Do you have to sand primer before painting plastic

Q: Can you paint straight over plastic primer?

Youll need to apply a coat of primer, preferably one that bonds well. This will help even out the surface of the plastic and give the paint something to stick to. The spray-on kind would be the easiest to use, but you can get the brush-on kind as well. Let the primer dry completely before proceeding.

Q: Can you paint over primer without sanding?

The highest quality bonding primers will often state no sanding is necessary and will adhere to almost any shiny surface, such as glass, metal, tile etc. Primers like Kilz, Fuse, and Zinnser are good for bonding very strongly. Primers can be costly, but if they are of good quality there will be no need for sanding.

12-08-2006, 08:55 AM #1
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apriliaforum Junkie

Painting plastics - sand the primer before applying???
I thought I'd ask since I've never painted plastics before. To sand the primer or not to sand, that is the question (well, one of them)...
If you do sand what grits do you use?
Do you apply more than one coat?
If so, do you sand between coats?
The benefits and disadvantages of clearcoating...
I figured with all the knowledge here it would be best to tap into it before doing
...
12-08-2006, 10:20 AM #2
apriliaforum Junkie

sanding
I have not painted in a while. if you call and auto paint store they will give you details
you would not want to sand with anything grittier than a 600 grit before final paint.
we used to use a green kitchen scratch pads for the final preparation of the surface before painting. any decent paint finish usually requires clearcoat. depend on what your painting with.
one thing I would get carried away with is putting the primer on too thick to try and cover up scratches. it would eventually dry internally and reveal the scratches again later. it is better to use several lighter coats and let them dry in between if you are covering up scratches.
hope this helps
12-08-2006, 10:36 AM #3
apriliaforum expert
Painting plastics
The primer next to plastic substrate definitely needs to be formulated for use on plastics. In our polyurethane paint we used a nitricellulose-base additive for good bonding to acrylic panels. So, leave the primer on unless you have a source to new plastics-compatible primer.
If you do need new primer, most body repair supplies shops have all you need since there is a lot of auto plastics refinishing done now.
12-08-2006, 11:52 AM #4
apriliaforum expert
you would not want to sand with anything grittier than a 600 grit before final paint.
I personally think that 600 is too fine and you will run into adhesion problems if you use it. I never final sand with anything finer than 400 wet sanding because of this and have had no problems that way.
Here is the write up I did when I painted my Katana. It may help you, it may not. Either way, if it helps, cool! If you go down to bare plastic, ensure you use a base plastic primer to assist adhesion as well. You can use other primer on top of that if need be, or use a polyester glazing putty to fill in scratches, but before spraying your color base coat, make sure you also use a sealer.
http://771doug.netfirms.com/Ron.html
12-08-2006, 12:06 PM #5
apriliaforum expert
Last bike I painted was my KLR.....I used mostly rattle can spray-on bedliner
I sand everything, but you'd be much better off asking JohnB (bikepaintr) than I guy like me!
Good luck, have fun.
Will
Last edited by VikNWill; 12-08-2006 at 12:10 PM.
"It ain't eazy bein' cheesy!"
12-09-2006, 11:11 AM #6

apriliaforum expert
Originally Posted by colo_heff
I thought I'd ask since I've never painted plastics before. To sand the primer or not to sand, that is the question (well, one of them)...
If you do sand what grits do you use?
Do you apply more than one coat?
If so, do you sand between coats?
The benefits and disadvantages of clearcoating...
I figured with all the knowledge here it would be best to tap into it before doing
...
If you are asking whether to wet sand the final layer of primer before painting the answer is definitely or you will have adhesion problems. Wetsand with 600grt with a few drops of dish detergent in the water for lubrication. Be sure to rinse well with clear water afterwards.
If you are painting with a base coat/ clearcoat system you only need enough coats of color to cover your primer & hide the 600 grt sanding scratches, usually 2 will suffice, then apply 2 to 3 wet coats of clear. If using a single stage color I apply 3 good coats to allow for wet sanding with 2000 grt & buffing.
John B.
02 Ash Black w/Staintunes, PC3 w/custom map, Evo Filter, Mille Air Boot, derestricted air box, Heli-Bars, Wilbers shock, new rectifier, Scottoiler, heated grips, T'meister, c/f frt. fender & hugger.

Do you sand primer on plastic?

Using a fine-grit sanding block, lightly sand the surface to a dull finish. This will provide some texture, so the primer will stick. After sanding, dust the surface using a dry brush (a large paintbrush works great!) to clear away the debris and wipe the surface with a wet cloth.

Can you paint straight over plastic primer?

You'll need to apply a coat of primer, preferably one that bonds well. This will help even out the surface of the plastic and give the paint something to stick to. The spray-on kind would be the easiest to use, but you can get the brush-on kind as well. Let the primer dry completely before proceeding.

Can you paint over primer without sanding?

The highest quality bonding primers will often state 'no sanding is necessary' and will adhere to almost any shiny surface, such as glass, metal, tile etc. Primers like Kilz, Fuse, and Zinnser are good for bonding very strongly. Primers can be costly, but if they are of good quality there will be no need for sanding.

How do you prime plastic before painting?

Using a spray primer and top coat formulated for plastics, prime the surface, let it dry, then paint it. Spray multiple light coats, letting them dry completely before applying each succeeding coat.