanded, Once sanded, this sanding provides the adhesion needed, so no need for a Etch primer. Just my LEON.

[superbirdtom]

Etch primers were used for just that...etching, or biting into previous topcoats or substrates in order to get the new material to stick to the old.  With blasted metal, it's already etched therefore no need for an etch primer.  Etch primers were generally used for refinishing old laquer paint jobs. 

If one reads the PPG tech sheets, etch primer is for bare metal.  Also, the etch is not to be used on media blasted metal.  Can someone explain why?  I don't know, but that's what the tech sheets say.  The DP epoxys can not be used on PPG DPX170, or DPX171 etch primers, but can on DX1791.  Read the sheets of both products you want to use to check compatibility.  I think the etch primers are the easy way out, and the tech sheets say they are for faster throughput, lower inventory, and higher productivity, and the metal conditioners say they are for maximum adhesion and corrosion prevention.  I prefer the PPG DX579 metal cleaner, then DX520 metal conditioner, followed by DPLF epoxy primer.  Here are links to the etch primers:
DPX170/171
DX1791

>>>>>>>>>>>>>>>>>>>>>>>I believe what you are thinking of is adhesion promotors. which have been around for 25  years or so.