Underseal

[onthames]

The PO of my car had horrible black sticky Schutz style undersealed installed and it's flaking and trapping moisture. I plan to strip it all off. What should I replace with?

[flybynite]

The PO of my car had horrible black sticky Schutz style undersealed installed and it's flaking and trapping moisture. I plan to strip it all off. What should I replace with?

Black death, nasty stuff. Pig to get off. Are you doing it somewhere you have air and spray equipment?

Generally now it is epoxy primer, then something like 3M bag for stonechip and texture then top coat.

Frost have a good range of stuff if doing it by hand

https://www.frost.co.uk

[onthames]

The PO of my car had horrible black sticky Schutz style undersealed installed and it's flaking and trapping moisture. I plan to strip it all off. What should I replace with?

Black death, nasty stuff. Pig to get off. Are you doing it somewhere you have air and spray equipment?

Generally now it is epoxy primer, then something like 3M bag for stonechip and texture then top coat.

Frost have a good range of stuff if doing it by hand

https://www.frost.co.uk

Yeah got air and can get some spray tools. Was thinking heat gun and a scraper? Or maybe petrol but don't wanna damage the paint underneath as I flaked some off and still looks good. A 79 year old mechanic friend told me to wait till winter and do it on the coldest night with a hammer and chisel (carefully).. apparently flakes off. I may replicate this technique with some dry ice?

[flybynite]

Aah I get you now, when you said flaking off I thought it was rust underneath. If it is paint then yes it depends on how dried out it is. Cold and break it off may work but if it is too soft then it is a messy job with a blunt scraper heat and turps. Where are you trying to clean it off from and how much of it is there?

[onthames]

Aah I get you now, when you said flaking off I thought it was rust underneath. If it is paint then yes it depends on how dried out it is. Cold and break it off may work but if it is too soft then it is a messy job with a blunt scraper heat and turps. Where are you trying to clean it off from and how much of it is there?

It's schutz underseal, sticky and basically like bitumen... It's fucking horrible!!

[DanThe]

Dry ice blasting may remove it and leave the paint untouched, I expect it will be expensive but not as expensive/horrendous as the back to bare metal and start again process

[onthames]

Dry ice blasting may remove it and leave the paint untouched, I expect it will be expensive but not as expensive/horrendous as the back to bare metal and start again process

Thinking I may just stick a bag of dry ice on each area and then see if I can peel off. If not will look into blasting

[martauto]

viewtopic.php?f=1&t=282475&p=2985635&hi ... g#p2985635

I dont know if it`s avaliable here or how much but may be worth looking in to.

Mart.

[rix313]

I use Dinitrol 445 Black Polymer Stone Chip. Very good coverage and impact resistance. I buy it from a company called Rejel who are beyond helpful

[steve_k]

The PO of my car had horrible black sticky Schutz style undersealed installed and it's flaking and trapping moisture. I plan to strip it all off. What should I replace with?

Black death, nasty stuff. Pig to get off. Are you doing it somewhere you have air and spray equipment?

Generally now it is epoxy primer, then something like 3M bag for stonechip and texture then top coat.

Frost have a good range of stuff if doing it by hand

https://www.frost.co.uk

when i cleaned all that crap from the underside of mine i did all the above (epoxy primer, 3M stonechip & then top coat) yet when i went for mot last week the tester was moaning about it & put it down as an advisory that it prevented a proper inspection of the underside.

as for cleaning that crap off i heated it up using a heat gun & scraped it off with a plastic scraper & a wire wheel on a drill to get the rest off. seemed to work pretty well.

[flybynite]

when i went for mot last week the tester was moaning about it & put it down as an advisory that it prevented a proper inspection of the underside.

I get that advisory on some MOTs on all my cars because of the undertrays, funny thing is some years I don't get it on any yet the undertrays don't move. Down to the individual MOT tester wielding their little bit of power.

If it was the 3M underseal he was moaning about, did you not tell him that's how the bloody thing came from the factory? (except that it was beige on most parts)

[onthames]

I started removing some with a pry bar and there is surface rust where the underseal has began to flake off. It looks like its been put over factory underseal. The only area I found that will need welding is at the front nearside jacking point. But I may find more.
Should I strip off all the new and old underseal, prep the metal, paint and do again? Hoping I can keep the paint in most areas as ive gouged out small areas of underseal in various places and the paint under is fine, no rust as far as I can see. So, it hopefully will just be small areas that need work, but all the underseal needs to go and be redone.

PXL_20210913_130652483.jpg

PXL_20210913_130656705.jpg

PXL_20210913_130704443.jpg

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PXL_20210913_130833904.jpg

[onthames]

Here's the layers. Black = po bitumen type underseal
Yellow = factory underseal
Grey = primer
Silver = metal

It seems surface rust so far. Crossing my fingers.

PXL_20210913_132800028.jpg

[onthames]

So, after investigating further, it looks as if only some smallish areas need to be redone. Is it possible to remove the underseal and paint on these areas, repaint and underseal over and slightly over the existing to create a new seal? Or is it the case of having to redo the whole car in one layer ...
Oh god...

[flybynite]

So, after investigating further, it looks as if only some smallish areas need to be redone. Is it possible to remove the underseal and paint on these areas, repaint and underseal over and slightly over the existing to create a new seal? Or is it the case of having to redo the whole car in one layer ...
Oh god...

Don't get me wrong, I am a big fan of doing the whole of the underside together as the only way to guarantee a complete cover, that will be what both of mine get. But it is a big job and IMHO unless you really go to town there is no point.

You can do perfectly acceptable spot repairs, just take it all back until you have got a good margin of clean metal, then take the schutz crap back to leave a good margin of original underseal.

If you can take the original underseal back to leave a margin of original e-coat but that is easier said than done.

Do the repairs needed and make sure you use some Jenolite around it to catch any missed rust. Spray some epoxy(or etch) primer and blend it into the e-coat. Spray or brush some 3M 08800 underseal or if not some upol 'stonechip' and blend it in to the factory underseal. As soon as it is dry, satin black should blend it in.

[onthames]

So, after investigating further, it looks as if only some smallish areas need to be redone. Is it possible to remove the underseal and paint on these areas, repaint and underseal over and slightly over the existing to create a new seal? Or is it the case of having to redo the whole car in one layer ...
Oh god...

Don't get me wrong, I am a big fan of doing the whole of the underside together as the only way to guarantee a complete cover, that will be what both of mine get. But it is a big job and IMHO unless you really go to town there is no point.

You can do perfectly acceptable spot repairs, just take it all back until you have got a good margin of clean metal, then take the schutz crap back to leave a good margin of original underseal.

If you can take the original underseal back to leave a margin of original e-coat but that is easier said than done.

Do the repairs needed and make sure you use some Jenolite around it to catch any missed rust. Spray some epoxy(or etch) primer and blend it into the e-coat. Spray or brush some 3M 08800 underseal or if not some upol 'stonechip' and blend it in to the factory underseal. As soon as it is dry, satin black should blend it in.

Do you know how thick 3M 08800 goes on? As the original underseal surrounding is quite thick

[flybynite]

Do you know how thick 3M 08800 goes on? As the original underseal surrounding is quite thick

It can go on quite thick, depends if you are spraying or brushing. Have a look at some of the videos done by Redish Motorsport or Spencer Latham (BMP)

But all you really need to do is protect the repair, matching the depth of the original is less important.

[onthames]

I picked up 10kg of dry ice today from a lovely little company in ipswich. Gonna try it to remove the underseal without removing paint. Will update later