Paint / undercoat question...

damienh

damienh

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I know I may get a whole barrage of differing opinions on this subject, so, to narrow it down in the hope someone can advise - I have decide (rightly or wrongly) to use POR15 on the inside of the trunk/boot floor, and also underneath, so both sides, following some welding work I've had done around the fuel tank hole.

So I know all about what a pain to use it is, prep etc, and how great it is when it behaves, and how it can go wrong even when you follow instructions to the letter. Read all the marketing blurb like how it's so permanent it'll stay on your skin till the day you die etc, etc. Used it many times.

So forgetting about that side of it, I would like to paint the interior the same colour as the outside of the car, and the underside I guess black, but what to paint over the POR before adding topcoats ? and what topcoat on the underside ? Perhaps POR rubberised undercoating - or nothing ?

I have a can of their tie-coat primer, but that flaked off when I used it last time, even after scuffing as instructed.

Thanks in advance for any help, I had hoped to order stuff today but still can't work out a plan.

Damien
 
Damien, I like POR 15, but only on the repaired areas, in the automotive world I think it is not really used as a "base coat" say for an entire underside but just for those areas that have been welded or have some pitting. You can use a quality automotive primer on the majority of the underside and use any black paint/undercoat from there.

If you have POR 15 on the top side you can scuff it up, use primer on that and prep it for paint.

Hope that helps
 
Thanks Peter, that is helpful. I'd be inclined to agree on how POR is generally used.

I think it suits this application well, as there is only a small amount of shiny new metal, which it doesn't like. With regards to the scuffing, I really don't want to need to scuff it at all. It's too lumpy everywhere, with rough metal pinholes and welds, I'll go right back through to the metal on all of the the high points, I can't see how I could avoid that, never seems to work for me. I'm looking at using their etch primer before painting to maybe avoid that ? and, I'd never get in to scuff many of the awkward corners.

I have already started with POR15 on part of it ! so I'm kind of committed now.
 
I've used POR15 on rust areas and repair areas with good success. When I tried to use it in areas that did not need help, meaning, good metal and thinking it would keep bad things from happening the future, it basically flaked off over time.

I only use it in surface rust areas that need to be sealed and then paint over the top of it. Its always on material that is porous. My 2 cents...
 
Yes, a good self-etching primer is key, then your paint should stick well. I think the POR 15 adheres to itself better than anything else, that's why if it's on shiny metal it will come off in big flakes. I also think there is a way to reduce the POR 15 and use it in a good spray gun, the reducing may help it stick to the less rusty metal better. If I remember correctly there are instructions on how to reduce it. The money saved in reducing that stuff will easily pay for a decent paint gun :-)
 
I just had the underside of my car refinished
Looking through posts here, several people have said the original underside was tan / gray (not black)
I had mine painted grey (close enough I think)
Black epoxy primer, 'undercoat' then grey
 
I wonder if anyone has a code or picture at least of the underside grey colour ? I think I will paint grey over the undercoat. Someone recommended a gloss, even though it wouldn't look original, it would be easier to clean - thoughts?
 
In the E24 forums, we have pretty much determined the car, top and bottom, was primed, the underneath sprayed with undercoating and then finished with the body color. I have personally verified this when doing a total repaint and color change on my 6er,stripping, almost everythin, and repainting every possible spot in and out. The outer fender wells and underside floor boards etc. were all finished in body color. I used a single stage paint with hardener for the finish coat on the underneath

We sprayed the undercoating on the bottom while laying on our backs ,in some painters coveralls, and it was still a mess, spraying the color was fun too.
 
anything

what i used was the good ole plasti dip
spray
the stuff is great it provide an almost flat look that follows your existing texture
so it looks and works as originally intended. the look especially thats really quite impoortant not to change the original textures and finishes
not too many people here have ever mentioned that which really is the most important thging when redonig these monsters.
loose the textures---- loose the car.
 
HB Chris said:
So Plastidip comes in grey?
Click to expand...

you can get it in just about any color. There is a whole world of plastidip enthusiasts. Check out www.dipyourcar.com. Plastidip isn't permanent. If you lay down enough layers, you can peel it off like elmers glue on your fingertips. Gasoline and other solvents like goo gone will wipe it off also.
 
Just trying to throw out info. I don’t know how it applies to an E9, but is accurate for an an E24

I power washed the underneath of my car before painting. Some of the existing under coating did peel off, but it was for sure body color over undercoating down to bare metal.
 
Undercoating

First let me say that one of our truly expert forum members mentioned at one time that all US bound e9's came from the factory without undercoating. That being said, from the e9's I have worked on, ranging from 1969-74 I have found that the bare metal is primed after the seam sealer was brushed on, then a light putty, almost white, undercoating was applied, this undercoating is very tough and if it is stuck on well in my opinion should be left alone. In those areas where there is rust or damage the bare metal should be re-primed and then you'll need to find an undercoat that matches the original as close as possible (there are suggestions below). You can feather it in so the texture and thickness match as close as possible and then top coat it. Let's assume that the dealer installed all US e9 undercoating, then you would have license to undercoat as appropriate to your area of the country, including simply priming it and painting it the body color. I for one would stay away from the bed-liner approach because once that stuff is on it will never come off if other repair work is necessary.

Others may know much more than I so if I'm in error sorry-
 
Texture under paint

Power washed the wheel wells on my e3, I can see a undercoat texture under the paint.
 

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Bob, that looks like the chip guard. On US coupes, primer is very thick and appears to be tan color, almost khaki/yellow or something close. Body color is oversprayed around edges, not everywhere. I think dealers applied undercoating, it is found on the window stickers, and it is grey. Years of oil, grease and dirt turns it black.
 
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