Just bought a project 1972 911T

[Rodney Nelson]

I am in information overload with all of the choices with undercoating...

Monstaliner looks pretty good, but definitely not a factory look, I like the fact that it is tintable. One thing to note is that it is clear when you get it tinted so there is a better chance of it color matching the rest of the car.

UPOL / Raptor has a creamy color that will affect color matching a bit. UPOL/Raptor seems to be harder, less flexible. hard undercoating seems to be less desirable, you want more flex.

3M Schutz, is ruberized with Nitrile rubber. They do have one that is tintable, beige in color but I can't find any videos of people actually tinting it. this would replicate the factory being rubberized and beige in color...

Realistically, rubberized is the way to go if you want it to be an effective undercoating. Factory undercoating is extremely hard to remove via sandblasting because it bounces off compared other non-ruberized undercoatings.

Thing is that none of these will look factory, and I'm not sure looking factory is what I'm really after. Some of the rubberized coating up in the rear fenders of the 911 is like a half of an inch thick, with crazy texture! There is no way you can duplicate this.

Here is what I'm thinking I want...

I want color in the engine compartment with undercoating properties.
I want undercoating in some or all of the frunk, again with color
I want color in all of the wheel wells, under the bumpers and up a bit on the rockers.
I like the ease of using a tinted product because it saves a step in the process.
I am thinking of clear coating the colored undercoating as well.

After some of the comments I may pass on POR-15 as a rust barrier on the bottom, but realistically there is more positive comments about POR-15 than negative and the stuff is way more durable and made for rust prevention compared to a etch primer. I would never use it under paint. Just under undercoating. I'm just super worried about there being some rust that I didn't get to. It is like another layer of protection this car could definitely use. Using standard etch primer is no extra protection.

I'm pretty sure I will be using POR-15 on the inside. If you have watched Mikes Restorations videos on his 67 911, this is what he did, that guy is amazing and a total perfectionist. I'm most likely going to follow his lead on this one and then dynamat over the top of it.

One of my big questions is what should I do right now. I think I'm just going to leave the underside as is for now and move onto the rear fenders. All surfaces have been fast etched, it will not be rusting anytime soon for now... I hope.

We will revisit the undercoating as soon as I'm done with the rear fenders.

I will send out some more updates hopefully on Sunday night.

Thanks,

Rodney

[911-Hotrod]

You need to understand the cure mechanism for POR-15 and other paints.

1st - steel can hold moisture in its micro-surface texture. 2nd - paints are polymers that are not totally water resistant because all polymers absorb moisture into their molecular structure. Water molecules can migrate through polymers to the surface of the steel and cause rust. Water trapped within the steel surface texture can also cause rust under the paint coating. You have all seen rust blisters that form under paint if the steel is not properly sealed.

POR-15 is a Polyurethane that cures by absorbing water molecules from the steel surface and atmosphere. It takes several hours to cure, depending upon the temperature and humidity. The higher the humidity, the faster the cure. The black color is from carbon black filler.

The thicker the applied paint coating, the slower moisture will migrate through the coating. But paint coatings also have limits on how thick they can be applied before the coating will have other problems. Most paints use solvents to thin them for spraying. The solvents must escape during the drying process, so the paint can only be so thick and a drying time between sequential coatings to allow evaporation of the solvent.

POR-15 does not have solvent in it, but the moisture cure process will create micro-bubbles if the coating is applied too thick in one layer because gas molecules are liberated during the cure process which migrate out of the paint during curing, unless it it too thick, which can trap them and allow the formation of micro-bubbles. POR-15 can be applied in multiple thinner coats to prevent the micro-bubbles. Once the coating is fully cured it will be very hard, durable and chemically resistant. Since it is so resistant to chemicals and so smooth on the surface, it is really difficult to apply any other coating over the cured POR-15 and have paint adhere to it. Some might see "fisheyes" or non-wetout areas while painting over the top of the cured polyurethane because there is nothing to cling to because of the slick smooth surface.

Most top coatings will chemically attack previously applied paint because the solvent will absorb into the prior coating and soften it and allow the top coat to gain some adhesion. This does not happen sufficiently to get good adhesion when top coating POR-15, therefore the surface of POR-15 must be mechanically scratched to allow any top coat paint to adhere mechanically by flowing into the surface scratches and locking onto them.

Epoxy primer coatings also need to have their surfaces scratched to allow paint top coats to bond to them if they are allowed to fully cure. Epoxy cures by means of a chemical cross-linking process and they are also very chemically resistant and hard.

