Factory Undercoating

[jeff_h]

Searched but didn’t find exactly the topic or comments I wanted.

Working on a ’81 911SC, I want to freshen up the underside and wheel wells before I get into the monuments task of body working and paint.

Assuming proper cleaning/prep and scuff, can a thin fresh layer of SKS be applied over factory undercoating? Just want a black finish, no intention to paint. I have spent significant time under the car and is in excellent condition, which is why I am considering any option than disturbing the factory coating. I understand was applied in best environment possible over the galvanized surface.

If I do come across any suspect areas, I would ensure to strip and prep down to metal, and coat with 2 part epoxy.

Thanks!

[kevin930t]

Yes u can,obvious you want the surface to be degreased anf clean,then what i would do is tun a scotch bright pad over the surface that you are going to coat&also mask off all the areas that you dont want the sks to get on,suspension ect.There are a couple different kinds of sks 1 is waterbaced the other takes a hardener.Good luck

Sent from my SM-N910T using Tapatalk

[jeff_h]

Awesome, thank you. I definitely want to make sure I use correct products on this car - my keeper build.

Suggestions in product (Wurth) to use in this case? Known compatibility issues with factory undercoating?

Or is this just a waste of product and I should just paint to freshen up the aesthetics?

[kevin930t]

Wurths sks 2 part witch is the product itself with a added hardener is what the factory used and like u daid there is not alot of info out there,but thats what i have been using.When u purchase the product it used to come with its own gun,u might want to ask about that. This is what the gun looks like it screws into the bottle.

Sent from my SM-N910T using Tapatalk

[Dpmulvan]

Its called a Schutz gun you can pick one up on eBay for $20, if I remember correctly about 60psi is good. You can't purchase the factory undercoating anymore but upol makes a good substitute and I think they make product for Wurth as well.

[78-911SC]

Check out some of 962porsche posts. Has covered extensively. Upol is who makes the product for Wurths. Amazon sell it in kit form with the gun and comes in colors or I believe you can tint it.

[kevin930t]

U pol,is a cheap substitute.

Sent from my SM-N910T using Tapatalk

[78-911SC]

Kevin never have used the product but I have read many of 962porsche posts on the subject. He is probably the for most expert on this site for anything to do with paint and bodywork. He has restored many Porsches personal and for clients. Just trying to help Jeff with a answer to his question. 962porsche has many post on that subject of undercoating. I have never seen any post stating that it's a cheap substitute. But as I stated I have never used the product and I'm not a expert on the subject. This quote is for fuel tanks which I believe is the same as undercoating but different color.

Originally Posted by 962porsche

I have stated this many times . wurth does not make there own products other manufacturers make it and then it's packaged with a wurth product label .
in this case UPOL is the maker but it is not a match to the color gray Porsche uses on there fuel tanks .
the color gray Porsche uses is tinted and mixed for Porsche exclusively .
the difference from the UPOL / WURTH SKS is there is no blue in the gray as there is with the Porsche mix .

[jeff_h]

Thanks for everyone responding, I do appreciate it. I don't want to start another generic undercoating product thread. I suppose where I wanted this to go was wether it was crazy to just coat over existing rock guard with fresh stuff - rather than the monotonous task of scraping and removing it all. Like I said, the existing factory coating is such great shape and I feel the bottom half of my car could just use simple a refresher before I tackle re-paint.
I want a black finish, figure I would have better long term appearance than painting and potential white (original color) showing up if it chips.

Have been reading through 962porsche posts and finding great information. I am slowly getting used to this new forum....spent near 10 years on VW air-cooled forums and read about everything I could over that period.

[jeff_h]

Just wanted to add onto this for clarification in terminology.
I understand that the Highbuild/Shutz/SKS is used on bottom of the tub, but not used on lower rolled edge of the body rocker is it? This is a harder, less rubberized coating - specifically rock guard?

Been reading about the U-pol gravitex product, is this actually used in all areas? (Trunk, engine bay??)

[962porsche]

Originally Posted by kevin930t

U pol,is a cheap substitute.

Sent from my SM-N910T using Tapatalk

LMFAO

a cheap substitute for what ? wurth ????
are you one of the damb a$$es that think wurth makes any of there own products ????
lets hope your not that dam dumb !
wurth is nothing more the a CO that buys other peoples products and has them packaged in the wurth label .

is it a cheap substitute for the OE 3M stone/chip guard ?
NO i would not say it is just different . you can't buy the same solvent stone guard of days past . you can't even buy the proper color of the old OE 3M stone/chip guard .
if your looking to match the OE color you have to tint a stone guard product to match it .
with the wurth aka u-pol you can tint it to match and the wurth aka u-pol the texture is also the same as the old OE 3M . seams like a win win to me .
you could spray any color chip guard but then it's not a proper match .
you could then paint over the any color chip guard and years down the road you will have the paint being sandblasted off by your tires kicking up road crap . then you will see the wrong color under the paint .

