I recently bought a LR touch up paint kit for my car as I want to fix some stone chips in the front bumper. The chips have all removed the black paint to reveal the white/grey undercoat below which is very visible against the black paint (the bumpers had been resprayed by the dealer I purchased it from). The kit came with some instructions stating that primer should first be applied to the chipped surface to make the paint stick to it. Is this necessary when applying the paint to plastic, too, or just when applying to metalwork?

Also it states to apply multiple layers of paint. Is this to bring the paint up level with the surrounding paintwork (if the chip is deep) or should the primer be used to do that? Thanks for any advice you can offer as I've never attempted paintwork fixes myself before... 2012 Vogue 4.4 TDV8 automatic (LHD), Santorini Black
2008 Vogue 3.6 TDV8 automatic (LHD), Java Black

Primer on metal, can be used to build up on plastic or as you said many dabs of top coat will build up chips.

Those touch up kits dont normally need primer theyre just to fill the chips but a good clean first with meths or panel wipe is needed to remove any wax etc. The brushes in them are normally useless as too big and you end up with a massive blob of paint. You should try snd use a tiny artists brush if you have one or tooth pick to put the paint in but its prety difficult to do neatly. After its done your best bet is to smooth it back with 2000 grit wet and dry or higher then buff it with some compound to shine it back up agin.

Good luck

Heres a guide from another forum which you may find helpful. Hope its ok to post it

http://www.detailingworld.co.uk/forum/showthread.php?t=153965

Hi,
A product called "Langka" was recommended to me, But I haven't tried it yet! Basically it is a system for flatting off your stone chip repairs so they blend in well, search google /you tube for info on use.

As above, the supplied brushes are useless and too big, I usually use a wooden tooth pick to clean out the hole, they're usually full of polish which makes then appear white, look even worse and won't allow the paint to stick.

I then usually just apply a drop of the paint into the hole with another wooden tooth pick, wait it to dry, flat back and repolish

Thanks for all the replies and the tip about the toothpick. I have dozens of the things to fix so it's going to take a while  2012 Vogue 4.4 TDV8 automatic (LHD), Santorini Black
2008 Vogue 3.6 TDV8 automatic (LHD), Java Black