Undercoating removal.. is sandblasting the best?

I'd like to remove the factory undercoating. After numerous Google searches I see heat and scraper works, knotted wire wheel on angle grinder, oven cleaner gets mixed reviews and even a dry ice method on the floor freezes it and it chips off. I tried the first 2 and man, this will take forever. I did find a mobile sandblasting comapny that said he would prefer for me to get most of it off by hand before he comes out.... but man I don't have the patience for scraping by hand.

What have you guys done or has worked best?

Do you think sandblasting will work without me spending 2 weeks scraping by hand first?

 

Mobile blaster might pi$$ off all the neighbors........ The compressor he would need to do the job would be a trailered diesel.... ==== LOUD....

For some reason I don't think he has a large comp like that.. That's his reason for you to get most of it off... You will need a ramp truck to get the rotisserie to a SB location......

You will then need to mask off the rotisserie to prevent sand from entering every nook and cranny.....

 

I've heard a dry ice blaster does well. Not done it myself and only know of a place in Florida that will do it to cars.

 

I live in the country on 76 acres so we're not worried about the noise. He does have a diesel compressor and said his equipment is good enough to blast a water tower or bridge. If i didn't scrape most of the big chunks off I think he would have to use a very coarse sand and then go over it again with a lighter sand.... that's his reasoning I believe.

 

I also tried the heat/scraper method. No way - takes forever and still never really comes completely off. I spoke with my mobile blaster about removing it. He said no problem. Sure enough. Blasted down to clean metal. Look at the pics in my thread. Cost me $500, best money I've spent.

 

Car looks good Yeah probably going the sandblasting method and he said about $500- $650. My only problem with this is that the inside floor and trunk are painted already so I am afraid the heat from blasting will damage the paint. I wasn't going to do the under body at first. Now I am in this dilemma.

 

Easiest way to remove old undercoating and sound deadener that I've found is using heat, but not any heat source lol.

I use a halogen work light (they get hot) and heat up the metal from the opposite side.
The trick is to heat up the metal that it's attached to NOT the old material itself!

Heat the metal up a couple of minutes and it will be soft and easy to scrape off.

I can do a whole door, wheel well or quarter panel in 5-10 minutes using this method.


Keith

 

The best method depends on the condition of the undercoating.
If it's hard and brittle, a Harbor Freight needle scaler works great. You need to attack the undercoat at an angle, you kinda get under it and chip it off.
Dry ice will also make it hard/brittle, making it easier to chip off.
Sandblasting works best on uc in this condition too.

Soft/gummy undercoat is the worst. You'll have to scrape it, dissolve it, or wire wheel it from the top surface down to the base metal. not fun. Heating it or freezing it helps.

Sandblasting works best by getting under it, lifting it off. If you try to wear down the uc from the top to the surface, it takes forever since it's soft and resists the blasting. It may or may not work well for your car.

 

needle gun - harbor freight or eastwood sells them for not much $$$. But, as Walt said, it need to be hard/brittle.

 

It's not hard/brittle unfortunately.

 

I priced Dry Ice blasting here in KC area and it was $1400 and would be the best but costly. Sandblasting is second choice if you want to repaint everything.

 

I did it myself with dry ice on my 66 T-bird. It becomes very clean and not abrasive like sand. You need a professional system and a large compressor that provides a lot of pressure and a lot of air volume. In addition, it must be equipped with good water and oil separators.

It took me 12 hours and about 1,800 pounds of ice to get it clean. It's a loud and dirty job, but the result is great.

Emmanuel

 

Try the dry ice behind it like Walt said. Maybe it will get hard enough.

 

Can't find anyone to dry ice blast and the machines appear to be about $2000 so that's ot an option for me.

I tried a few methods.... drill/ wire wheel and then heat gun and scraper.

First pic is what I am dealing with.

Second picture is driver side using a heat gun and scraper and then a quick pass with the wire wheel to clean it up a bit. Although very very time consuming it worked fairly decent but hard to get in all the cracks and crevices... and still leaves a thin residue of gooey tar like substance. 3 hours and only got from the front of the back seat area to the firewall on the driver side only. I am sore as heck.

Third pic is driver side from rear sear back. Used the knotted wheel on angle grinder and wire wheel with drill. This does not work very well and does not remove all the under coating.

I guess heat gun and scraper it is.. this is gonna suck haha.

Anyone know what might remove the sticky tar residue? Oven cleaner maybe? I need to find something that won't remove the exterior paint if I decide to keep the same color.

Or I wonder, since the heat gun method gets 90% of the coating off, will the sandblasting need less pressure casting less friction/heat and won't mess with the paint?

 

No, sandblasting doesn’t work well at all on soft surfaces such as undercoating, it absorbs the impact of the sand and takes a TON of sand AND time (duration) which also allows time for the sand to find its way into EVERY crevice.
What you’ve done so far is perfect!
Yes, it’s a **** job, and it takes awhile, but your FAAAAAR better off doing the way your doing it instead of sand blasting!

 

Just wait till you attempt to remove that tarry sticky stuff from the roof that's under the headliner if you decide to do that.That's a sticky,gummy mess. I have only had it hard and peel off once. I had to remove it to get the mouse urine smell out of the car, But,it looks like you are making progress...Keep on keeping on!

 

I would put that heat gun back in storage and find a halogen work light to use for your heat source.

If I was there I would show you how fast and easy it is with a halogen light.

Remember the trick is to heat the metal up that the undercoating is attached to!

Other people have used the halogen work light trick and they ALL have said it was easy peasy.

Now go get yourself a halogen work light and do it as I described and you will be amazed at how easy it is.

Keith

 

Thanks guys.
Keith, problem I have is that I should have done under the car first. Inside floors are painted and trunk is sanded and painted with Eastwood trunk paint and clear coat. The sound deadener is also installed on the inside floor. I don't think I can heat from the other side in risk of damaging the interior paint. Maybe I'm wrong.

I think I would still have some minor residue and need to know how to get that off.

Maybe tar remover?

 

Simple Green, if not then acetone or lacquer thinner.