Correct colour for underseal

[Cluskera]

Hi, for an 83 SC which is paint code 811 - Kiln Red, what would have been the colour code for the underseal? Was the exact same colour used as on the body? Sometimes the undersides look a slightly different shade ... could be wrong.

I have restored part of the inner wing so want to feather in the correct colour as best I can.

Thanks

[drcoastline]

The underseal (Wurth SKS) would be a taupe/beige color then top coated with 811 Kiln Red. I don't believe the SKS has a color code. The color of the SKS would be beige/taupe like your gas tank.

As I said in your post on the tech board the paint in the wheel wells was a few quick passes of the spray gun, not carefully applied full coats of paint like the body. That would cause variation in the color. In addition the under body of your car has seen 33 years of road debris and lack of attention that have attacked the paint in those areas so it has worn away and faded.

Attached is a photo of the rear wheel well of an original 1974 911S, you can see the original SKS showing through the yellow paint. The next question you need to ask yourself is are you trying to replicate the wheel well as it came from the factory in 1983 or as it looks today after 33 years of use?

[Cluskera]

Mmmm yes, thanks for this. I'm not trying to win awards certainly and yes I can see where the colour had paled on mine.

The car itself has had a colour change but I'm going to one day put it back to 811 so want to pay homage to existing underseal.

I'll take on board what you have outlined and will simply go original 811 and feather it in without re painting the whole inner wing.

[frankc]

I have a similar question on what type & color paint was used for the undercarriage, etc on silver metallic cars (paint code 936-9-3). I removed some surface rust on the rear tunnel panel and then covered the metal with grey POR15 (photo is prior to POR15 application). I now would like to topcoat the POR15 with something that is similar to what the factory used, in terms of color and gloss.

As you can see from the photo in the areas around the tunnel, the factory paint appears to be some type of semi-gloss very light grey. This same paint is used on the bottom of the floor pan and trunk areas. Is this some type of base coat that the factory used over the SKS? Is there a standard paint code that was used in these areas that corresponds the the silver paint code?

I'm not looking for an exact match here, I just don't want the repaired area to stick out like it does now with the glossy dark grey POR15 on it.

Thanks for any suggestions.

[Cluskera]

I'd help if I could - I've since bought a canister of the original factory paint and will just use this after stone chip . Difficult to tell from picture. You could go grey stonechip so it deliberately stands out.

You're going to struggle to match it although auto stores have loads of possible colours.

I always understood the intention was body colour for underside in general. I think there is some variation in certain years .

[drcoastline]

Hi Frankc,

Can you post the photo? Scratch that. For what ever reason the photo didn't come up the first time. I am not exactly sure of which spot you are talking about. But, you have several options. 1. spray on some gray chip guard to cover. 2. get a rattle can of paint that closely matches the chip guard color or your body color. 3. Do nothing. Most of that area is going to be hidden one you put your engine and transmission back in. It all is going to depend on the level of accuracy and correctness you want.

[frankc]

Thanks for the responses. The area I'm referring to is the panel at the rear of the tunnel where all the various cables and harnesses exit. In my photo you can see that the panel is bare metal after I media blasted it.

This panel was mostly painted black from the factory, then covered with a black tar-like under-coat that became very hard after all these years. I would prefer to paint this panel the lighter undercarriage color as the black makes it difficult to easily spot any rust that begins to form in this area. In fact, I was unaware of the surface rust until I dropped the engine/transmission and started removing the under-coating.

It seems this panel may not have been galvanized like the rest of the chassis because the body panels adjacent to it had no rust at all, even in places where the chip guard had been damaged (amazingly still shiny zinc). Later today I'll post a picture of the panel before media blasting so you can see the condition before.

You can also see from the photo that the factory was not very thorough in painting this section of the chassis. Note that the area behind the torsion tube is still primer grey, as is the bottom of the torsion tube, where the trailing arms attach, etc. I realize that the painting of these areas was really a "best effort", but I was wondering if this level of coverage is consistent with other cars of this era (mid-year).

[drcoastline]

The painting is pretty consistent for the era. That area would be mostly over spray from the factory. If your chip guard is black someone has been in there. From the factory the Wurth Shutz (chip guard) would be a taupe/grey color like the car above. If you don't want to reapply the chi guard hit it with a gray spray paint but not primer as that will attract/hold water causing rust.

Oh yeah, and you are correct in 1977 only part of the car was galvanized.

[frankc]

drcoastline,

So are you suggesting that the light grey you see in this area is not actually paint, but the natural color of the Wurth SKS itself (i.e.; this area was not painted)?

When cleaning the bottom of the floor pan, I noticed that if I was too aggressive that the light grey color on the high points would wear away, revealing an orangy-brown color underneath, which I thought was the SKS under a thin layer of paint. Does this sound right?