All coatings need the steel surface to have some micro-texture to allow the paint to adhere and obtain a mechanical lock to the surface. That is why all paint manufacturers give instructions to process the surface of the steel by sandblasting or sanding to provide the roughness the paint needs to obtain proper bonding to the steel surface. A phosphate metal prep wash will also give a micro roughened surface to promote better adhesion.

The first paint layer applied to the steel, called a base coat or primer coat, depends upon your preference. The two best polymers for the first coat are definitely either epoxy or a moisture cured polyurethane. Each has its advantages and its dis-advantages. Both should be sanded or roughed-up by a scotchbrite pad before applying any other paint over the top of them. A two-part chemically cured polyurethane (not moisture cured) is not as good as epoxy or moisture cured polyurethane for bonding and protecting bare steel.

Take note that even though a paint may be labeled as a "primer" does not mean that it should be the base coat on the steel. Many paints labeled as "primers" are actually meant to be applied over a base coat and used to fill any surface roughness, with multiple sanding and recoating to achieve the desired smoothness prior to applying the final color coat. Many years ago I used "primer" that was a lacquer based paint and the steel rusted under it. This is because most of these "primer" paints are filled with talc and other fillers to make them easy to sand but which allow water molecules to easily migrate through them to the steel below if the steel is not first coated with a proper primer, like epoxy or moisture cured polyurethane.

My choice is a moisture cured polyurethane base coat. This is due to the fact that any water that is still adhered into the micro-texture of the steel will be absorbed and prevent any future rust formation. Epoxy does not do this. It is this absorption of moisture from the steel surface that allows a moisture cured polyurethane to be used directly over slightly rusty steel with excellent results. All rust has some amount of water in its surface structure, which is removed by the curing of the polyurethane and prevents it from continuing to rust after the paint is applied.

Production car painters would choose epoxy as their base coat because it can be cured faster in a heated paint booth. Time is money.

There are several manufactures of moisture cured polyurethanes. The two that I have used are POR-15 and Chassis Saver. Moisture cured polyurethane paints do not resist UV and will be broken down if exposed for long periods of time to the sun. Epoxy will also breakdown but is better at resisting UV radiation.

I use the silver colored Chassis Saver because it has aluminum flakes added instead of carbon black. When the paint is applied, the flakes lay down parallel to the surface of the steel and create a multi-layered flake barrier that is much better at blocking the migration of water molecules through the polyurethane, hence giving it a much better rating in salt water corrosion testing. Water does not migrate through aluminum but does through polymers. Chassis Saver is also much lower cost then POR-15.

If you want to apply a second coat of Chassis Saver, you need to wait until the surface has just gone past its tacky stage and doesn't have any sticky feel. But if you wait too long, you should sand the surface to insure that your second coat will adhere properly. This also applies to epoxy paints. A second coat, or a color paint coat, should be applied over the top of the Chassis Saver before it reaches full cure to avoid sanding. A second coat of Chassis Saver can be applied after about 4 hours. It does not need to cure as long if Chassis Saver is being applied over itself as long as you don't use a solvent to thin it. A solvent thinned color coat is applied about 8-12 hours later. If the color coat is applied before the polyurethane reaches full cure, then the solvent in the paint will attack the surface and allow good adhesion. If you go past 18 hours, then it is best to sand the surface before applying the next coat. Moisture cured polyurethanes can be thinned with polyurethane solvents to make them easier to spray, but not more than about 10% by volume. Just remember to spray a thinner coat if solvent is used to prevent solvent entrapment, and let it cure a little longer before applying another coat over it.

Chassis Saver sands well once cured. I have used it for the sanding primer coats prior to final painting because it flows so smooth. It is more difficult to sand than sanding primers but it sands more easily than epoxy. And I know that if I sand through to bare metal, then the next Chassis Saver coat will properly seal the steel, which won't happen if you sand through sanding primer and repaint with sanding primer over the bare steel. It is much more resistant to rock chips than sanding primers when used under color paint coatings.

I definitely recommend Chassis Saver on the underside of your car. You don't have to apply a top coat over it if it won't be in direct sun light. It can be applied using a brush, paint roller or sprayed. It flows so well that even a brush or roller applied coating will look very smooth when cured. Two coats are recommended for best protection. Be careful not to put it on too thick in the corners and edges or it will show signs of micro-bubbles. If that happens, don't worry about it. If it bubbles badly, you could always sand it down and apply another coating over the affected area.

