Paint/protection Process.

[daza2020 2]

Hi all.

 

I'm slowly getting round to getting my gti back to it's former glory but seems to have come unstuck, I'm at the stage now where I've got the rear bumper off and slowly getting the beam and fuel tank off then it'll be on with the wire wheel I'm planning on taking it back to bare metal and treating it............ this is where I'm stuck how would I go about it.

 

From my general looking around I know I'll need a primer then colour, then stonechip I would prefer to be able to buy the stuff that needs brushing on as I don't want to coat the house/car/pets in overspray.

 

Thanks.

[mowflow 67]

Doing the same job myself. I've been doing it for forever. I am a slow worker but it is a horrible time consuming dirty job and doing it lying on the cold floor of a small garage with the car 6 inches from your face on axel stands is less than ideal.

 

I decided to do it in 2 sections. First I did up to the ledge that the tank sits on back, cleaned it all, got the primer on it then did from that ledge forward including the chassis legs. I've had a fair bit of cutting out of rust and welding new steel in to do. Part of the problem was having to learn how to weld on the fly, got the hang of it now that I've finished.

 

I did the following:

Cleaned to bare steel using twist knot wire brushes on a grinder

Cleaned further with softer wire brushes on drill

Rub with scotch brite pads

All areas of rusted steel that were still solid but pitted when cleaned were treated with Bilt Hamber deox c then Hydrate 80

Surface cleaned several times with panel wipe

3 coats of Jotum 87 epoxy mastic primer brushed on

Grey stripe seam sealer brushed on all seams

Gravitex stone chip protection sprayed on

All cavities filled with Bilt Hamber cavity wax

 

I've not decided if I'm going to over paint and don't know if I have to. Fortunately the car is white so I could use white Jotum and gravitex. I have a compressor but don't want to get into air fed masks and poison paints.

 

I'm not saying the above is the way to do it. I did a fair bit of reading on various car restoration forum threads and this is what I came up with. It's the first time I've done anything like this myself and I want it to be the last....... At least on this car.

[DamirGTI 342]

Don't bother taking all the underside down to the bare metal , it'll be too much job and way more dirty ! just concentrate on the areas with rust specks , areas with peeled/cracked factory underside stonechip/seam sealer surface and stuff like that ..

Thing is , if you take it all down to the bare metal you'll never be able to seal up the floor pan back as quality as it's been done from the factory .

 

Pressure wash all the underside of the car , clean up all the rusted areas with wire wheel as best as you can and treat afterwards with good quality rust converter , can spray primer over the rust converter layer but it isn't essential , the rust converter leaves polymer layer which is an really good primer/adhesion layer as it is and usually doesn't need additional primer over it .. just repainting/sealing with an layer of paint and layer of stonechip coat will do , but as you wish can prime it as well if wanted .

Other areas which are rust free and you clean them all the way down to the bare metal , spray with few layers of zinc rich primer , and do that as soon as possible cos bare metal surface will catch rust microscopically really fast if left for certain amount of time without protection .. Ideally as soon as you clean up the area - spray the bare metal at once to seal it . Further , as above apply few coats of paint and stonechip coat on top .

 

All other areas on which the factory stonechip layer is sound/undamaged , wipe off clean and reseal with the fresh layer of stonechip coat .

 

When you're done with the entire floor pan surface , when all is sealed up with stonechip coat , can paint it over to aid further protection .. if opted for repainting , leave the stonechip coat to "flash off" for a few days before putting the paint on top cos if you paint it at once after applying stonechip coat you'll have problems with paint adhesion (as the stonechip stuff contains rubberised compound , it'll shrink a bit while drying .. so if repainted while it's still fresh the paint will not adhere properly and will crack up as the stonechip coat dries/fully hardens ..)

 

All the listed products : rust converter , zinc rich primer , paint , stonechip coat , are available in either brush in or rattle can/spray form .. though for best quality job , the stonechip coat would be better applied with an air compressor .

 

D

Edited January 28, 2014 by DamirGTI

[mowflow 67]

.....

 

Thing is , if you take it all down to the bare metal you'll never be able to seal up the floor pan back as quality as it's been done from the factory .

 

.....

 

I kind of agree with that. You won't be working with the space and the clean steel that they had at the factory so an instant disadvantage.

 

Peugeot did do a good job with it but I found that areas that looked absolutely fine did reveal at least some surface rust underneath. A small crack in the coating can let water in and it seeps a long way. For that reason I decided it was best to just do it all.

 

The other point is that coatings have moved along in the last 20 years since they built the car. They used to continually paint the Forth Road bridge but that new high solids glass based paint they did with recently means it won't need to be touched for decades. I did a lot of rather boring research on surface coatings before I did mine and there are some brilliant products about now on the marine side of things. If it can stop oil rig legs rusting in the North sea i'd guess it's good for the underside of a car.

 

In saying that "If it ain't broke, don't fix it" still applies.

[daza2020 2]

I would prefer to leave it all alone, however it is now at that age where there are bits of surface rust forming and it its not sorted then the rot will set it. There's bits where the underseal is missing.

 

I'm planning on also redoing all the seam sealing as again the guy must of been asleep as there's patches missing.

 

So far I've got in my head to use rust bullet then a high zinc primer on top with stone chip on that then a top coat of colour which should keep it going for a while yet.

 

However where I live there is a great many boat shops so I may also ask around there as anything thats made to protect against sea water should be more than fine for the bottom of a car thats going to do less than 500 miles a year in the dry.