[frankc]

Regarding the galvanizing, I have read in several places that in '76 they galvanized all but the roofs (coupes), and starting in '77 is when 100% of the chassis was galvanized. But who knows, this particular panel may have come pre-assembled with the entire tunnel assembly (not galvanized), and then welded in, which would explain things. You can see what appears to be the brass brazing of the tubes where they pass through the panel.

[drcoastline]

Originally Posted by frankc

drcoastline,

So are you suggesting that the light grey you see in this area is not actually paint, but the natural color of the Wurth SKS itself (i.e.; this area was not painted)?

When cleaning the bottom of the floor pan, I noticed that if I was too aggressive that the light grey color on the high points would wear away, revealing an orangy-brown color underneath, which I thought was the SKS under a thin layer of paint. Does this sound right?

Yes, the SKS is a beige/taupe/grey color from the factory. Like the wheel well of the car above. The SKS was applied directly to the steel panels. Including the engine bay. When the car is painted they would apply a few quick passes in the engine compartment and wheel wells. The area you are speaking about would have been SKS with maybe some over spray. For the most part the area you are working on should look very much like the bottom of the floor pan. Unfinished SKS.

[frankc]

Originally Posted by drcoastline

Yes, the SKS is a beige/taupe/grey color from the factory. Like the wheel well of the car above. The SKS was applied directly to the steel panels. Including the engine bay. When the car is painted they would apply a few quick passes in the engine compartment and wheel wells. The area you are speaking about would have been SKS with maybe some over spray. For the most part the area you are working on should look very much like the bottom of the floor pan. Unfinished SKS.

Thanks - I was beginning to suspect that upon closer examination of the coated/uncoated areas under the chassis.

So would the "Beige" SKS that I can purchase today be a close match for what is on my car (accounting for aging)? I always thought the Beige SKS is what was applied to the gas tank, which appears to be a slightly darker grey. Do you know if the same SKS was applied to both the chassis bottom and gas tank? Or, perhaps was the gas tank painted after the SKS application?

Thanks again for all your help. I'll have to place an order for the Beige SKS, since I doubt I'll be able to find it locally.

[drcoastline]

The SKS formula changed a few years back. To the best of my knowledge you can no longer get the original petroleum based beige formula unless, you find someone with a stock pile or a jobber that has some on a shelf they forgot about. The new formula is water based and I do not believe it comes in the beige. Grey is as close as you are going to get off the shelf as far as I know. So that's the long way of saying no unless you get lucky and find some.

I believe the original tank and underbody SKS are the same product and color.

Porsche962 on here has given some great advice regarding this subject in the past. He has switched from Wurth SKS to U-pol Gravitex. The U-pol product is still petroleum based. He uses the Gravitex to get the coating and texture desired. When the Gravitex flashes he the top coats with paint that is tinted to replicate the Wurth SKS beige. I am not that concerned with 100% originality so on my targa I will be using the U-pol in grey but will not be painting it. So long as the color is uniform I am ok with that.

FYI- I just read the Wurth stone guard thread below yours. Porsche962 posted in 2010 that 3M makes a beige stone guard. You may want research that. Correction #2 I see it was you that posted.

[frankc]

I saw several mentions that the beige SKS is no longer available, but it still listed on the Wurth USA site:

https://shoponline.wurthusa.com/wurthusa/servlet/CyberVendor/category/G4228734/catalog/group.jsp/

Perhaps the website is just out of date. I also saw some posts about 3M having a similar product available in either grey or beige - which of these two products they are referring to?:

3M Rocker Panel Coating, 23 ounce, Grey, 08889
3M Rocker Panel Coating, 23 ounce Net Wt / 600g, Grey, 08889

3M Rocker Schutz Beige - 08874
3M Rocker Schutz Coating 08874


It seems the "3M Rocker Shutz" would be a good match for the Wurth beige, and maybe the "3M Rocker Panel Coating" for the gas tank, although I can't tell if the latter needs to be top coated.

[frankc]

I mentioned I would post a photo of the rear tunnel panel before I media blasted it. You can see some of the the original black paint still on the panel.

I'm curious why the factory skipped this panel when applying SKS to this area of the chassis. I doubt they would have already run the cable/harness/fuel lines, etc. at that point, so they would have had good access for applying.

[962porsche]

the OE chip guard used on Porsche's was 3M's beige schutz .
the reason as to why it was not sprayed in some areas was it simply not needed in those areas .
it's for chip protection from stones sand and gravel hitting the chassis .
stones will not get to the areas you stated .

wurth no longer offers a beige chip guard as the co. that was selling it to wurth no longer offers it to wurth . as I have said many times in the past wurth does not make there own products they just buy other CO;s products and it's labeled with the wurth name .

as for the body color that you will find on the chip guard .
Porsche does not spray any color on the chip guard it's self what you see for color over the chip guard is nothing more then over spray that ends up there from painting the outer body panels .
when the cars would leave the factory you would see inconsistency's in the coverage of the body color over the chip guard on each car .
there for no two cars would have the same amount of over spray on the chip guard .
if you need to copy the black chassis coating your best match to copy that is SEM rust shield flat black mixed the hardener making the colors gloss a semi gloss black .