Don't let the paint can stay open for any longer than necessary. I always apply a layer of food plastic wrap over the open can before putting the lid back on to prevent the lid from becoming "welded" in place from cured paint. I also turn the can upside down to make sure to coat the inside lid sealing surfaces to prevent any moisture from getting inside the can so that I get longer shelf life. Pour out of the can into another container what you will use in an hour's time and then reseal the original can. Your other container can stay open for an hour or more while you dip into it if painting with a brush or roller before it starts to get thick enough to make it harder to apply. Do not pour any paint from your used paint container back into the original paint can. It will cause it to harden in the can because it will have absorbed enough moisture from the air to complete the cure process.

Wear gloves because it is very difficult to remove from your skin if it has been on your skin for more than 10 minutes. It will absorb the moisture from your skin and cure fast. Wash-up with lacquer thinner. Once cured, it will not wash out of anything. It will take two weeks to wear off of your skin before you don't look like the "tin man" anymore if you don't remove it from your skin before it cures. It adheres very well to fabrics and leather, even tire rubber. Ask me how I know!

[Rodney Nelson]

Hi 911-Hotrod,

Thank you for this detailed reply. A majority of what you stated is what I have been discovering during my research and why I was leaning towards using POR-15. I did see that there were other products similar but I was simply trying to wrap my head around why POR-15 had the benefits it does.

My plan was to use POR-15 and then use POR-15 Brands Epoxy primer which is designed to stick to POR-15 without sanding. Then I was going to put monstaliner on top of that. A pretty simple 3 step process.

It sounds like you have tried POR-15 before but you are leaning towards chassis saver. Which is fine by me because it seems to have the same properties.

It seems that most people have issues with POR-15 because they think since they can paint it over rust that they can totally not prep the surface which is wrong. And they think that they can put it on surfaces that are exposed to sunlight, which you can't do. They people that you find that have been using it for years swear by it.

I did screw one thing up that I would like to ask you about. I did use seam sealer directly on to the metal and I would like to use either POR-15 or Chassis Saver ontop of the seam sealer. I knot this is not ideal, but will it be okay? I don't want to take it off in those locations. Or maybe just prime those areas and put the POR-15 or Chassis saver around it...?

Again, thank you for clarifying how POR-15/Chassis Saver works, I think most people don't understand the benefits, compared to standard etch primer.

On the body panels, top side, I will be using a standard process... of etch primer, body filler, high build primer, Sealer, base, and clear coat. I'm leaning towards BASF brand RM, which is the sister product to Glasurit. However, after talking to WESCO paints, multiple people, at multiple locations... I may use swap out Glasurit just for the base, and use RM for the clear to save a bit on cost, but still get the best paint. The price difference is not that much.

Rodney

[911-Hotrod]

Etch primer was designed to be a much faster method of applying paint to bare metal for the automotive body repair industry. It is not as good as epoxy or moisture cured polyurethane, but time is money in the body repair business, and they aren't doing a "forever" collector car either.

I have no knowledge of what POR-15 company may have come up with to apply to their POR-15 moisture cured polyurethane that would require no sanding or surface prep first. If you understand the high chemical resistance of the polyurethane and that most solvents used to thin paints will not effectively attack the polyurethane to allow a top coat paint to properly adhere to the polyurethane, then you would believe as I do that the only proper way to adhere a top coat to the polyurethane would be to give it a textured surface for the top coat paint to adhere to the micro scratches and obtain a mechanical lock to the polyurethane base coat. The same is true for epoxy.

I personally would never apply any paint over the top of either epoxy or moisture cured polyurethane without providing a textured surface first. There maybe some epoxy formulation that POR-15 company has come up with to stick to the very smooth surface of the POR-15 polyurethane, but it will never stick as well as it would if the surface has micro scratches. Unless there is no other way, I would skip applying their epoxy over top of their polyurethane. Just texture the surface and go straight to sanding primer or top coat color.

Chassis Saver has two benefits over POR-15, the aluminum flakes which provide a better barrier to water molecule migration thru the material and the cost is much lower.

Seam sealers are mostly polyurethane formulations. There are two-part types and single part types that cure by moisture or by solvent evaporation. There are also rubberized epoxy formulations. Most seam sealers are flexible once cured. This would make them more difficult to texturize prior to painting over them, but most of them can be directly painted over and still have adequate adhesion.

