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Thread: The how to's to painting plastic parts interior or exterior

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    The how to's to painting plastic parts interior or exterior

    I thought that I would post this up for those of you that would like to try painting your parts or have thought about having someone else paint your parts.

    Here is my advise:

    (1) Don't trust any bodyshop to prepare them for ya like I would if they are not accustomed to doing custom work because most bodyshops are mass repair shops and there 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.

    (2) If you spray it yourself, the types of spray paint that you can buy over the counter is the one's in the can but remember you may never find paints to match the color coded paints of your car unless you order them on-line www.paintscratch.com or you know a paint shop (Jobber) that will mix to code and sells them in a aerosol application. Sometimes you get lucky after several cans of paint to come up with someting close enough to your color, but even then if its not exact it will look odd. Sometimes you cannot predict by how the aerosol spray sprays out the paint that when it hits the surface the paint seems not to flow and gloss like expected especially if it is a solid color. Today most can spray applications have a clear paint that you can spray over the color for more shine and gloss. but remember most spray can paints are not meant for outside applications, the are not as durable as pro paints and are not UV protected by the sun from fading or yellowing. In my opinion spray can paints are good for interior applications only.

    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 5 draw backs to using aerosol spray paints. A. You can't always find a place to order or mix the paint in that application to your exact color code. B. It will not flow and gloss like automotive paints will. C. It is not as durable and long lasting as automotive paints, some brands are better then others for your particular application. D. the are not UV protected by the outside elements. E. The cured product dries soft and scrathes easy because the clearcoats do not have a cataliezed hardener added like pro paints do.

    The most important thing to do before any painting is involved is preparation, and in this case we are talking about any plastic, fiberglass or urathane part that is hard and not easily bendable like dash parts, outside mirrors, cowls, fibreglass parts bumper ect.... Either way you go as far as spray can VS pro automotive paints the preparation is the same and the paint you choose depends on the particular part and application. Here is what I do.

    1. Buy some good mechanics hand soap (The kind with the grit in it) and some double ott #00 steal wool pads, the larger the pad the better. Using a lot of water get the part completly wet and taking the steal wool and dipping it in the hand soap scrubb the part very thoughly and make sure to get every crevise and corner. Rinse well and let dry in the sun, after drying you can see any spots that you may have missed and re-do scrubbing with the materials and let dry again 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. This method works well with OEM textured valances and interior plastic parts.

    Special Note:--------------------------------------------------------

    A lot of our 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 example: Back window surrounds and most of the popular interior parts are a harder plastics like the dash parts, door switch bezels, overhead consoles, interior 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.

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    If you choose to sand the harder plastics with 80 grit, sand down the texture till flat (Test first a small spot) then sand with 150 followed by 220 and primer with a good flexable automotive primer as usual. Allow dry overnight and spray a mist of black can spray paint to mist on a check coat. Wet sand with 400 grit wet/dry sandpaper using water at all times to rinse off residue and make sanding easier. Sand till all the black check coat sands off but try to be careful not to sand through the primer back down to the plastic as you will have to re-primer that spot. Paint as usual.


    EXTRA NOTE: On interior hard plastic parts you can use the bulldog spraycans of flexable primers but "DO NOT" use the professional version of bulldog on dash parts as per the instructions. The interiors get hot during the summer seasons and the bulldog that is bought at your local paint jobbers do something weird. It is best to just primer your parts after sanding directly with the bulldog mixed with the primer instead of spraying the bulldog straight as directed on the container. The instructions say's to spray 2-3 coats on bare or freshly sanded plastic parts. During extreme heat in the interior of a vehicle the bulldog liquifies and bubbles under the primers causing a extreme mess and lifting of the primer/paint away from the part. I have found out that the professional version of Bulldog works best on exterior parts when sprayed by itself as instructed on urathane bumpers and all urathane parts/aftermarket plastics ect... applying the product by the instructions it is "NOT" meant for interior applications. It does not say so but by my experiance it won't work.
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    On new flat (No texture) urathance bumper, valances and all aftermarket urathane parts you should use 400 grit wet/dry sandpaper using water. Use the same procedures by rinsing and letting it dry to see where you missed spots. In very tight corners you can use the steal wool and handsoap as well.

