Getting cement off paintwork(not a joke)

[Mikesmerc]

Washing my CLK the other day I noticed some dirt splashes behind the front wheel that didnt come off during washing, under further investigation I found that it was cement. Worst case.....sand off cement and repaint?. Any one any brighter ideas?
Rgds
Mike

 

[996jimbo]

If you sand off the cement you may be down to the metal surrounding the cement spot before you get the cement off. I'd suggest either leave it and hope it comes off in time or trying to pick the cement off and see what mess you're left with.

Are we talking much and very noticable?

I'm sure there are products that would remove the cement but not sure what they would do to your paintwork.

 

[Myros]

desperation

would have me gently chipping away with a plastic spatula or something else not too painful if I slip. I can't think of anything that will get rid of cement without dissolving your car with it. that's why we use it for building things with.
A chat with a paint shop expert is on the cards here Mike.or spray the whole car in cement.

 

[Mikesmerc]

Thanks for the sugestions, splatter is covering bottom of the wing and some of the door. Streaks of cement a couple of mm wide. Dont fancy the sanding option but I might give the plastic scraper a go.

Will keep posting on my progress, or lack of it.
Cheers
Mike

 

[996jimbo]

or spray the whole car in cement.

Should suggest this to MB - it'd cure all the rust problems.

 

[Mikesmerc]

And no fear of it chipping off:?

 

[television]

There are products on the market to remove cement,you buy it from a builders merchant. Cement splashes are water soluble, if you kept the area wet it would disolve. Malcolm :wink:

 

[R129]

The slow way is to apply a solution of citric acid (kettle descaler)and water to the area and keep it moist, this will slowly dissolve and lift the cement.

Quicker way is 28% Hydrochloric acid with an inhibitor in to stop it attacking the paint. Should clean it up in a few seconds and will wash off with plain water. This is the stuff the builders merchants sell and it should not affect the paint, although best to try it on an inconspicuous area first as they say.

 

[davidsl500]

If you go the acid route then I would (seriously !) give the area a good polish with a decent resin polish first - the sort that you see demonstrated with people setting fire to lighter fluid on the bonnet and throwing battery acid over the paintwork....

 

[paulcallender]

If you go the acid route then I would (seriously !) give the area a good polish with a decent resin polish first - the sort that you see demonstrated with people setting fire to lighter fluid on the bonnet and throwing battery acid over the paintwork....

There are 3 possible things to try:

Acid, eg lemon juice (citric acid)
Chemical-based polish, eg as suggested above
Friction-based polish, eg T-cut

Since cememt is an alkali, I'd try the acid route first. Start with mild acid (lemon juice, vinegar) then work upwards. You are aiming for an acid strong enough to remove the cement, but weak enough to leave the lacquer undamaged. You may find that the cement has gone into the surface of the lacquer, in chich case you're looking using a friction-based polish for a small area. You might end up with the area looking odd because it will be a better resultant finish than the rest of the car!

 

[Apial]

Have you tried a pressure washer?

 

[190D]

Why not try diluted brick cleaner and apply it with a brush to the affected area to soften the cement then wash of with water it shouldn't harm the paint work

 

[Mikesmerc]

All this talk of acids is starting to frighten me, though lemon juice sounds harmless enough. I work across from a builders merchants so I will pop in and see what they have got. T-cut just seems too arkward to use as the steaks of cement are only a couple of mm wide and a couple of mm high. I presume its after burning its way on to the lacquer . Must take a pic later and post it.

Thanks to everyone for the suggestions.
Regards
Mike

 

[shayes]

You should try living on the Seafront. The Birds poo the stuff on the cars all the time.

I find something akin to blotting paper left moist on affected area once it has become baked on, is best way if not that time of the year for early morning dew.

Thumb nail the next weapon of attack!

Just had to scrape off something looking more like specs of Radseal which were on car when I acquired it a week ago. Has cut through to the colour and faded it. May have even been tree sap?

 

[Mikesmerc]

My old 230e is parked under trees all the time and at cetain times of the year it gets covered in sap. Some soapy warm water gets it off with no effort. Never has effected the paint. Had bird droppings take a layer of paint off once but I blame cheap Paint. One thing that will do damage is brake fluid, found out the hard way as a child on a mk2 Jag..oops.

Rgds
Mike

And heres a pic of cement...and usual road dirt

 

[davidsl500]

My old 230e is parked under trees all the time and at cetain times of the year it gets covered in sap. Some soapy warm water gets it off with no effort. Never has effected the paint. Had bird droppings take a layer of paint off once but I blame cheap Paint. One thing that will do damage is brake fluid, found out the hard way as a child on a mk2 Jag..oops.

Rgds
Mike

And heres a pic of cement...and usual road dirt

Lime trees are the worst apparently - its not so much the limes themselves as the bugs that feed on the sap and then deposit the modified contents downwards - a really sticky mess

 

[television]

There are 3 possible things to try:

Acid, eg lemon juice (citric acid)
Chemical-based polish, eg as suggested above
Friction-based polish, eg T-cut

There is a snag using any form of polish, you can only disolve the cement content. Once you have taken away the cement you are left with sand and one grain in the cloth will do a lot of damage. One other snag is that if this mix of cement was for rendering, the sand will be very coarse and it would have a waterfroofer added to the mix,even dedicated removers do not work well on this mix. just picking at it with your finger nail over a period of time will do it.
Malcolm

 

[paulcallender]

There are 3 possible things to try:

Acid, eg lemon juice (citric acid)
Chemical-based polish, eg as suggested above
Friction-based polish, eg T-cut

There is a snag using any form of polish, you can only disolve the cement content. Once you have taken away the cement you are left with sand and one grain in the cloth will do a lot of damage. One other snag is that if this mix of cement was for rendering, the sand will be very coarse and it would have a waterfroofer added to the mix,even dedicated removers do not work well on this mix. just picking at it with your finger nail over a period of time will do it.
Malcolm

Yes, the sand will potentially scratch into the lacquer surface. Hopefully its deep enough to polish out, leaving an invisible repair. If not, you might have to resign yourself to a trip to the paintshop.

 

[paulcallender]

What happened in the end???

 

[Mikesmerc]

Sod all Im afraid, have the car up for sale, the wife says she doesnt want it anymore, says shes too used to her 4x4 and couldnt go back to driving a car. So, Im going to buy an eary 90s 500SL for myself when I have the CLK sold.
Think I will leave well alone with the cement and other annoying little faults. Thanks to everyone for the help.
Regards
Mike