Shiny black paint... milky portions after rain - PeachParts Mercedes-Benz Forum

locry · #1 08-06-2012, 06:49 AM

Ok, so i acquired a black car... it's uber shiny, a respray. Problem is, everytime it rains... and droplets are left overnight... the portions where the droplets sit turn a milky grey... after drying the spots will disappear. Same goes for the door jambs... where the paint contacts the weatherstrip... it'll turn a milky white until such time that it dries out completely... What could be the problem? Uncured paint? The hood and roof don't display such behaviour... the doors and both bumpers are much more susceptible.

Help!!!!

TX76513 · #2 08-06-2012, 09:16 AM

Mineral Deposits after the water evaporates. Nothing to do with paint. Put a good wax job on it - it probably has come from a detail shop and just has a glazing on it. Vingear and water will take the spots off before waxing.

TheDon · #3 08-06-2012, 09:38 AM

Also, before giving it a proper wax with a high quality wax. Wash the car with a dawn and water mix to remove any oils or wax.

As far as wax for dark colors, I use Poor Boys wax. $25 for a small tub and it lasts a while.

locry · #4 08-06-2012, 09:55 AM

Nope... it's not the usual mineral deposits that sit on top of the paint... I've encountered that and wax will indeed repel those. The spots on my paint cannot be felt... they are somehow absorbed by the paint. Once it air dries the white spots disappear on their own. The door jambs too... but those aren't white spots... they follow the contact surface of the weatherstrips... long white imprints of the weatherstrips. But they too disappear after drying for a while.
I don't really know much about paints but I think water is seeping through the paint. Nothing is bubbling though. It may need a sealant or something.

TX76513 · #5 08-06-2012, 10:08 AM

Since your thread title indicated the spots appear after rain, one can only make that assumption.

locry · #6 08-06-2012, 10:28 AM

Good point.

But it definitely isn't usual mineral water spot, at least that is solvable.

Zulfiqar · #7 08-06-2012, 11:26 AM

I know exactly what you are talking about and would love to know what causes it - I saw this same behaviour on a factory paint Land Rover discovery (dark green)

Not even the LR dealer had an answer (most probably they didnt want to answer)

locry · #8 08-06-2012, 11:39 AM

Factory paint?! Could it be uncured paint? I noticed that the well polished areas, like the hood, roof and trunk do not exhibit the spotting... maybe because those areas are constantly being baked by the sun? Thus cured properly? While the sides are not subjected to the sun as much... well that's my theory at least. I noticed the door jambs, which are the worst affected, are not that polished... maybe polishing somehow seals the surface better?

TheDon · #9 08-06-2012, 11:40 AM

Has the car been waxed?

locry · #10 08-06-2012, 12:35 PM

Yes... I've been waxing it to try and repel water... it works up to a point... we're experiencing regular rainfall for the past few days maybe my wax (turtle wax) isn't holding up too well from the constant water bombardment. I'm thinking of applying meguiar's polymer sealant or something, or klasse. Just to try and keep water away.
What's weird is my black paint job looks nice and shiny on a normal day. The white milky spots don't last very long once I wipe off the water, they're gone in maybe an hour or so.. no trace left.

TheDon · #11 08-06-2012, 01:13 PM

Wash off the turtle wax (dawn soap and water). Turtle wax is junk. Try meguairs or Klasse.

Zulfiqar · #12 08-06-2012, 01:22 PM

Yes the LR disco was a 300Tdi dark green color (not in the US) - it would look fantastic in the sun all polished and waxed, let it sit in rain and you had an ugly fungus finish disco for about 2 hours after it stopped raining or washing.

It was everywhere, door jambs specially. Lived with it.

I beleive we have a former paint maker on this forum - he would have some explanation.

oldsinner111 · #13 08-07-2012, 02:34 PM

your paint sounds like someone used a floor wax,either liquid or paste.I believe more so liquid wax.
I 've used Turtle wax for 40 years,with no harm but outstanding paint.

JohnM. · #14 08-07-2012, 02:58 PM

Might be worth paying someone to do a real circular polish on the areas that are exhibiting this issue.

Zulfiqar · #15 08-07-2012, 04:12 PM

@JohnM - this problem is not detailing or any other, I tried original zymol, klasse on it but it wouldnt help - this truck was not US spec. All cars I have seen in the US have a different finish from european and japanese spec cars - my experience on LRs Toyotas, Nissans.

If I had the truck professionally detailed - water would slide off while moving - but lets say you park it and it rained overnight - in the morning you would be greeted with milky splotches - remove water and let the sun evaporate the moisture - back to gleaming finish - It seemed that the paint was permeable.

My reason for posting here is that I thought no-one had ever experienced this problem, now I found one more person than me - similarly his vehicle is also not in the conti US.