Cement on car body

Discuss anything after that final masking comes off.



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PostPosted: Mon Feb 14, 2022 6:41 pm
Recently the county resurfaced the road which I live on. They dug up the old surface and put down what looked like a limestone surface before they put blacktop over it. During this time we had to drive our cars over it and it has the appearance of going through mud puddles until today when I tried to wash it off. I think they must have added portland cement into what they were doing because it won't wash off no matter how long you soak it. It's completely impervious to water. I picked a little of it off with my fingernails but there is too much of it. I'm wondering what is the best way to clean it off without ruining the paint? It has a urethane clear coat on it.

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PostPosted: Tue Feb 15, 2022 12:42 am
I ran into this same thing about 15 years ago on one of my leased cars at the time. I think you are correct about what caused this. I know for a fact that they used to add concrete mix dust to a lot of the loose stone on bad roads in the town where I grew up. So I ended up soaking a rag with some of that Goof Off stuff on it. I left the edges of the rag dry so I could use painter's masking tape to hold it over the area. After an hour or so I took a new safety razor blade and put some tape over each edge/end Leaving only the middle half of the blade exposed and slowly kept running this over the stuck on stuff. This is the same method you might use to razor down clear coat runs. I not going to kid you, it ain't easy but when you get it almost down near the paint it kind of picked off clear with no damage to my clear.
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PostPosted: Tue Feb 15, 2022 11:06 am
Thanks, I will give that a try. I can't believe cement would bond that well to cured urethane. So far all I did was soak it with car wash soap and hit it with a power washer. Before making it worse I thought I might get some info from someone with experience.

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PostPosted: Tue Feb 15, 2022 11:48 am
So why does that crap stick like that to clearcoat? That is a question I asked one of my old wood finish chemcial instructors. He said that it probably involves the ability for it to "etch" somewhat into the clear coat. It's something that it wasn't designed to do, it's more like just a by product of how it reacts with water.
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