So the last post I asked about Wurth products. General consensus was they are the top of the line. Having said that, I also discovered U-Pol makes the underbody coating for Wurth. There are a LOT of guys spraying the raptor liner under their vehicles. High Dollar builds as well as budget builds. Raptor Liner is tough and is supposed to help spread a point load of several inches of the body, whereas the underbody coatings are rubberized (raptor liner may have some rubber in it) and the onject bounces off rather than spreads the load. What's your alls take on these two specific products....
I have used both. The bed liner is a harder material and is 2k. The Wurth is 1k The Wurth is softer but don’t confuse that as a weakness. The Wurth is a better sound deadener and less fumes. The raptor can be tinted with paint. That’s it’s only advantage Both products are probably equally priced.
The upol is called gravatex plus The Wurth is SKS. I know this one is water based. I have used both. The money is probably the same for both. I would prefer the Wurth. When I used these, I had the expensive gun from Wurth. I haven’t used the Wurth with the standard Shultz style gun (basic undercoating/bed liner gun)
On a side note. I have had issues with all these adhering to urethane seam sealer. I have fixed this by allowing the seam sealer to cure and priming over the seam sealer area. I would epoxy, then seam seal, then spot in epoxy over the seam sealer.
No. It’s nothing like a petroleum based undercoating. It dries hard but has more give or flex than the bed liner
So , is it better to go over bare metal or prime first with say epoxy or etch? I may do the underside of the coupe to protect it from salt. I wanna take it to Bonneville at some point.
Personally I'd epoxy prime all bare metal, and make sure to let it dribble down the gaps and seams. Then I'd use a good topcoat paint over that. Then you are sure all surfaces are covered, even the parts that the thick liner can't soak down into. You could scuff the paint before the liner if you need to.
I should be a sales rep for Raptor. I love this stuff. I spray everything with it. Be careful it does travel. I have some on the front of my building that won’t come off.
I used the WURTH stuff at a couple dealerships and it worked great , it can come off , not as durable I suppose as bed liner . it’s not soft and dirt / dust does not stick . Cars would come in and either be dusty or spotless black and clean . They also make a beige one as well if you want to be fancy . Did the floors in my fleetline beige and the frame and suspension black . I was the only one who saw it but I thought it looked neat .
I'm needing to spray under body my car, from under the body and did not want to wear half of the material ?
Worth and U-pol gravitex are water based, no catalyst. In my opinion, the water based is a better sound deadener compared to bed liner.
Buy disposable coveralls and a face mask . Either that or brush it on , or flip the car on its roof .
I used the raptor liner on the bottom of my cab. I was told it does not like urethane primer, Seam sealer or bondo. To dress the cab and do minor repairs and seam sealing I used JB Weld prior to applying the raptor liner. It turned out nice. I also shot the seat riser and the under seat area. I’d use it again.
Wurth SKS is paintable , if it gets on you or somewhere you dont want it wash with water (before it dires!)
If you paint over the seam sealer first, with either epoxy primer, or that, and a 2k topcoat, it will do just fine over seam sealer. The seam sealer needs to be fully cured, though. I use 2k seam sealer, and leave it for 24-hours. I try to primer and topcoat anywhere that I am applying it. Have not had it knocked off yet, even in a truck bed.
Seam sealers are generally softer than the bed liner. That’s one reason it cracks on seam sealer. I sandwich seam sealer with epoxy primer. I’ve had undercoating , raptor and the water based products have issues with 3m urethane seam sealer.
I find that this is a lot less "squishy" than 1k seam sealers: 3M Heavy-Bodied Seam Sealer, 08308. It is an epoxy-type sealer, instead of their urethane one.
I have seen that done, but am not a fan, as it does not like a whole lot of flex. Nothing that I have used it on has been hit (yet), but I have seen it broken on OEM installations.
If you're looking for a coating system to combat salt corrosion this video should help How to PROPERLY Paint Over Rust Part 2 of 2. Applying paint. (Car Rust Repair) - YouTube
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