How to prep a plastic bumper for spraying


MB Enthusiast
Mar 9, 2011
Swansea, Dubai, Riyadh
1997 W140 S600L/2003 S211 320cdi
I've picked up used front a rear bumpers with the intention of using these as part of the process of mono-toning my W124 and thought I may as well have a crack at prepping them myself.

having sanded back all of the gauges and scrapes, there are still some fairly shallow scratches in the sanded areas. Would it acceptable to use platic primer on the bare plastic areas, then build it up using filler primer on top? or is it best to use a plastic filler to bring it back level before priming?

Additional dumb questions....

The bumpers and inserts are Azurite Blue, and will be sprayed Malachite Green. Is it o.k to simply wet sand to 1200 before spraying? or would the finnish be better if they were primed as well prior to spraying? if so, is it safe to assume regular primer is o.k, or should plastic primer be used over the whole area? I intended only using plastic primer on the bare plastic areas, then covering the whole of the bumpers with regular primer.

It seems there is too much info out there on t'internet and too many conflicting opinions, hence advice being sought here.

Thanks in advance.


Nov 5, 2008
CLK 430
Hi Millo777,

best thing to do is flat the entire bumper with 320 grit fill any voids with 2K stopper
and 2K primer the whole bumper no need for plastic primer cause its already been
sprayed in colour, flat back 2K primer with 500 or 600 grit then apply Malachite green
base then overcoat with clear coat

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