Preparing plastic parts for paint int/ext.

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Old 11-08-2005, 11:37 AM
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Preparing plastic parts for paint int/ext.

For the DIYS or if you have someone else paint it for ya!

Here is my advise:

(A) Don't trust any bodyshop to prepare them for ya unless they are a custome shop because their only intent is to get the job done a.s.a.p and because of that they may not clean, sand and prep them as good as it should, so I will explain ways you can guarentee that what ever paint is sprayed it will stick.

(B) If your a DIYS painter, spray can paints bought over the counter don't always give you a good choice to find the color to match your car unless you order them on-line or you know a paint shop (Jobber) that will mix to code and sells them in a aerosol application. And try to purchace your color and cleacoat of all the same brand.


You do have 2 choises, try painting it yourself using spray can paints or have a pro paint it for ya using automotive paints. There is 3 draw backs to using aerosol spray paints. You can't always find a place to purchase or mix the paint in that application to your exact color code. It may not flow and gloss like pro auto paints will. It also is not as durable and long lasting as pro paints.


The most important thing to do before any painting is involved is the preparation of the part prior to primering and painting.

1. For soft, rubbery parts, like OEM front lower valances & upper pads, interior grab handles ect....Buy some good mechanics hand soap (The kind with the gritty pumice in it) and some double ott #00 steal wool pads. Using a lot of water get the part completly wet, take the steal wool and dip it in the hand soap & scrubb the part very thoughly and make sure to get every crevise and corner. Rinse well and let dry, after drying the part will look dull indicating a sanded surface, any spots that you have missed re-do scrubbing and repeat the process and check. The hand soap and steal wool serves 2 purposes the hand soap washes and get's all grime, oil, dirt & bugs off the parts and rinses well while sanding the surface very fine without damaging or fraying the plastic, and the steal wool does exactly the same assuring fine sanding of the surface. You may also use scuff pads.

Special Note for that smoothed look:---------------------------------------

A lot of Ford plastic parts that have texture have different charactaristics in the compounds in the plastics where you can sand the texture off with 80 grit sandpaper. For expl: Back window surrounds and most of the popular interior parts are hard plastics like the dash parts, door switch bezels, overhead consoles, exterior door handles, back tailgate handles ect..., where the plactic of a lower OEM valance are soft. The harder plastics can be sanded with 80 grit where as the soft plastics will fray, this is where you would use the steal wool & soap method only on the soft plastic parts.

EXTRA NOTE: On hard interior plastic parts you can use the bulldog spraycans of flexable primers but "DO NOT" use the professional version of bulldog on interior parts as per the instructions, the interiors get hot during the summer and the bulldog fails. It is best to just primer your sanded parts directly with the bulldog mixed with the primer instead of spraying the bulldog straight as directed on the container. During extreme heat in the interior of a vehicle the bulldog liquifies and bubbles under the primers causing bubbling and lifting of the primer/paint away from the part. The professional version of Bulldog is specifically intended for exterior parts only when used as instructed on urathane bumpers and all urathane parts/aftermarket plastics ect...


If you choose to sand the harder plastics with 80 grit, sand down the texture till flat then sand with 150 and 220 and primer as usual. For that smoothed finish you may primer up to 3-4 coats. Let dry for at least 24 hours so that the primer will shrink,and then apply a check coat. Get a can of black spray can paint or primer an spray a 1 coat mist layer of paint 12-15 inches away from your part and all around the primered part till you see thousands of tiny spots on the surface. Let the check coat dry for a few hours or when it dosen't feel sticky and is dry. Once dry your ready to sand, this is a technique that helps you wetsand completely by visually seeing a change.


Use wet/dry 400 grit sand paper using water at all times. Rinsing often you will see the check coat being sanded off letting indicating the surface is is being sanded. Any left over spots of the check coat will indicate that area or spot has not been sanded, once all the check coat gone this will indicate a completely sanded surface, this will also show you low spots that may need to be repaired or re-primered to build up that low spot, deep scratch or sand through. After sanding rinse with water and let dry to see how far you have sanded and repeat if nessassary.