when someone posts a comment like this they really have no idea at all what they are really talking about .
they do not know products nor how to use them !

as for the gun you use . the one posted is one of the cheapest ones and not really worth to much . they are ok for home use but not one you would pick to match proper textures of stone guards .
side note i love how the only color is black on it you know that person have never sprayed any other color but black thru it !
so i guess he is right the 2 part is the way to go . i bet he also thinks bed line makes for a real good stone guard too !

what makes bed liner and a lot of two part chip guards not as good a single part chip guards is there are harder . you may think harder is better but this thinking is wrong .
a hard product is easier to sandblast then a soft material . think of a stone / chip guard as rubber . if you ever tried to sand blast a piece of rubber you would know you would be there for ever trying to sand blast a hole thru it . why ?
thats simple the sand is bouncing off and having little to no effect removing material .
this is not the case with a harder product . sandblasting will eat right into it and over time will blast right thru it to your substrate .

there is a reason why even your 1970's 911 stone guard is a PITA to remove .
over the winter i stripped the bed liner a guy had some one spray on his old 69 mustang . it came right off with a air scraper took less then a day to remove every bit of it .
he had the done 6 years ago and the bed liner was flaking and getting sand blasted off from the wheel houses .

[jeff_h]

Thanks very much for the comments and support. I have moved from a cosmetic restoration, to stripping down to steel and fresh epoxy. I sourced U-Pol Gravitex locally as well as the gun and will get this done by end of summer.
To confirm, I would use the same product from bottom of floor pan up around to the curved rocker portion? (Following existing tape line of course). As well as lower portion inside trunk area?

[962porsche]

that's just what you do !

[nathanbs]

Originally Posted by 962porsche

LMFAO

a cheap substitute for what ? wurth ????
are you one of the damb a$$es that think wurth makes any of there own products ????
lets hope your not that dam dumb !
wurth is nothing more the a CO that buys other peoples products and has them packaged in the wurth label .

is it a cheap substitute for the OE 3M stone/chip guard ?
NO i would not say it is just different . you can't buy the same solvent stone guard of days past . you can't even buy the proper color of the old OE 3M stone/chip guard .
if your looking to match the OE color you have to tint a stone guard product to match it .
with the wurth aka u-pol you can tint it to match and the wurth aka u-pol the texture is also the same as the old OE 3M . seams like a win win to me .
you could spray any color chip guard but then it's not a proper match .
you could then paint over the any color chip guard and years down the road you will have the paint being sandblasted off by your tires kicking up road crap . then you will see the wrong color under the paint .

when someone posts a comment like this they really have no idea at all what they are really talking about .
they do not know products nor how to use them !

as for the gun you use . the one posted is one of the cheapest ones and not really worth to much . they are ok for home use but not one you would pick to match proper textures of stone guards .
side note i love how the only color is black on it you know that person have never sprayed any other color but black thru it !
so i guess he is right the 2 part is the way to go . i bet he also thinks bed line makes for a real good stone guard too !

what makes bed liner and a lot of two part chip guards not as good a single part chip guards is there are harder . you may think harder is better but this thinking is wrong .
a hard product is easier to sandblast then a soft material . think of a stone / chip guard as rubber . if you ever tried to sand blast a piece of rubber you would know you would be there for ever trying to sand blast a hole thru it . why ?
thats simple the sand is bouncing off and having little to no effect removing material .
this is not the case with a harder product . sandblasting will eat right into it and over time will blast right thru it to your substrate .

there is a reason why even your 1970's 911 stone guard is a PITA to remove .
over the winter i stripped the bed liner a guy had some one spray on his old 69 mustang . it came right off with a air scraper took less then a day to remove every bit of it .
he had the done 6 years ago and the bed liner was flaking and getting sand blasted off from the wheel houses .

What do you recommend to use to tint it?

[962porsche]

we get the white u-pol and use good old acrylic enamel .
the enamel give the u-pol the same match with the gloss as the old 3M chip guards also .
you can use lacquer but it tends to dry with not enough of a gloss

[jeff_h]

One last thing to confirm! I assume just a clean, scuffed epoxy surface is fine for applying the chip guard?

[962porsche]

yes a good red scuff padding wipe it down so it's clean and spray your chip guard .

[laire]

i have used u-pol a few times to completely undercoat everything under the car right out to the bottom of the wheel opening . mask off a line between your wheel opening and your outside panel. I sprayed a tintable with the color of the car ,when you go to the paint store to order ask them to leave out the binder, according to my paint supply they claim this will help the color not morph , unmask before it gets hard a pint of color will do a four quart kit