Preping fenders before handing them off to body shop

[markjhatch]

I am going to put on new front fenders as well as rear quarters on my 69. Obviously the body shop will have to weld on the rear quarters.

Should I paint the *inside* of these fenders with something like POR or leave it to the body shop to prep it. Given the expense of this level of restoration, I dont want to do it again... I have had good luck with POR on suspension and other areas that don't show. But I am not sure it is the best for something like this and also a little worried that it might impact the weldability of the rear quarters.

Any experience or advice here?

Thanks

Mark

[tjp]

If I can add to this inquiry without hijacking it....

For the same reasons (dont want to have to do it again) I have done both the inside and outside of my "new" front fenders with POR15. The inside is the inside and will be fine and not need to be painted.

As for the outside, is there a primer product that will stick to the POR15 as it is, or will the POR 15 need to be given some tooth for the primer to adhere?

Sorry if this is a hijack.

Tim

[notoptoy]

I would instruct them that you want the fenders painted on the inside. I would not paint them first as yes, they will want clean metal to work with.
The body shop that did my Impala used an undercoat-like material that was textured, it didn't require (recommend) a top coat like POR15, which will fade over time with exposure to light - even a little light. I've been very happy with it and it sheds rocks and dirt with ease - it's sort of like a spray on bedliner but thinner and lighter.

[notoptoy]

If I can add to this inquiry without hijacking it....

For the same reasons (dont want to have to do it again) I have done both the inside and outside of my "new" front fenders with POR15. The inside is the inside and will be fine and not need to be painted.

As for the outside, is there a primer product that will stick to the POR15 as it is, or will the POR 15 need to be given some tooth for the primer to adhere?

Sorry if this is a hijack.

Tim

POR15 is very picky about compatible materials, and they make their own recommended primers and top coats for the POR15 product. I think I would stick with their "System" if you have already applied the product for best results.

[tjp]

[/quote]...they make their own recommended primers and top coats for the POR15 product. I think I would stick with their "System" if you have already applied the product for best results.[/quote]

I must be blind. Big Time. As I didn't see this on their web site. But then again, I have never been able to place an order on their web site either. They always fail. I have taken to ordering the actually POR15 from Eastwood as it is the same price as the por15 web site and I get free shipping from eastwood but not the other.

Thanks!

[notoptoy]

The (rather detailed) instructions for the POR 15 has all the recommendations and product compatibility - stuff like how important relative humidity is to the curing process, exposure to light etc.
I also went through Eastwood.
From POR's website:
Prep prodcuts: http://www.por15.com/Preparation-Products/products/2/" onclick="window.open(this.href);return false;
Primers: http://www.por15.com/Primers/products/3/" onclick="window.open(this.href);return false;
Top coats: http://www.por15.com/Single-Part-Topcoats/products/4/" onclick="window.open(this.href);return false;

Etc., etc., etc.

[pebbles]

I am going to put on new front fenders as well as rear quarters on my 69. Obviously the body shop will have to weld on the rear quarters.

Should I paint the *inside* of these fenders with something like POR or leave it to the body shop to prep it. Given the expense of this level of restoration, I dont want to do it again... I have had good luck with POR on suspension and other areas that don't show. But I am not sure it is the best for something like this and also a little worried that it might impact the weldability of the rear quarters.

Any experience or advice here?

Thanks

Mark

POR likes rust, or sandblasted surfaces. the roadster body panels would be better suited with a sanding and primer/painting. A heavy handed maroon scotchbrite (by hand or ocsillating sander)and a 2 part primer would be good. .02

[Linda]

Can you define a "2 part primer"?
Thanks
Linda

[pebbles]

Um, probably not very well. A catylist type. There are so many out there now, epoxy, polyester, self etching, etc, one that you add an activator to. Check with the body shop to ensure the primer is compatible with their "system". I am still in the experimental stage with the roadster,,some materials are adhering, and some aren't
A catalyzed primer will resist moisture far better/longer then a non cat.

[MSmethers]

Mark, I would not pre paint them. If you want the undersides to look good upon completion, the body shop will have to mask the inside of the fender prior to application of primer (At least 2x's) and again prior to Basecoat/Clearcoat, not to mention the compounds etc from the "cut and buff". Masking is time consuming and subsequently, money consuming. Will the bodyshop be assembling the car after paint? If not, a maroon scotch brite (with a heavy hand) and a quality (if there is such a thing) rattlecan bed liner has served me well. If it were mine (and what I'm doing on my own) after paint/cut/buff, mask off the exterior, scotchbrite and spray. Alternatively have the bodyshop paint the in/undersides in BC/CC. Then again, money consuming. POR 15 has no UV protection and must be topcoated. I'm unfamiliar with the rockchip resistance of POR 15 products.

Linda, in my limited knowledge of all things primer, a 2 part primer (aka 2K primers) come in two parts. The resins and other parts that make up the primer and a catalyst to induce the chemical reaction to harden/dry. Plastic body fillers will actually get warm to the touch as this reaction occurs. Primers mainly come either as a polyester primer/filler (sprayable bondo), 2K primer/filler, etching primer, and Epoxy primer. The epoxies make a great base over bare metal as it seals out all moisture preventing further corrosion/oxidization, but have no build/fill/level characteritics. The polyester's and 2K don't offer much in the way of moisture protection but fill imperfections/flatten panels well.

Hope this helps clarify a little.

Marshal

[pebbles]

Marshal, what are your thoughts on the red stuff, and the green stuff on "new" panels?
I have always removed it prior to using my paint system. I'm Not sure what the Datsun NOS primer is. Alkyd? Waterbased? Alot of it flakes off easily.


Mark, It would depend on what type of final finish you want to achieve. Shiny paint or undercoat. Shiny paint in the trunk? Undercoat the front fenders? Undercoat helps reduce rock dents from tread flings. There are some clear chip guards as well if body color in the wheel wells is preferred.

[markjhatch]

Thanks for all the ideas here. My main goal is rust prevention from the back sides of the fender/inside of rear quarters eating through and ruining the paint job. I wouldn't consider painting the outside of the fenders because of compatibility with the body shop system (also POR has a poor finish, at least in my experience).

I understand that por uv sensitive, but is that an issue for the inside of the fenders (the part that faces the tires or are in the trunk)?

[MSmethers]

Marshal, what are your thoughts on the red stuff, and the green stuff on "new" panels?
I have always removed it prior to using my paint system. I'm Not sure what the Datsun NOS primer is. Alkyd? Waterbased? Alot of it flakes off easily.

I'm not familiar with Datsun's NOS primer. My guess would be Alkyd. All the new panels I've gotten with the black edp primer on them, I've ran the DA over. A few the adhesion was poor, so I stripped them down to metal. If adhesion is good, give it some good "tooth" with 80 grit on the DA and Epoxy prime.

[notoptoy]

MArkJhatch -
The POR will fade, even with minimal exposure to sunlight. The frame (underside of the car, limited exposure to light) on my Impala is starting to fade after 3 years, and it spends 95% of the time in the garage. I do now wish I would have put a top coat on it. My thinking at the time was just like yours, it's concealed, it won't see enough sunlight to fade.
Granted it's not gray, but it is a "milky" or hazy black. A buddy of mine has had the same experience. No seeming degradation of the paint or surface just a subtle shift in the color.

[zippy67roadster]

KBS has a product similar to POR 15 but is self leveling and easy to use. It isn't as picky as to what condition the metal has to be in. I would let the shop spray the fenders then tape off the edges and brush the inside with the KBS product. It looks like it was sprayed on or powder coated when done. It does recommend their top coat to make it more resistant to fading and chips.