Rattle can undercoat, use it or not.

What are your thoughts on using a high quality (3M) undercoat on the inside of a sandblasted body. I'm thinking about applying this to all interior sections that will eventually be covered when interior is done. It is common to find this stuff applied inside doors, why not the whole vehicle? Will this give rust protection & sound deadening?

 

paint it first then undercoat, done it many times, works decent especially for the cost.

 

One thing to consider is that the coating can be a real bitch in the future should the need arise to make a modification-repair.

Think about trying to cut or weld on a panel coated with that stuff on the backside.

Especially in any area where it might be hard to get at to clean-remove the coating.

 

its easier to remove than that whale sperm/driveway emulsion that the factory used.

 

I epoxy prime my undersides than shoot bedliner you can get from the paint store on top of that, takes a special cheap gun they also sell .....................

 

Im with brigrat on that. I like it better than undrecoating.easier to keep clean too.

 

Spray can undercoating a friend put on his car always remained sticky and was a pain to work around when redoing the exhaust or putting on sway bars.

 

I say read the can or ask your paint shop guy if it can be sprayed on bare metal.

I used that 3M stuff all over on my 49, but not over bare metal.

 

Pay attention to what bears the product from the can to the surface. Some of the "parts store" undercoat brands, at least here in California, are water borne. I am not sure about others.

I am not a fan of spraying anything water borne directly onto bare metal.

 

I've used the roll on or brush on bedliner before with nice results. It dries hard and looks good also deadens the sound some.

 

Why not use an insulation type product inside the doors etc. I used some alum. roofing stuff I bought at Home Depot and lined the whole inside with it.
A lot less mess.

 

https://www.goapesonline.com/productdetails.asp?cat=Under+Coating&ID=728&pID=620

I like this stuff ^^^^^^

Dries fast, is super tough, thinning flattens the texture the thinner the flatter it lays, builds fast, and paintable in 30 mins. Used it on a van floor, covered a multitude of sins and holding up well to daily abuse.

 

I wondered where they got that stuff!! Do they have to extract it by hand??

 

I like the 3M, nice orange peel

 

Bed liner comes in spray cans now. I have used that as well as undercoat. I think bed liner dries faster and harder. I have used it on trunk floors and floor pans on OT vehicles ( think Jeep) where you would never use carpet.

 

I like to keep a couple of cans on the shelf. I stock up when they put it on sale. My cars won't be taking me to work in the snow anymore. I like the nice clean look that it gives. I use the "rubberized" type. Will it last another 50 years? Damn if I know. The car will out last me so I'm not too concerned about the next owner. He'll have to fend for himself.

 

The 3M is pretty bulletproof. On a project some time ago I had coated the floor pans with it - stood up to a last minute clearance issue corrected by a large hammer - didnt even phase the stuff. It doesnt stay sticky, I believe it states that it is paintable actually, not like the asphalt stuff. I would definitely paint or epoxy the bare metal first though

 

I like that stuff too, and if you don't want to spring for the gun, it rolls on great, and you can touch up the spots you miss with the same product in a rattle can. Works great, looks great, and it's tough as nails.

Brian

 

i have used the "MAR-HYDE" brand.and i would use it again though it stays soft, rubbery soft not sticky soft but i would never spray it over bare metal. ive always used an etch primer or an epoxy primer first.

 

POR-15 your bare metal, then spray or roll on bed liner... Bullet proof.

 

Id use paint

 

You'd be better off with a $45 quart of Por-15 applied with a brush. It will take less time to do....and you can throw it over the bare metal with no problem. I just did this on the model a I'm working on. Or get a $20 cheapie spray gun and spray it on, throw the gun away when you're done. If you're going to upholster the inside of the car then brushing it on will be fine. The blasted metal will give it some meat to bite on to also. $45 and a Saturday aftenoon and you'd be done. The rattle can undercoat would work, go on smooth, and last...but I think Por-15 would be better and easier to remove down the road if you have to change something. A grinding wheel will take the Por 15 off faster then heating and scraping undercoat.

 

Ya, after a couple years, you can peal off that POR15 in sheets to revel the rusted metal under it.

If you spray the cheap undercoating on, in a couple years you can recoat it because it it will be so thing you will be able to see through it.

The bedliner will make future welding nearly impossible, but at least it will last more then a couple years.

Paint it and be done with it. Gene

 

yep, read the label-look for short drying time and paintable. the asphalt based or some rubber based stuff does not ever really set up and dry. have used spray can undercoating inside fender wells, floors, trunks, frames, even firewalls. depends on how concerned you are about everything being show smooth or just functional.

 

Yeah never shoot anything over bare metal other than a self etch primer or sealer first, then your under coating, i think that its much easier if you have to do a repair later, then the bed liner stuff, and i have worked in collision repair for the last 25 years, just my two cents!

 

POR15 is designed to be Painted Over Rust, and with all the loose stuff removed. It cures in the presence of moisture. For it to cure all the way through, there has to be moisture all the way to where the paint is applied. This is the last thing you want over nice fresh bare metal. You will end up with rust underneath the paint. It may not have happened to you yet, but it is on the way.

 

What he said!

 

.....I painted first......then used 3 M.......five years ago and still looks good.....Have'nt driven in much rain yet, but seems to dry good with no peeling....

 

I can recommend that you don't use the Duplicolor rubberized undercoating. I used it on two projects with unsatisfactory results. It hardens and then cracks and chips off or cracks and lets water in and the rust starts.