I have painted with Chassis Saver over the top of rubber tires, rubber moldings and plastic parts such as bumpers, leather and fabric. I have never had it not stick to anything and everything it was painted on, even the overspray.

I repainted an F550 flatbed truck where the steel flatbed had a very thick layer of rust which required an air powered needle chisel scaler to chip it off. The rust came off in thick scales. I then poured on muriatic acid to dissolve as much of the remaining surface rust as possible. I always remove as much of the rust as possible even though I know that thin rust could be painted over by Chassis Saver, but why do an inferior job? I then used phosphoric acid to prep the steel prior to applying Chassis Saver. I then applied an industrial enamel tractor paint before the Chassis Saver reached full cure. It worked out great except some of the over spray from the Chassis Saver floated as much as 8 feet away and landed on the front of the truck's cab where I had not masked off. I had only masked off 4 feet from the area that I was spraying. Even though the cab paint had not been cleaned in years and had lots of dust on the surface, the Chassis Saver stuck so well that it would not come off without being sanded off. I had to color sand and buff the cab paint anyway, so it worked out. Just be aware that moisture cured polyurethane overspray does not flash dry in the air like most paints that settles as dust on other surfaces and wipes away easily. The floating overspray will stick to anything it lands on and will be permanent if it is not removed with solvent before it cures.

I don't see any reason why the moisture cured polyurethane would not adhere well to the seam sealer. I would still recommend that you use a scotchbite pad to take the glossy sheen from off of the seam sealer surface prior to painting over it if you want the best adhesion possible. Moisture cured polyurethanes do have great stick to almost all types of materials, just like glue sticks to most surfaces, but the more surface texture there is, the better the stick. Don't "prime" over the seam sealer prior to applying the moisture cured polyurethane. There is no primer that would stick any better than the polyurethane.

I would recommend using either epoxy or moisture cured polyurethane on any and all metal surface instead of etch primers. They are far superior to any etch primer. If you want the best adhesion, then produce a micro textured surface, then use a phosphoric acid metal prep prior to applying the epoxy or moisture cured polyurethane. Chassis Saver is less expensive than epoxy primer. The phosphoric acid prep produces a microscopic crystalline structure that looks like a forest of trees when viewed with an electron microscope, that provides micro anchors for the paint to attach to. It also gives the surface a pH that is acceptable for the paint chemical compatibility.

All of the paint manufacturers have tech support people that you can call directly because most paint store people are not that good at the chemistry and properties of the paints, some don't even have any actual hands-on experience. Just remember that most people in the paint and body repair business gain their training by having their boss teach them. Who taught the boss? His boss of coarse. This hand-me-down training process passes on many bad ideas and bad procedures. Avoid that by going straight to the technical experts at the paint manufacturers directly. I come from the science and engineering side of things and it is my nature to research, experiment, test, test, and then test some more because I am a perfectionist and want the best possible for my stuff.

Not all paints are created equal. Automotive paints are getting really expensive. I have paid from $50/gallon to almost $400/gallon. It all depends upon your requirements and budget. The best paint I have used is made for the marine luxury yacht market where the paint needs to survive 20+ years of outdoor exposure such as Alexseal. There are lots of choices. I have read that there are some new developments regarding moisture cured polyurethanes that are very UV resistant and can be used on sun exposed surfaces, even as a clear coat. These developments are being prompted because the paint manufactures are trying to get away from solvents to reduce VOC emissions. Do your research.

You are doing a great job. I tell people that anything is possible if you have the right knowledge, tools, materials and desire. You are proof of that statement.

[Trackrash]

This is archival information. Thanks.

[Rodney Nelson]

Hi 911-Hotrod,

Again, thank you for this very informative lesson. And thank you for the compliments. At this point I believe I will use Chassis Saver, and Epoxy Primer, and then what every undercoating I end up going with.

As far as the tech advice from the paint shops, I have actually talked to every WESCO in town because I was trying to get varying ideas. They all seemed to have different expertise and knowledge. So, you are definitely right about talking to technical experts.

Thanks again!

Rodney

[Rodney Nelson]

Hi 911-Hotrod,

I just found out that the same company that makes Chassis Saver also makes Monstaliner. So, I was investigating if I could apply monstaliner directly onto Chassis Saver and this is what I found...

