What grit should I sand plastic to before primer?

How to paint the interior plastic of a car

kike_gsi8v27-12-07, 01:04bearing in mind that the biggest relationship with the paint was to paint the brake calipers, I am a little green in these things and wanted to know the steps to follow when painting a piece, in this case of plastic but for fins, doors or other tips would also be welcome.

i want to paint a fender and a grill. for amateur finish, how many grains of sandpaper and which ones should i use? after sanding and cleaning, do i have to apply primer? is it specific for plastic? do i have to sand afterwards? how long is the drying time between primer and paint? how many coats of paint?

Apocalypse_88827-12-07, 14:22First, sand with a P80, then with a P150, to finish with a P240 (more or less, it can be 80-120-180, 80-150-220, etc…but start, always start with P80, and try not to skip more than three levels when changing sandpaper).

xujuanmi27-12-07, 14:34 if you are going to sand plastic never sand with less than 240 because you will skip pieces and scratch it a lot, for sanding sheet metal I always start with 120. there are many types of primer 1 component 2 component spray gun to spray, if you’re going to throw a spray takes to dry little alomejo a half hour at most, if a gun put 2 oras, always give 2 manosdeimprimimacion and etre hand and hand wait for the solvents evaporate then sand with 400 dry, and 1200 water and paint, the hands asta that you cover well pntura, which are necessary, greetings

Adhesion promoter for plastics

One of the previous steps that condition the quality of any welding process is to know how to clean and prepare the surfaces to be welded. The objective of this step is to eliminate any impurities that could lead to a defective joint.

The first of these, although it may seem obvious, is that plastic should not be treated as if it were wood (which is the material most often associated with the sanding process) as it can be more easily damaged. It should also be noted that the usual thickness of the plastics we handle (e.g. PVC pipes) does not leave much room for error, so it is important to be especially careful.

In order to have full control over the plastic sanding process, it is advisable to do it with sandpaper directly by hand (avoiding sanding machines or files) or attached to a wooden block.

The grain determines the abrasion capacity of a sandpaper and the smaller it is, the rougher the surface will be (for example 40-50 very coarse, 60-80 coarse, 100-120 medium, 150-180 fine and 240-400 very fine).


The diversity of materials used in the manufacture of a vehicle imposes the need to know new repair techniques, tools and products. The various types of adhesion promoters and primers are products that have become indispensable in the body shop, as they offer an effective solution to the problem of adhesion on certain substrates.

Adhesion promoters and primers are an adjunct to paint that is always used on a bare substrate that does not have good adhesion and is subsequently to be coated, sealed or painted.

The materials present on the vehicle with this peculiarity are plastics, aluminum and glass (and its silkscreen printing), although adhesion enhancers should also be used on bare steel. Therefore, when working on one of these substrates, it is necessary to apply a specific adhesion promoter or primer to ensure adhesion, unless the product to be applied is self-adhesive.

How to paint a new plastic facia

Sandpaper is used in the automotive repair process when sanding the surfaces of an automobile to apply paint. A body sandpaper serves as an essential tool for polishing, smoothing, and removing any errors from the vehicle’s surface.

When the oxidized portion of a body panel has been sanded with a piece of 32 or 40 grit sandpaper, 150 grit is an ideal choice for smoothing out irregular grooves that might exist in certain spots.

This type of 320 grit, is ideal for smooth dampening and for removing thick paint. With a piece of 320 grit sandpaper, the paint should come off the vehicle with evenly applied disc strokes.

When working with 320 grit on the paint, the shine of the metal should sparkle the surface. Because of the strength of the sandpaper, it is a good choice for cars or trucks that have been treated with enamel or other hard coatings.

Before applying the new paint job, you’ll want to sand off the older blue coats. With 320 grit, the blue should come off smoothly and easily. Once all the layers have been removed, the surfaces should be smooth enough for a primer coat of the new paint.