    2. 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.

    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 and depending on how many parts you have you may need 3-4 cans. 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 let dry 2-3 minutes on the last coat and then it's ready for the primer as it needs to be sprayed wet on wet so dont wait long after the last coat of promotor to start spraying your primer otherwise you will have to sand the surface before applying your first coat of primer. 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. Anything you don't use you can return for a refund (Unused can).


    NOTE:
    For OEM parts that have a texture if you plan to allow the look of the texture show in your painted parts as long as you cleaned then using the mechanics soap and steal wool technique you need not primer.

    If you are going for a smoothed flat (Texture removed) finish the a flexable primer is nessessary.



    After your primers are dry (Preferrable over night) If your going to allow the texture on your OEM parts to show through your paint(For parts that have the OEM texture) then your need not sand it smooth , purchace a scuff pad (resembles a scouring dish pad) but 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 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, wash it down with water to rinse all dust, dirts, hairs, ect... and let dry. Try not to touch the paintable surface with your fingers because you have natural oils on your hands that will ruin your paints and paints have a tendency to separate from an oily spots, they call fish eye's

    If you are going for a flat smooth finish with no textures showing through you should spray a check coat first, this is a technique that helps you wetsand your part completely by visually seeing a change. Get a can of any black spray paint and spray a mist layer of paint from 9-15 inches away from your part and spray mist layers all around the primered part till you see thousands of tiny spots on the surface. Let the check coat dry for a few hours in the sun then when it dosen't feel sticky and feels dry Your ready to sand the primered surface, sand with wet/dry 400 grit sand paper using water at all times. You will see the check coat being sanded and will rinse off with the water letting you know that the surface is completely sanded in that area. Any left over spots of the check coat will indicate that area or spot has not been sanded, once all the check coat seems 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 or deep scratch. This same technique spraying a check coat is used in bodywork repairs after primering to assure a smooth flat surface before top coating (Painting). After sanding rinse with water and let dry to see how far you have sanded and repeat if nessassary. . Additional coats of primer is nessessary to build up the surface to hide the texture if you sand through then repeat with a check coat and sand again after drying.

    Up-date 9/6/04: 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 clearcoats for added flexability but according to the 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 1-3 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 way, 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 do not have proffessional equiptment for spraying pro auto paints.

    Spray can paints can be hard to obtain the kinds of results that make the paints gloss, you must make sure that you start off with a light even coat, let dry 15-20 minutes and do a second wetter even coat. Wait 15-20 minutes and follow with a 3 or 4 very wet coat and make sure to make it even coats all around or enough for even coverage. For a shinnier finish on solid or metallic colors you should also follow with a clear coat. 2 light coats followed by 1 wet coats letting dry 15-20 minutes between coats. followed by the last wet coat as desired.

    FINAL NOTE: If you have a pro paint it be sure to prepare it as instructed above to insure that what ever 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 mention that you want flex additives added to the primers, and all paint stages to be sprayed on your parts and get it in writting. This will help in your warrenty and protect you from having them (The paint shop) deny your claim.

    Good luck and if you have any questions email me direct.

    Stevet
    securitydog1@verizon.net

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    Thanks a million for the above write-up, Steve. IMHO, this is STICKY-worthy.

    Will be getting in touch with you when I am ready to paint-to-match the tailgate handle/surround of my L (YN silver)

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    Nice Stevet

    I got to get with you too. Have some painting that I need as well.

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    Definetly sticky this motha...

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    STICKY!

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    I STICKY that

    Tuned by Patrick @ PSI Motorsports 585hp & 609tq @ 15psi

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    Thanks! What a great thread.

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    Great Info Steve!!

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