If your bed has minor rusted areas, Monstaliner can be applied directly over rust. Proceed with taping/masking in Step 6. If extensive rust is present, it is advisable to first coat these areas using Magnet Chassis Saver #934 Aluminum Rust Preventive Truck & Auto Underbody Coating. Apply 2 coats of #934 and allow to dry overnight before applying Monstaliner. Contact your dealer or Magnet Paints technical services with rust related questions or for further information.

So, it looks like there really is not a need for a etch primer as I can apply Monstaliner right to Chassis Saver. I did call and talk to their technical team already. But I will call them again and ask if it is advisable to sand 24 hours after last coat of Chassis Saver.

Thanks,

Rodney

[Rodney Nelson]

Ok it has been a while since I posted last but I have definitely been keeping busy.

I decided to do some side projects I will call them. Projects that are easier than the body work and tend to go faster as I can do them in steps here and there as time permits.

I finished up the restoration of the front sway bar assembly. Final coat of POR15, in gloss black with new bushings and bolts from Beltmetric. Can't wait to install it.





Next was the front turn signals. I ended up getting a good deal on these. The wire harnesses were in great shape too. All they needed was a cleaning and rubber silcon oil too keep the rubber grommets nice and soft...

[Rodney Nelson]

After sandblasting...





Some big holes were present...





Time to patch up the holes...

[Rodney Nelson]

Simply used JB Weld... Don't worry nothing structural. It worked great in this application, filling all of the holes.

[Rodney Nelson]

Everything was turning out so well with the fronts I decided might as well take care of the rears too...





Sandblasted...







Primered...

[Rodney Nelson]

Dark grey paint on the back side of the light assemblies...







Ready for Chrome Paint Inside Bulb area...

[Rodney Nelson]

And the finished product...













And... Wire harnesses were all cleaned up, oiled up, and bagged... waiting for final installation in about a year... hopefully.

[Rodney Nelson]

Another project that I need help with... The Blinker Switch and the Wiper Switch. There were all gritty feeling and would barely move. I was able to use electronic cleaner to free up the wiper switch. But the blinker switch I cannot seem to free up. It does seem to switch between the left and right blinker but it is stuck in the forward position which is turning on the brights. I can not pull it back to un-switch it. I even put it in super hot water and my ultra sonic, I used degreaser, electronics cleaner, oil, and even pb blaster.

Unfortunately, it does not seem that I can take it apart as it looks like there are some type of small copper rivets holding everything together. I'm afraid if I even attempt to take it apart, I don't think I will be able to put it back together???

Do you have any suggestions????



Here you can see it is stuck in the forward position, again, I can't pull it back...

[Rodney Nelson]

Alright, back to the body... I need to start working on getting the passenger side rear flare back on the '72.... Before I can do that I need to put the rear tail light section of the flares back on. If you remember I actually had to cut them off to get the rear cross member installed... Well, before I weld them back in I need to repair the rust that is located at the bottom of the tail light bracket. Check out the holes...





Time to make a template....



Here I am starting to form the flange...





Trial fit was pretty spot on...

[Rodney Nelson]

Ok, time to weld everything up...















Final product came out perfect...

[Rodney Nelson]

Ok, I started to move onto the inner wheel well when believe it or not I found another area that needed to be patched... This is the area where the PO used as a mounting point for the engine, instead of two simple holes to fill he torqued them so tight that it caved in this section of the longitudinal. Best way to repair it is just to cut it out and replace the section....











Here you can see inside the longitudinal on the passenger side. If you remember when I was installing the rear cross member I used a long tube and attached a spray nozzle extension to spray frame cavity primer inside. It looks like it did a good job. But while I'm in there I will clean out some of the debris and spray some more...

[Rodney Nelson]

Per normal, it always doesn't as good in the pics due to the reflections. But this came out great. And it doesn't have to be perfect as it will be covered up by undercoating...

[Rodney Nelson]

Alright now it is time to continue cleaning the wheel well, man this has been a lot of work. I've used angle grinders, angle sanders, I bought that long reach grinder, I've used wire brushes... But it is slowly getting done...










Finally, the wheel well was clean enough for metal conditioner. You can see the patch I just did and how it just disappeared when the metal was conditioned and everything becomes a flat grey color... Again I use the Eastwood FastEtch. You keep it wet for about 30 minutes as you continually scrub everything with a maroon scotchbrite pad.

[Rodney Nelson]

The small things can be excited when restoring a car that is taking such a long time...

The fun thing, rotating the rotisserie so the 911 is once again right side up and looks like a car again!!!!







Now the wheel well actually looks like a wheel well. Clean and ready for primer and the flares.