Peeling bumper - prev damage? No primer?
Peeling bumper - prev damage? No primer?
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Discussion

Trailhead

Original Poster:

2,628 posts

167 months

Saturday 22nd May 2021
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Hi all,

My bumper has started to peel today when washing the car.

There’s no primer beneath the paint. Is this how cars leave the factory? Or does this indicate previous accident damage and a poor repair?

Car is a 2016 C Class Mercedes.


Belle427

11,085 posts

253 months

Sunday 23rd May 2021
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Looks like it's been colour coded but not prepped correctly.
Are these parts black normally on this model car?

Rockets7

476 posts

150 months

Sunday 23rd May 2021
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Battered with a jet wash or a previous bad repair.

Matt_E_Mulsion

1,744 posts

85 months

Sunday 23rd May 2021
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It's been some years since I've been out of the paintwork game, but they did move away from traditional primer to a clear coat of 'adhesion promoter' to achieve the same thing.

Either which way it appears to have lost its adhesion though either poor prep work or abuse by something like a jet wash as suggested above.

Trailhead

Original Poster:

2,628 posts

167 months

Sunday 23rd May 2021
quotequote all
Rockets7 said:
Battered with a jet wash or a previous bad repair.
Yes - it was the jet wash that did it. However I’ve never had this problem with a jet wash before.

Does anyone know if this should have had primer on and therefore is the result of a cheap repair?

Chris32345

2,139 posts

82 months

Sunday 23rd May 2021
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Trailhead said:
Yes - it was the jet wash that did it. However I’ve never had this problem with a jet wash before.

Does anyone know if this should have had primer on and therefore is the result of a cheap repair?
A lot of plastic parts font have a normal primer these days especially as they are provided prepaited at the factory's

Trailhead

Original Poster:

2,628 posts

167 months

Sunday 23rd May 2021
quotequote all
Chris32345 said:
Trailhead said:
Yes - it was the jet wash that did it. However I’ve never had this problem with a jet wash before.

Does anyone know if this should have had primer on and therefore is the result of a cheap repair?
A lot of plastic parts font have a normal primer these days especially as they are provided prepaited at the factory's
Thanks Chris.

So just my own fault then for jet washing a vulnerable part... that’s a shame... :-(

Defcon5

6,459 posts

211 months

Sunday 23rd May 2021
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Unless you were poking the paint with the nozzle of your nuclear powered jet wash I don’t think it’s reasonable for that to happen.

Thousands of cars are washed daily with a jet wash, and the roads aren’t full of half stripped cars.

How u doing

28,427 posts

203 months

Sunday 23rd May 2021
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Defcon5 said:
Unless you were poking the paint with the nozzle of your nuclear powered jet wash I don’t think it’s reasonable for that to happen.

Thousands of cars are washed daily with a jet wash, and the roads aren’t full of half stripped cars.
Plastics are particularly vulnerable, it only takes water to get under a stone chip and it'll lift off a strip of paint.

Have you seen what a jet wash can do to a paving slab or tyre?

Trailhead

Original Poster:

2,628 posts

167 months

Sunday 23rd May 2021
quotequote all
How u doing said:
Defcon5 said:
Unless you were poking the paint with the nozzle of your nuclear powered jet wash I don’t think it’s reasonable for that to happen.

Thousands of cars are washed daily with a jet wash, and the roads aren’t full of half stripped cars.
Plastics are particularly vulnerable, it only takes water to get under a stone chip and it'll lift off a strip of paint.

Have you seen what a jet wash can do to a paving slab or tyre?
To a patio, yes.

I think I’ll be chalking this one up to experience rather than heading down the warranty route.

Could be pricey.

mbwoy84

624 posts

132 months

Sunday 23rd May 2021
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Does the black layer feel shiny or rough?

Trailhead

Original Poster:

2,628 posts

167 months

Sunday 23rd May 2021
quotequote all
mbwoy84 said:
Does the black layer feel shiny or rough?
Smooth. Feels like untreated plastic.

V8covin

9,040 posts

213 months

Sunday 23rd May 2021
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Funnily enough I have a Golf in the workshop with exactly the same issue.
Just because you can't see primer doesn't mean it hasn't been primed because usually plastic is primed with an adhesion promoter which is clear and has no build thickness.
However as a repairer I've learnt the hard way, especially on front bumpers that are more prone to stone impact,adhesion promoter on it's own isn't enough.
I now follow that with 2k primer.

mbwoy84

624 posts

132 months

Monday 24th May 2021
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V8covin said:
However as a repairer I've learnt the hard way, especially on front bumpers that are more prone to stone impact,adhesion promoter on it's own isn't enough.
I now follow that with 2k primer.
This.

I never trust the "primed and ready to paint" new panels and always prep and re-prime them with a quality, proven primer.

If it is smooth and shiny underneath, it hasn't been keyed anyway, so the paint was never going to stay stuck for long.....