Paint removal

[isisalar]

I slipped in the snow last week whilst putting a door on the roof rack on the silver HDI estate. Some paint from the door scraped off on the waistline of the car on it's way to the floor. I had painted the door a few days earlier with acrylic primer/undercoat(water based),and a water based gloss top coat.
The paintwork on the HDI is original and I'm keen to keep it that way, I don't think the paintwork is damaged itself.
I have found 'wonder wipes' to be excellent at removing paint and they're certainly going to be the first thing I try when it warms up a bit as I don't want to use anything abrasive and go through the laquer.
I fear that I may need something a bit stronger, can anyone say how the paint would react if I tried thinners, white spirit, or any other non abrasive cleaner? Or any other suggestions?
Kind regards
Paul

[dnsey]

You say that you want to use something non-abrasive, but personally I'd try metal polish, applied gently with a soft cloth.

[andy5]

Actually I'd prefer to use very fine abrasive rather than thinner

The car is probably also water based paint nowadays, so you'd be a bit pushed to find a solvent that affected one paint but not the other, and if you start softening or slightly dissolving the surface it might smear.

Personally, depending what it looks like, I might like to try first of all gently scraping the offending paint at a very shallow angle with the edge of piece from a broken sheet of perspex, used almost like a chisel, but I appreciate that not many people have this lying around, and if the car paint is fairly soft there's a risk of digging it in or scratching if it's not used shallow enough, so this might be a non-runner anyway.

Otherwise fine abrasive - I mean about 1500 grade and finer - on a small hard flat sanding block, and try to hit only the scraped-on paint with small sanding movements. If you sand it with a soft block then you will be more likely to also remove some of the surrounding lacquer and the area won't be flat afterwards.

A good tool for this would be a plastic bottle top lightly sanded over first if it has a sprue mark in the middle or is uneven, then put the abrasive on with double sided tape. Professionals sometimes use something similar for sanding out small paint flaws like lumps or hairs or insect legs, with specially cut scalloped edge discs about an inch across.

The trouble is it might be a problem finding the abrasive, as you don't want to have to buy a packet of 25 half sheets.

Then in a paint shop they use those compounding wheels but you can do a very small area by hand with a mildly abrasive polish like T-cut or brass or silver polish.

If it really is minor then just try the polish on its own before sanding.

[evilally]

I would maybe try a clay bar, or something like Autoglym Tar Remover.

[isisalar]

Thanks for the feedback so far.
The car paint is 14yrs on the car, and was as far as I know baked on at the factory so it wouldn't be soft.
I remember from my motor trade days that some cars, (vw/audi's & LTvans) I was told on a product knowledge course, had a sort of enamel coating which was unaffected by thinners at all.
I have since used a 'coach enamel' to spray large items and this was quite happy being thinned with white spirit or thinners, so totally confused.
Anyone got any direct experience with this or willing to test on a scrapper?
Cheers
Paul

[Gibbo2286]

Luke warm water should be all you need if the car paint is aged and the door paint is fresh, take your time, certainly not any sort of chemical solvent.

[isisalar]

All done.
I persevered with the Wonder wipes, and it must have taken all of 10 mins to remove every last bit.
I can't praise these things enough, they're like heavy duty baby wipes and will remove glues, paint, sealants, grease, etc, from hands or anything.
If you want a clean non shiny dashboard they're great, will remove week old paint from a steering wheel too.
Cheers
Paul

[citronut]

i'd use cellulose thinners on rag with thinners and another clean dry rag to wipe it of, or if your not sure on using that try petrol first or even meths,

even with modern water based car paints they still have an acrylic lacquer baked on over the top,

[qprdude]

I prefer T cut lightly applied.

[addo]

A modern (post 1987) finish in original condition and uncracked, may be readily cleaned with standard acrylic thinners. The finish is a catalysed, heat baked polyurethane that does not dissolve with most solvents (shy of actual strippers). Even caustic solution barely hurts.

The risk is only when repairs are effected in 1K which remains solvent prone forever, or a clearcoat is damaged, as basecoat colours are from acrylic emulsions which also remain soluble in thinners always.

Swirl remover is a super mild compound that can be used to remove (besides swirl marks) ink pens from breakers' parts and light contamination such as described.

[citronut]

I prefer T cut lightly applied.

the only prob with using an abrasive compound/T cut or the likes to remove paint is, you will be eroding the surface around the paint you wish to remove

[Timmo]

Even using a harsh compound on a machine polisher you'll be looking at 5-10 microns of paint, from a typically 120+ micron finish (30 micron base, 40 colour 50+ clear/laquer) so a bit of compound by hand is going to do minimal eroding of the surface, your typical respray is looking more at 300-450 microns thickness, a full 2 stage machine polishing (a medium grade followed by a ultra fine) will be 7-10 microns of the top/clear coat removed, the in between stages of the machining we use IPA to wipe over the panels to remove any residue, thinners Can remove the glossy layer from the top coat, ut only normally where a polish with a lot of filling agents in it,

many years back when a few of us from the Car cleaning trade got together to show the. Newbies of the 'detailing' how to use machine polishers, what compounds did what, polishes sealants wax's etc we did demo how you can burn through paint on a scrap door in the cleaning bay, 12" wool pad on the machine, Extra course compound, polisher at 3500rpm (max), big dave on the controls, full body weight on the head of the polisher, 90 seconds it took in one spot to burn through, panel was hot enough to steam water for a good few minutes after, - 306 dark metallic blue paint. Btw.
Tcut in itself is Not a good compound to use in the simple fact that it Does not break down as its worked, more often than not it causes more damage than it solves!

The resistance of the finish isnt down to years in the sun etc its down to what they use to cure them, Honda have very soft finishes whilst the opposite side are fiat, the metalics are rock hard, especially the late 90's /00's, vw do have a hard paint but the vans use a commercial grade which is tough as old boots! Ciroens, Peugeot, Renault etc sit in the middle of the paint resistance grades, Renault a little softer,

[citronut]

it also must depend on how hard the paint splash's/spots have become, the harder they are the more eroding around the splash/spot you will wear more of the surface finish away

[addo]

Timmo, how did you find the '90s/00s Volvo paint? My impressions (limited) are that it seems a beautiful blend of softness and durability.

[Timmo]

Addo, yes matey, a medium kinda strength to the finish but as you said, very durable! Then, they are made to withstand temperatures very often in the Minus degrees!!