Refinishing the Porsche 928
#31
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Love it! ![thumbup](https://rennlist.com/forums/graemlins/thumbup.gif)
I agree with Bob. There are some tough equipment prerequisites, but achieving very good results by a DIY'er is possible.. which was precisely the motivation for me to begin this topic. Perhaps enough info can be pooled within one topic to serve as a thorough guide for the able hand.
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I agree with Bob. There are some tough equipment prerequisites, but achieving very good results by a DIY'er is possible.. which was precisely the motivation for me to begin this topic. Perhaps enough info can be pooled within one topic to serve as a thorough guide for the able hand.
#32
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https://coloronline.glasurit.com/?language=8
It's been discussed enough already concerning the advantages of using Glasurit products for 928 refinish efforts. The above is a link for Glasurit's online color tools. Additionally, there are smartphone apps available. The tools are meant to be used in conjunction with their mixing systems, but this still provides an invaluable asset to owners that want to chase down particular information with regard to referencing color name, code, standard MYs, and clues about original processes.. single stage, base/clear, solvent, water, pearl coats, undercoat shades, etc..
The first search that should be inputted into the color tools inquiry is the 3 character reference that appears in the lock pillar and shares the label with the color name, not the L code from the options sheet. My Android smartphone app doesn't require me to pre-select a paint system to complete a search, so it searches for mixes across all of them. Searching in 55-line is just as good though, as there are no 928 colors that I am aware of where a 90-line mix exists, but not 55.
Enjoy!
It's been discussed enough already concerning the advantages of using Glasurit products for 928 refinish efforts. The above is a link for Glasurit's online color tools. Additionally, there are smartphone apps available. The tools are meant to be used in conjunction with their mixing systems, but this still provides an invaluable asset to owners that want to chase down particular information with regard to referencing color name, code, standard MYs, and clues about original processes.. single stage, base/clear, solvent, water, pearl coats, undercoat shades, etc..
The first search that should be inputted into the color tools inquiry is the 3 character reference that appears in the lock pillar and shares the label with the color name, not the L code from the options sheet. My Android smartphone app doesn't require me to pre-select a paint system to complete a search, so it searches for mixes across all of them. Searching in 55-line is just as good though, as there are no 928 colors that I am aware of where a 90-line mix exists, but not 55.
Enjoy!
#33
Burning Brakes
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Right. Sometimes it is unavoidable to penetrate original undercoats to make a repair. The idea with the 928 and other cars of comparable quality is that less is more in this sense. There are no improvements to be made by removing the original undercoats. In fact, it is counterintuitive as there is no way (economically) to even match the original quality. And, yes, this is more critical with aluminum as it oxidizes immediately. Even staying inside the 15 minute window from final prep to epoxy won't come close to offer the protection of electrostatic coating, but it's the best we can do when and where necessary.
So assuming no metal damage, how far should one go removing paint on say a single stage paint S4?
Does one simply sand until one sees primer?
#34
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The primer will probably have places that need to be feathered out over the e-coat before new undercoats can be applied. That will depend on how badly the topcoats were broken down. Penetrating the primer is fine.. It's the layer beneath it that we don't want to disturb, if possible.
#35
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if you want a single stage that's going to stand out among other single stage cars, do this:
first coat, 100% single stage color, flash dry
second coat, 100% single stage color
(if you need to color sand, do so here)
third coat, mix 60% single stage color mixed with 40% clear, flash dry
fourth coat, 30% single stage color/70% clear, flash dry
fifth coat, 15% single stage color/85% clear
sand/polish
This creates a depth that single stage urethane normally doesn't have, and yet it won't have quite the plastic look that a clear coat can create.
first coat, 100% single stage color, flash dry
second coat, 100% single stage color
(if you need to color sand, do so here)
third coat, mix 60% single stage color mixed with 40% clear, flash dry
fourth coat, 30% single stage color/70% clear, flash dry
fifth coat, 15% single stage color/85% clear
sand/polish
This creates a depth that single stage urethane normally doesn't have, and yet it won't have quite the plastic look that a clear coat can create.
#36
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if you want a single stage that's going to stand out among other single stage cars, do this:
first coat, 100% single stage color, flash dry
second coat, 100% single stage color
(if you need to color sand, do so here)
third coat, mix 60% single stage color mixed with 40% clear, flash dry
fourth coat, 30% single stage color/70% clear, flash dry
fifth coat, 15% single stage color/85% clear
sand/polish
This creates a depth that single stage urethane normally doesn't have, and yet it won't have quite the plastic look that a clear coat can create.
first coat, 100% single stage color, flash dry
second coat, 100% single stage color
(if you need to color sand, do so here)
third coat, mix 60% single stage color mixed with 40% clear, flash dry
fourth coat, 30% single stage color/70% clear, flash dry
fifth coat, 15% single stage color/85% clear
sand/polish
This creates a depth that single stage urethane normally doesn't have, and yet it won't have quite the plastic look that a clear coat can create.
Using 22-line and any 923 series Glasurit clear to do this comes with a caveat. The bonus is that you end up with a show car finish. The downside is the upkeep of maintaining that it's spotless and rock chips end up looking like craters. Some people want that finish regardless. I grew out of it because I'm not too big on garage queens.
Nevertheless, you outline a process that some will have interest in. I do think going 100% clear for the final coats is one notch 'better'.