If you want to have the texture of the part to show through the paint use only the soap and steal wool technique to clean and sand the part and primer only a few light coats and let dry. Do not sand smooth purchace a scuff pad (resembles a scouring dish pad) it's made to scuff paints and primers. There is red and grey, I prefer the grey because it sands lighter then the red. After scuffing the surface lightly trying not to scuff through the primer, and watch out for the edges otherwise you can sand through and you'd have to re-primer in those spots again. Wash down with water to rinse dust, dirts, ect... and let dry. Try not to touch the paintable surface with your fingers because you have natural oils on your hands that can be left on the paintable surface.


On new (No texture) urathance bumper, valances and all aftermarket urathane parts you should sand with 400 grit wet/dry sandpaper using water or sand dry with a scuff pad. Use the same procedures by rinsing and letting dry to see where you missed spots. In very tight corners you can use the steal wool and handsoap as well. Once you see that every nook and cranny has been scrubbed and sanded, once rinsed and dryed it will look hazy and dull and is ready for primer.

2. At this stage if you want to paint it yourself you will need a few things that can be bought at Autozone & Pep boys and some automotive paint store's. They have a special flexable primer promotor at $5 a can, purchase only what you need. The same with the primers of the same brand but make sure they say flexable primers for plastic parts. Spray the promotor first as directed letting tack dry according to the instructions between coats folllowed by your flexable primer as instructed. Sweep side to side slightly overlapping the prior coats edge and don't stop in one spot without releasing the spray button for it will build up and run.


For semi professional painters that have the equiptment and experience, I have always used Bulldog Flex/tiecoat/Flex additive in all of my primers, paints and sometimes the clearcoats for added flexability, but according to my instructions for these types of modifications especially on interior plastic parts I do not recommend spraying pre-coats of the Bulldog on the freshley sanded surfaces as I had instructed above in the topic "Extra Note"

What is important to note here is that especially flexable parts must be sanded smooth and flat not to rely on the use of the primer build up technique to hide the texture as it will not matter how much flex additive you put into your primer mixture it is bound to crack from the slightest bend. So the trick here is to assure a flat sanded surface first and make sure the freyed plastic hairs are to it's minimum applying only 1-2 coats of primer, so when you apply your check coat and wet sand with 400 grit or above you end up with a thin coat of primer on the surface minumizing the chance of cracking due to excessive layers of primer build up.

Then you are ready for painting. Make sure that where you are painting there is no wind present to blow dust in your paint job and if you are painting outside in the drive wayor in a garage, water down the driveway to keep the dust and lint down. Best weather conditions to spray would be around 65-75 degress. This description is for those who either will use spray can paints or pro paints.

Spray can paints, you must make sure that you start off with 2 light even coat, letting tack dry according to instructions. Follow with a 3 or 4 very wet coat and make sure to make it even coats all around or enough for even coverage letting tack dry between coats. For a shinnier finish on solid or metallic colors you could also follow with a clear coat. 2 light coats letting tack dry between coats, followed by the last wet coat as desired.

FINAL NOTE: If you have a pro paint your parts for ya be sure to prepare it as instructed above to insure that what ever primer or paints they spray it will stick. You do not at this point have to purchase any paints or primers they will do that. But make sure to ask for flex additives added to the primers, and all paint stages to be sprayed on your parts and get it in writting (On the estimate). This will help in your warrenty and protect you from having them (The paint shop) deny your claim.

Good luck
 
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Old 11-10-2005, 08:20 AM
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Hey Securitydog - welcome to FTE.

Great post.
 
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Old 11-17-2005, 08:44 PM
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Good deal, and one more note, this looks soooooo much better and usually costs less than buying those stick-on dash kits. In the past 2 days I painted the part of the dash that is around the radio, the part that is around the guage cluster and the light switch and the part right under the guage cluster, and also the glove box handle and vent on that side also. I painted them the same color of the truck(charcoal). I work at a body shop so I was purdy lucky, I did all the work myself so it ended up costing my $15, and that was just for the paint. I cleaned off the plastic parts and then sanded them with 400grit sandpaper(didn't mind about the texture), then I sprayed the primer on them, let dry, sanded with 800grit sandpaper, tacked all the parts then shot with the color coat, then I added 2 coats of clear, these pieces shine great and give the interior the look I was looking for. btw, about the vents, you notice in many custom jobs people do, and in the kits you can buy, they don't paint or make a piece for the vents, which imo, looks like crap. all you have to do is take the vents off and the part you paint just pops off and you can paint it, and it makes ALL the difference, to me atleast. i'm thinking about painting a few more pieces in my truck, i wanna get some pics up soon for ya'll.
 
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