Touching up metallic paint

Discussion in 'Bodywork' started by welland99, Oct 1, 2011.

  1. welland99

    welland99 Hardcore MB Enthusiast

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    I've got a few rusty spots I need to touch up. I've rubbed off the flaky paint and applied rust killer. Now for paint. The colour is metallic maroon.

    I have a jam jar of paint from the body shop. It was left over from the last proper paint job the car had.

    I've done a bit of testing on some scrap metal and it seems very fifficult to apply the metallic bits in the paint. Most of the time they stick to the brush and the result is non-metallic maroon. The only way to get the metallic bits to come off the brush is to blob it on very thick, which is a problem with vertical body panels.

    What can I do?

    Is proper touch up paint thicker and better at keeping the metallic bits in suspension?
     
  2. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    no! this is why you can always see the touch up... best advice is to shake it vigorously then apply the paint as quickly as possible.
     
  3. WOODYTHEWISE

    WOODYTHEWISE Hardcore MB Enthusiast

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    Hi, try shaking the jar as above, then pour a small amount into a small receptacle, I find the cap off almost anything,shaving foam,deodorant ect works best, just enough to cover the base. The base paint and particles are then easily picked up by the brush without overloading. Hope this help,John
     
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  4. OP
    OP
    welland99

    welland99 Hardcore MB Enthusiast

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    Hi Guys,
    Thanks for your advice. After my vigorous shaking the first time, there were lots of small bubbles like in a milk shake which floated to the top. It was like brushing on a kind of foam (in my test). :eek:

    The bubbles soon burst on my test piece, but then there was the problem of the paint being too thick and it was running off.

    Sounds like there's no perfect solution. :wallbash:

    Will the dried paint be a durable weather proof coating, or will I need to get some lacquer to brush over the top?
     
  5. CKLclive

    CKLclive Banned

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    Its base coat so will be needing clear coat over the top
     
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  6. donubenz

    donubenz Hardcore MB Enthusiast

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    Hi the paint the body shop give you for touching up with is next to useless without a spray gun. If its a standard colour you can maybe get a spray can from Halfords or sometimes an auto paint supplier can make one up for you. its never going to be perfect in match or quality but with a bit of care can look presentable till you need a professional spray job. Remember the first coat should be thin to act like a glue when its flashed off a bit. The following coats can be wetter but the distance from the surface affects the metallic effect. Thin and dry gives the most reflection. A thick coat allows the metallic bits to be vertical in the paint and gives a greater contrast when viewed from the side. this is why brushing gives such a poor match as the paint is too thick. Don't forget the clear coat spray.
     
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  7. OP
    OP
    welland99

    welland99 Hardcore MB Enthusiast

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    There's so much I do not know about painting!

    What's the difference between the paint used in spray guns and the paint in touch up bottles (in laymans terms)?

    Do the touch up kits need a clear coat on the top as well, or are they a different kind of paint that does not need a clear coat?
     
  8. donubenz

    donubenz Hardcore MB Enthusiast

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    Ok without getting too deep its all about the thinners used to dilute the paint so that it can be atomised for spraying.Because of green issues manufacturers use water based paint and usually it is "charged" electrically to attach to the car body and baked on. Single solid colour or metallic base and both generally have a clear transparent coat, always on metallics as polishing will remove the flakes and alter the appearance otherwise.
    Commercial re finishers, unless they are a big company, use paints that have various plastics in them using a thinner with a poisonous iso cyanide content.They have to use air fed masks for H/S reasons and the paint is made to flow and harden in bake ovens.
    Prior to this cellulose paint was used that could air dry. This is like nail polish and what the MB touch up kits basically are. Supplied with one paint tube and one clear lacquer. As the name suggest only really for small spots and stone chips.
    The Halfords sprays will have a cellulose type based air drying carrier and recommend using in a well ventilated area.
    The development of paints is interesting if somewhat boring!
    Cellulose was developed after WW1 to use the cellulose supplies from gun cotton when a surplus was left after the war when someone found a solvent to dissolve it.
    Acrylic was similarly developed after WW2 to use all the plastics left over from air craft canopies.
    So that is why your paint is next to useless unless the guy sprayed with "celly" and that is unlikely as it is illegal because of organic solvents now!
    Remember like all good jobs the hard work is done before the final visible coat which is just the icing on the cake. Rust treatment, feathering edges, primer coating and lots of work with abrasives are needed to get a suitable base to paint on. Also you need compatible paints or they will peel and blister so sometimes a barrier coat is used under the primer.
    Don't let me put you off, a painted surface to protect rusty metal is far better than none even if it is not to the original standard!
    Don
     
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  9. Dieselman

    Dieselman Banned

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    Fantastic information donubenz.
     

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