#37
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this is some hard core paint nerd talk....i love it.
i did this on a 951. red. you really, honestly couldn't determine where the "top" of the single stage color was.
i didn't want to go with a flat base coat sprayed over with clear. i wanted the pigment suspended...light does go under it and break up the surface.
the problem that i didn't anticipate....it was so smooth/reflective that it picked up way to much color of what was around it and the color of the sky. blue sky doesn't look so cool reflecting off of red paint.
i can't offer any opinions or commentary about glasurit, other than the old stuff on 80's cars color sands well and urethane can adhere to it perfectly....
i used ppg. i think my painting days are over.....i love doing a good paint job but it takes so much time....
i did this on a 951. red. you really, honestly couldn't determine where the "top" of the single stage color was.
i didn't want to go with a flat base coat sprayed over with clear. i wanted the pigment suspended...light does go under it and break up the surface.
the problem that i didn't anticipate....it was so smooth/reflective that it picked up way to much color of what was around it and the color of the sky. blue sky doesn't look so cool reflecting off of red paint.
i can't offer any opinions or commentary about glasurit, other than the old stuff on 80's cars color sands well and urethane can adhere to it perfectly....
i used ppg. i think my painting days are over.....i love doing a good paint job but it takes so much time....
#38
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Comes with passion I suppose. I bet that 951 looked awesome! I don't want to be dominant in these conversations and I really appreciate your contribution to the topic. As I said, a lot of guys/gals want that finish, and that's why your comment adds value. It expands the conversation beyond restoring OE like & kind refinishing.. Something I have probably focused too much on in my career.
PPG, as you well know, has as broad a range of products as any paint maker. Maybe they have the broadest reach actually. For most of their products, the application steps you chose make a lot of sense for max depth. Concept single stage and DCU clears are what come to mind. I might even wager that's what was used on the 951.
My response wasn't a rebuttal. Perhaps it was an asterisk.. All types of application advice is relative. There is little that is universal on the topic of application over the many diverse refinish products available.
That brings me to another point. A phenomenal paint job can be performed using brands besides BASF and Glasurit.
#39
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I apologize for overlooking your question before and I doubt you'll be fully satisfied with my answer. I can't say for sure whether that color was originally applied as single stage, base/clear, or if both application processes were used at different times on different cars.
#40
Chronic Tool Dropper
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You touch on a very important point for cars that are driven, and that's repairability. Even simple common damage like a rock chip demands that you pretty much follow the original steps to rebuild the finish, at least if you want the resulting repair to disappear. For this there's no substitute for a good single stage, followed by a simple base clear. As much as we love the depth of a multi-stage graduated finish, exotic pearls and suspended metallics, doing good repairs on them is a huge challenge even if you know exactly the refinishing process used.
#41
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Wrapping the front bumper cover, mirrors, and sometimes the whole car with products like Xpel, etc., to circumvent stone chips. Problem is now you have chip(s) in the Xpel and sometimes the stone(s) still make there way to the clear coat/paint below. T
#42
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I have a more basic question regarding single stage paints. My GP single stage white car needs repair work (AKA repaint) on the right fender and the urethane nose, the rest of the car has original paint in good shape. Most shops want to shoot a 2 stage job on the car for the repair. For reference, I once had a 911 that had undergone the same repair process I'm suggesting (a 50/50 mix of single and 2 stage) and it never looked right, they aged differently and the sheen was incorrect.
Do I demand a single stage repair or maybe my past experience is clouded by poor workmanship? Keep in mind this is a driver quality/ very original car that sleeps in the garage mostly.
Do I demand a single stage repair or maybe my past experience is clouded by poor workmanship? Keep in mind this is a driver quality/ very original car that sleeps in the garage mostly.
#43
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h20quality,
Good question and I imagine many 928 owners are in a similar predicament where their cars have age, but are well-kept original examples with just a couple issues. Obviously, this isn't too critical for a complete respray.
Fresh 22-line single stage or any other urethane single stage product is probably going to have a noticeable difference in shine. If the shop knows their products, you would probably be best served to let them do the work in base/clear. I would advise that you buff the car to its greatest potential first. This will be the sheen you want them to match and GP White can really wake up with just a little help from a buffer. A prideful painter will know how to manipulate their clear coat to get to an acceptable level of closeness.
As an example, my first effort is to go to faster hardeners as they will kill some shine once the paint is fully cured. My next move is putting in a flex additive as they reduce shine another notch, especially in conjunction with fast hardener. There aren't many more options from there besides going to matte additives. Honestly, if it were bad enough to require any proportion of matte additives, then the whole car needs to be refinished.
Good question and I imagine many 928 owners are in a similar predicament where their cars have age, but are well-kept original examples with just a couple issues. Obviously, this isn't too critical for a complete respray.
Fresh 22-line single stage or any other urethane single stage product is probably going to have a noticeable difference in shine. If the shop knows their products, you would probably be best served to let them do the work in base/clear. I would advise that you buff the car to its greatest potential first. This will be the sheen you want them to match and GP White can really wake up with just a little help from a buffer. A prideful painter will know how to manipulate their clear coat to get to an acceptable level of closeness.
As an example, my first effort is to go to faster hardeners as they will kill some shine once the paint is fully cured. My next move is putting in a flex additive as they reduce shine another notch, especially in conjunction with fast hardener. There aren't many more options from there besides going to matte additives. Honestly, if it were bad enough to require any proportion of matte additives, then the whole car needs to be refinished.
#44
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Here's a pic that demonstrates what I mentioned about the downside of the painting method for single stage that I mentioned above. You can see how much color is reflected from trees, sky, sun, etc. It created pinkish hues and burnt orange hues that I didn't really like. It was killer when the sun was rising, setting, or at night under lights. Unfortunately I couldn't find any pics. BTW, this was a pic from an old Razor flip phone so image quality is junk.....sorry about that