O.K. what's going on with my primer?

Discussion in 'General Modeling' started by Boba Flint, May 13, 2012.

  1. Boba Flint

    Boba Flint Sr Member RPF PREMIUM MEMBER

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    After all my years of model building I have never had this problem and it is happening with different brands, Krylon, Plasikote, Rustolium.

    I spray on some primer and when it dries it is not a smooth finish, it has a texture like sandpaper. I can sand it smooth but if I apply another coat the same thing happens. I managed to save a couple of projects but this is very irritating since it is happening everytime now.
  2. Contec

    Contec Master Member

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    have tried with another can? Could be something in just that can...
  3. Locry

    Locry Member

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    Maybe the weather has something to do with it? Maybe drying out too fast even before hitting the model?
  4. opal1970

    opal1970 Well-Known Member

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    maybe the CIA has something to do with it. :behave

    I am assuming you have tried different matiereals, I was having problems and I believe that the resin I was using was to blame. If you are priming cast parts, I have gone over to spraying the primer directly in the silicone mold, letting it dry and then pouring the resin. The resin attaches itself to the primer MUCH better than the primer to the resin. The coat of primer actually becomes the outer layer of the piece, meaning it will not even scratch off (unless you are sanding etc. of course).
    the only downs are:
    • It is a little bit messy till you get the hang of it
    • If you spray too much sometimes the resin in that area is deformed or bubbley
    • In the time between a dried coat of primer and pouring the Resin, the coat of primer can peel away from the silicone if you bend the silicone too much. This does not usually affect the cast but the flake of primer is then no longer on the surface of the part and rather underneath the surface, meaning that area is not primed
    • if you spray primer anywhere other than in the part area in a 2 part silicone mold, the silicone cannot seal against itself as normal and the seam is probably slightly larger and Resin can leak easier. For one sided molds this works absolutely fantastic.
    • CA glue does not work good with primed parts, so try to avoid spraying primer to parts of the mold that you intend to glue to something else later.

    I have been doing this on molds that will allow it for quite some time now and am very happy with the results, not only is the surface of the parts primed but they are as smooth as the mold itself and maybe it is just my imagination but I find that the fine details are even crisper than when pouring resin alone.

    I have tried this with paints other than primer i.e. in a 2 part mold, spraying primer on the half of the mold that is the outside of the peice and spraying Black (lightblocker) on the other silicone mold so that when the peice comes out it is primed on the outside and black on the inside. Well this works but I am not as happy with the results. I am continuing to test this but normal paint tends not to stick to the silicone as well and peels away.

    Hope that helps.
  5. ShowCraft

    ShowCraft Well-Known Member

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    This has happened to me too.
    The can spays fine, then spits out sandpaper grit. Then it sprays fine again later on :confused
    Several brands have done this.
  6. ralphee

    ralphee Sr Member

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    Ive had it happen with the UPOL too, intermittent "rough" spraying.

    Best i could do was really warm it up in hot water, and shake till my arm was pumped, id did cure it a bit, so it led me to think it was older stock in the store.

    It was almost as it, pinhead sized particles were leaving the nozzle, really odd.

    Ive had to switch brands AGAIN though as i cant put up with that in small high detail, and hear to reach areas of a model.

  7. moffeaton

    moffeaton Master Member RPF PREMIUM MEMBER

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    Upol too? crap. So what have you moved on to, Lee?

    I've noticed the "newer ergonimical" nozzles are crap, and spit paint more than they spray. I think i might buy a spray gun and be done with cans....
  8. ralphee

    ralphee Sr Member

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    It was just one can J, but even so, it bugged me.

    Ive moved back to Halfords own acrylic, to be fair, it does go on super smooth, and sprays very powerfully, giving a superb even mist, guess i only moved to UPOL since i had a few tack problems on a kit.

    Yes, these new nozzles are awful, they moved around too much as well, causing little drips from under the nozzle itself, annoying.

    A spray gun is tempting, but what brand of primer to throw in that :confused.

    Wish the powers that be (that are there for our safety lol) would leave things well alone.

  9. moffeaton

    moffeaton Master Member RPF PREMIUM MEMBER

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    Agreed! If I want cancer, let me get cancer! :p

    YES, the dripping is maddening.

    On the spray-yer-own... dunno, doing a little research on that!
  10. ralphee

    ralphee Sr Member

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    Im looking now, seems i can get the same 1K self etch in the UPOL tins, more volume, lower cost, bonus, once you bag a big tin of cutting thinners, your set for a while.

    Looking at spray guns now....gotta be honest, it looks the better option practically, and easier on the pocket overall.

  11. moffeaton

    moffeaton Master Member RPF PREMIUM MEMBER

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  12. Ghadrack

    Ghadrack Sr Member

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    I have similar issues occasionally based upon the air temperature, temperature of the paint and the item to be painted on a hot, high humidity humidity combination day.

    If I have the Air Conidtioning on in the house, and have my paint stored inside, and the figure/model parts in the house, then take them outside where it is significantly hotter and there is higher humidty when the spray primer hits the miniature / model part it gets that gritty sandpapery texture instead of a smooth finish.

    Letting the paint and parts sit in the same environment where you plan to do your priming so they are all about the same temperature might make a difference.

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