Spray painting a fuel cap

Discussion in 'Car and Van Talk' started by Iron_Mike, Feb 22, 2018.

  1. Iron_Mike

    Iron_Mike Active Member


    I managed to knock off my fuel cap.

    I got a replacement and fitted it. However it came unpainted.

    I have the spray paint and the lacquer. However I don't have the plastic primer yet.

    As the car is grey, should I be getting a grey primer? As it is a primer wasn't sure if I should stick with a clear primer ?

    In regards to the order of spraying :

    Primer - Then leave 24 hours

    Spray paint - Then leave 24 hours


    Focusing on building up the coats slowly and completing the work when it sunny and dry.

    Just wanted to check my approach was correct.


  2. If using rattle cans then the above is ok for a small item, with a couple of comments I might add.

    Definitely grey primer, possibly acrylic, dependds on the type of plastic.

    Then avoid damp and cold at all costs. That's not easy at this time of year.
    Iron_Mike likes this.
  3. Longy75

    Longy75 Member

    So long as your primer is lighter than your final colour you should be ok, this is how I resprayed my motorbike

    Primer 2 - 3 light coats left for a couple of days then rubbed down with 600 wet and dry
    Base coat 2 - 3 light coats, left for a couple of days then rubbed down with 1000 grit wet and dry, can do one pass with 600 but be careful as it's easy to rub through especially at the edges
    Clear coat 2 - 3 light coats, left for a couple of days then 2 passes with each 1000, 1500, 2000 wet and dry
    Then 3-4 passes with rubbing compound, followed by polishing compound then your usual polish.

    Your looking for light even coverage throughout the spraying and not to get a wet look.

    Hope this helps
    Iron_Mike likes this.
  4. Is your car metallic, Mike?

    But, essentially, yes, that's the order. You should also get some 1200 grit wet or dry paper (that's very fine) to clean and key the supplied finish in case it has manufacturer's release agent or stuff on it.

    (Can you check whether your new cap is already 'primed'? It might be, and that would save you some work.)

    Ok, assuming it does need priming, give the cap a going-over with the 1200 grit and a little water. Get it fully 'matt' and clean. Dry with a lint-free cloth.

    Shake shake shake the primer. Make sure the cap is 'warm' - ie not at outdoor temps. Spray the primer on in horizontal passes, each overlapping t'other by a good third. Turn the cap thro' 90o and repeat.

    Ok, this is the important bit with all the coats you apply - you need to constantly observe and monitor and judge and adjust the application of the paints at all times. You want the applied coats to be thick enough to level out, but not so thick as to run. And not as light as to look 'dusty' or 'sandy' or 'matt' (when wet).

    The primer coat ain't important, 'cos you'll be 1200-gritting that anyway before the paint coat, but the primer will give you a good idea of how well you applied the paint.

    Allow to fully dry - this can be as quick as a half-hour if the capo is warm and in sunshine, for instance. But best to give it longer to be sure.

    Anyhoo, the surface should look completely smooth and flat. Once you wet or dry it (wet...), you'll see that the surface wasn't as perfect as it appeared - the sanding will firstly flatten off the paint 'peaks' that you didn't realise existed. Once wet or dried, you'll then see a perfectly flat surface - so perfectly flat and smooth it almost has a shine to it! If you don;t do this before the main paint coat, it'll never be an excellent finish.

    Ok, now for the 'paint' coat - the most important. This is where you do need to observe and judge and adjust. If you follow the manufacturer's instructions - hold 8 to 12" away? - then chances are you'll end up with a 'dusty'-looking finish (orange peel). You want to apply the coats until they 'flow' together, but not enough to risk causing runs or bands. I usually fire from around 6" or so, closer than they recommend.

    With a small item like a cap, this should be easy; lay it so's the surface is flat and horizontal, and start you paint 'passes'. Press trigger before the can gets to the surface and release once it's passed - swish. Go back in t'opposite direction - press-swish-release. If it's looking too 'dusty', then it ain't thick enough, so slow down. Once covered, if the finish hasn't 'flowed' together to a lovely smooth level glossy finish, then rotate the cap 90o and give it passes at right angles, this time making sure it has flowed together. NEVER spray stationary - always in passes.

    Once you are happy that the paint has been applied evenly, allow to dry. If you've made a few passes to get this coating, then fair chance the paint is thick enough for lacquering, but if you want to apply more paint, then you may get away with repeating the above after a half hour.

    Allow to fully dry, and then lacquer. Some may suggest 1200 gritting before the lacquer, but if it's metallic this might not be a good idea.

    You can build up numerous coats of lacquer, allowing each one to go 'off', and this will allow you to give it all a final cut and polish if needed. Hopefully it won't be needed, tho', provided you have made each coat 'flow'.
    Iron_Mike likes this.
  5. Iron_Mike

    Iron_Mike Active Member

    Cheers DA that is really helpful.

    It is a metallic paint, so definitely need the lacquer.

    Will give it my best shot.
  6. Kingscurate

    Kingscurate Member

    A tip to judge how the paint is drying between coats: piece of cardboard or even white masking tape next to job you are spraying, as each coat is applied and drying, touch the cardboard with a fingertip, if fingertip is wet then leave a few minutes. You are looking so your fingertip touches paint and it feels tacky. this is so your not putting your hands all over the job to see if another coat is done
    Another thing most of the rubbing down between primer/gloss/lacquer is to give a key, scotch brite can be used for this.
    Cleanliness of the job and paint application are your main tools here
    Iron_Mike likes this.
  7. Iron_Mike

    Iron_Mike Active Member

    Great advice. Thanks guys.

    All I need now is the weather to warm up.

    Looks like I will be waiting until April :(
  8. Yup - if you try this when it's cold - say below, I dunno, 14-ish degrees? - then you will likely suffer from 'bloom'.

    The paint's solvents evaporate very quickly, and this has the effect of rapidly cooling the item - so you'll get moisture condensing on it. Not a pretty sight.
  9. HarDeBloodyHarHar

    HarDeBloodyHarHar Active Member

    Can't you fit a temporary one, and spray the cap indoors/shed?

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