08874 3M you can buy from autobodytoolmark.com
they will also have the spray gun for it I how ever do not like the 3M gun . finding one with a adjustable spray nozzle that way it will be much easier to match the texture of what Porsche has .

to match the way the color has landed on the chip guard when your repainting the car you would have to paint the cars the way Porsche did to have the over spray land on the areas where it did .
to do that you would need the stand offs that kept the panels on and with the cars as the car was going thru it's painting proses .
when the cars were painted the bolt on panels were not sitting on the car as they are when the car is all together it is because of this as to why and how the over spray looks o the under side of the panels .

[Cluskera]

Were the bumpers and wings off at the time when it was done...must've been or

It must've been overspray in USA only as my uk car has barely any missed areas.

[962porsche]

the bumpers are not painted on the car .
the fenders , hood and engine lid were set as they would be on the car but they use stand off's that move them away from the car a little to be able to get paint down in side the edges .
right and left hand drive cars are all built and painted in the same way so were the car was getting shipped to makes no difference at all .
you will see when you remove some of the bolt on panels were there is bare metal

you will see when you look at the car real good places like on the back side of hinges the color will not have the same coverage as it does on other parts of the hinge .

the cars are painted as a shell nothing else is on the cars at the time of painting .
things like colored bumpers , mirrors , run down a hole other paint line then the car does .
from time to time if you look hard you may see a little color difference of the main body and the other parts like that .
how ever unlike cars like Toyota , Honda you will never see a big color difference like they have .

how we used to do the cars when restoring them is paint the hole main body with all bolt on panels off the car were we wanted the little bite of over spray on the chip guard we would use a mini gun for that just dusting the color over the areas .
Porsche did not put color over the chip guard per se for a couple of reasons .
the 1st is it will chip off in no time .
2nd cost of material for every car they spray the chassis you can almost paint a hole other car . this is also way you see spots you would think there should be chip guard on .
if a stone will not chip it there is no need to put chip guard there .

as for the color of the chip guard it is beige because Porsche used the 3M solvent base schutz at that time you may no longer be able to buy it in your area in solvent .
I tried the wurth a hand full of times and it was always to light colored of a beige .
on the other hand all the porsches I have had in the shop at the same time with the oe chip guard on the car no two were a match in the shade of beige .
but the color should still be close to the OE color you see .

[frankc]

962porsche,

Thank you very much for all that very useful information.

I did notice when I removed my fenders that there was no paint at the flanges where the fender and chassis were bolted together, surprisingly mostly just bare metal. Which meant when the body putty failed, this area is a prime spot for rust, even on galvanized cars. In fact it was the only spot I found any significant rust on my chassis. I understand why the cars were painted that way (fenders on), but you think that with the experience the factory had by 1977 with the cars already on the road, plus their efforts to reduce corrosion by galvanizing the entire chassis, that they would have provided better rust protection to the top fender/chassis flange area.

I will place an order for the 3M 08874 and give it try in some of the areas I need to repair. Btw, have you noticed any difference in the chip guard color between the chassis and gas tank on the same vehicle?

Thanks

[962porsche]

around the time that Porsche started galvanizing the bodies of there cars so were many other auto makers .
Porsche was just following suit as to what was new to the market .
so it was not like they were or are to concerned with the cars rusting out .
you do know they are designed to last 10 years . if they make the cars last to long you would not need to buy a new one !
the galvanized coating used is so thin it does not really do much . they only make the car last 2 years longer on average .
this always brings up the debate about galvanizing . I will not get into that !
the chassis will on average rot in the same spots as the non galvanized cars do .
as soon as you sand the panel and you hit bare steel you have most likely also removed the galvanized coating too .
the galvanizing is more for between the seams were you can not get top coating then it is for under you top coat and adding protection there .
this is why you would always want to use a weld primer between seams .
when you are down to a bare metal the E-primers replaces the galvanized coating on the outer part of the panels along with adding better adhesion to the bare metal for a filler primer to have some thing to bite into .

it's the same for the finishes on cars Porsche like bmw and benz went from lacquer to urethane enamel . being one of the 1st auto makers to do so most auto makers around that time went from lacquer to enamel then to urethane . Porsche worked with NASF to step right over the straight enamel to a urethane based enamel .
because BMW and Benz are also BASF coating users they did the same thing at the same time .


the fuel tanks have there own special color .
there is no chip guard the color you will need to match the fuel tanks .
we did come up with a exact match to the color and gloss of the fuel tanks by tinting the chip guard .
I will not share the formula .
so if you have to refinish the fuel tank you will have to chip guard it and then paint it to the right color and gloss or spend the time and money tinting the chip guard your self .
that is one of the things that made our resto's just a little better then some of the other shops out there .