Can you undercoat over undercoating??

[bull]

There are going to be some spots on my car where the undercoating has fallen off (or been beaten, scraped and pried off) during the bodywork process. Can you just spray new undercoating right over some of the old stuff while filling in the blanks or do I need to spray just the metal? I know little to nothing about undercoating other than it's hard to get off. The green spots below show one of the places where it's come off my car.

[Drop Top]

As long as its clean, yes you can. Just make sure that all of the old that is loose is off before you do it. You don't want to do it twice.

[Aussiemadonmopars]

Hey Bull, why don't you do what I did and scrape it all off and start again. It worked out well because I found a few rust spots I wasn't aware of. The process for removal is very easy if you have the right tools & equipment.

[bull]

Hey Bull, why don't you do what I did and scrape it all off and start again. It worked out well because I found a few rust spots I wasn't aware of. The process for removal is very easy if you have the right tools & equipment.

That's an option that I've considered but can't say I'm too interested in. It opens a whole other can 'o worms that is probably best kept sealed. Also there seems to be a lot of debate on what the right tools and equipment are for that job. I've heard everything from heat and a puddy knife to dry ice and a hammer. I may do it someday but for know I'm focused on the parts I can see from a standing position.

[ck1]

I just went over the whole enter under my car with a wire bush just to knock off the loose stuff then use some cheaper rust encapsulate on the rusty spots, "It was when I first started out and wish I would have used better stuff like por-15", and then blue paint and then went over with undercoating, last time I was under the car still looked like it was holding ok........

[bull]

I just went over the whole enter under my car with a wire bush just to knock off the loose stuff then use some cheaper rust encapsulate on the rusty spots, "It was when I first started out and wish I would have used better stuff like por-15", and then blue paint and then went over with undercoating, last time I was under the car still looked like it was holding ok........

Blue paint? You mean body color or is that some kind of sealer?

[Aussiemadonmopars]

Yeah Bull, I went over it with a heat gun and a putty knife, came off really easy and used a kerosene rag to wipe off the smaller bits while it was still hot. Once you get the bulk of it off, the sand blaster can get the rest. Is the car in pieces or is it still on the road? While the car is in pieces or being pulled to pieces it's easy.

[ck1]

I just went over the whole enter under my car with a wire bush just to knock off the loose stuff then use some cheaper rust encapsulate on the rusty spots, "It was when I first started out and wish I would have used better stuff like por-15", and then blue paint and then went over with undercoating, last time I was under the car still looked like it was holding ok........

Blue paint? You mean body color or is that some kind of sealer?

just blue paint.........it wasn't a match to the car but it was blue paint and my car is blue. the stuff i used on the surface rusted areas was called extend and it said that a top coat of paint should be applied over it and then i undercoated over that, it was nothing special just a can of dark blue spay paint from the auto store I wasn't going to be picky underneath my car for I was just gonna under coat it anyway..........

[BigBlockSam]

scrape it all off . if some of it is kinda loose it will hold moister behind it.