There are many times that you may want to paint the plastic parts inside of your vehicle.
With the right preparation and paint selection you can normally get pretty decent results however there are some drawbacks to painting plastic parts that you should understand before you attempt a large project.
The first thing you must realize is that plastic parts have color embedded in the plastic for one reason. Any high wear area that has a paint finish over plastic will deteriorate relatively quickly because of adhesion problems.
The best thing to do when you have a plastic part that needs to be restored that is in a high traffic or wear area is to simply to replace it. Unfortunately sometimes when you are hunting down parts for an older vehicle you will need to rely on used parts and a factory color match may not be possible.
If you are working on a vehicle that is less then 10 years old it is probably in your best interest to simply call around to a few junkyards or try to find the used part online.
Things I would never paint include: Steering Wheels, Door Handles, Cargo Area floors and possibly side panels, Floor Peddles, Shifter Handles.. basically any area where you know you or items in your vehicle will come into contact every time you use the vehicle.
If you have vinyl seats it is possible to do a change over color but you should expect the color to chip off in less then a year. Most or many products will say that you can expect 3 to 5 years and this might be true for a rear or passenger seat that does not see much use but the drivers seat will see chipping relatively quickly.
Leather may give better results for color changes on seats because when you restore or color change leather seats you are actually dying the seat and the color penetrates the leather slightly better.
How To Select the Right Paint and Primer for Plastic Parts
Most plastics used for interior parts are vinyl based molded parts but you may find some poly butyl parts used for cargo areas or kick plates. Vinyl is also used for a leather alternative on panels and seat covers. The way to know the difference is to do a burn test where you slice off a tiny sliver on the back of the part and burn it with a match but since none of us are going to do this you can usually pick a non vinyl part when you can use your fingernail to press into the surface and the plastic part gets a gouge in it.
Vinyl parts can be painted with special vinyl paint and primer. You will want to ask your paint supplier about what products they carry however you may want to look at the SEM line of paint products.
For other plastics you will have two choices .. clean and paint with enamel that has a flex agent or see if your paint supplier has a product they suggest.
Vinyl parts should be cleaned with a special etching agent.
I suggest that you first clean the part with mild soap and a scotch brite pad .. scrub lightly to scuff the surface without causing damage to the surface and its texture.
You can also use a product like Sand Free in areas that are difficult to sand or scuff with a scrub pad but only use them as a last resort.
Other people suggest that you can use a clear primer .. it looks like clear but provides some adhesion. This may be an option if you clean the part well then use it as a tack coat.
Painting Plastic Parts
Unlike other parts you definitely want less paint on the part and you want to use a flexible paint.
You may believe that you can put on a heavy coat of paint to increase durability but in the end the flexing of the plastic part no matter if it is just from heat / the sun or from pressure on the part will cause that paint to peal and chip.
A thin coat will flex with the part.
Make sure that you have good color hiding and then if necessary top coat the paint with clear that has a flex agent.
How important is it to use specialty paints when Painting Plastic Parts?
If you could get away with using exterior paint on your interior plastic parts then no paint jobber would ever carry the specialty paints. However we are talking about projects that may or may not meet the ability of the paint manufacture to deliver a specific color.
If you have a stable plastic part that will not see much flexing then you can normally get away with a high grade enamel and flex agent. You must still prepare the part by cleaning and scuffing the surface but since the etch agent won’t be compatible with your paint I would skip this step and then use a very light tack coat to get good adhesion.
Again I would only do this on a stable part that needs a specialty color applied to it that can’t be matched due to metallics or other paint features.