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Thread: Dry time before sanding base coat?

  1. #1
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    Default Dry time before sanding base coat?

    I shot some base coat this morning and I have a couple areas that need attention. I know it has to be dry, but wondering if there is a time span that
    the base needs to dry before I can do some light sanding and re-coat? I know that it needs to be re-coated before 24 hours.

    Thanks

  2. #2
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    Quote Originally Posted by kcode View Post
    I shot some base coat this morning and I have a couple areas that need attention. I know it has to be dry, but wondering if there is a time span that
    the base needs to dry before I can do some light sanding and re-coat? I know that it needs to be re-coated before 24 hours.

    Thanks
    It depends on the type of base and the type of chemicals that were added to it AND the temperature during the dry/cure cycle.

    If you're using a base that is only base and reducer and you used a "fast" reducer and the temperature is above 75 degrees you should be able to sand it 4 or 5 hours after it's sprayed. If you can heat the panel with a lamp (or in the sun) you can probably cut that time in half.

    Base can have a tendency to be gummy and clogs the paper quickly so sometimes wet sanding is best. Sometimes it's best to sand it as early as possible because some base coat products will tend to wrinkle if they are re-sprayed after it dries too long.

  3. #3
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    Quote Originally Posted by kcode View Post
    I shot some base coat this morning and I have a couple areas that need attention. I know it has to be dry, but wondering if there is a time span that
    the base needs to dry before I can do some light sanding and re-coat? I know that it needs to be re-coated before 24 hours.

    Thanks
    You need to read the tech sheet, what paint are you using. there are a number of basecoats that have strict warnings DO NOT SAND the base.

    Oh boy did I start a firestorm on another site on this subject! LOL A few years ago people were suggesting to sand the base, I gave the same warning, they blew me off. I went out and did a little test and the base and or clear would come RIGHT OFF with tape after it was done! I mean EVERYWHERE the tape was it pulled off EVERY square MM of clear or base off depending on when I sanded it. So you want to keep the sanding to a minimum "de-nib" is how it was referred, do NOT sand it flat! Now, if you have to, you simply keep this to the smallest possible area.

    Brian

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    The problem I had was a little lifting. I let it dry and then knocked it down by wetsanding it, and then shot a little sealer primer over it. I will wetsand with 400 again in those areas. My goal is to shot with base again and then clear. My window is about 20 hours now.

    I read the data sheet already and it just says dry in 15 min and tape free in 60 min. It seemed to sand fine by wet sanding.

    It's Deltron DBC

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    Quote Originally Posted by kcode View Post
    The problem I had was a little lifting. I let it dry and then knocked it down by wetsanding it, and then shot a little sealer primer over it. I will wetsand with 400 again in those areas. My goal is to shot with base again and then clear. My window is about 20 hours now.

    I read the data sheet already and it just says dry in 15 min and tape free in 60 min. It seemed to sand fine by wet sanding.

    It's Deltron DBC
    You should be ok if you can apply new base without lifting but Brian is right, applying clear over sanded base could cause problems if the base is past its recoat window.

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    I think it should be ok. I will apply new base over the whole car, so I am also thinking it should be fine............If I finish within the next 20 hr. lol Thanks

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    Quote Originally Posted by Len View Post
    You should be ok if you can apply new base without lifting but Brian is right, applying clear over sanded base could cause problems if the base is past its recoat window.
    Len, the test I did was with Dupont Chroma base and it FAILED no matter what I sanded and applied over it. If the base was sanded and more base applied then clear, the second coat of base and clear peeled off that sanded first coat. If the base was sanded and cleared the clear peeled off. If I sanded it but not as much, it still peeled just not as much, I am not kidding you it opened my eyes!

    You can skip from about the fifth page to about three from the end as all that you will find there is bickering. But honestly, until one of the guys who disagreed with me at the beginning did the test him self and was man enough to post the findings did it come to a somewhat peaceful end. http://www.hotrodders.com/forum/inte...on-110339.html

    Brian

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    Default I failed reading comprehension...

    Quote Originally Posted by MARTINSR View Post
    Len, the test I did was with Dupont Chroma base and it FAILED no matter what I sanded and applied over it. If the base was sanded and more base applied then clear, the second coat of base and clear peeled off that sanded first coat. If the base was sanded and cleared the clear peeled off. If I sanded it but not as much, it still peeled just not as much, I am not kidding you it opened my eyes!

    You can skip from about the fifth page to about three from the end as all that you will find there is bickering. But honestly, until one of the guys who disagreed with me at the beginning did the test him self and was man enough to post the findings did it come to a somewhat peaceful end. http://www.hotrodders.com/forum/inte...on-110339.html

    Brian
    Ok, let me get this straight.... You sanded the base while it was still within the recoat window, applied more base then cleared it and allowed it to harden. Then you applied tape to the clear and pulled it off and you also pulled off the clear and base with it. Is that correct?

  9. #9
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    Quote Originally Posted by kcode View Post
    The problem I had was a little lifting. I let it dry and then knocked it down by wetsanding it, and then shot a little sealer primer over it. I will wetsand with 400 again in those areas. My goal is to shot with base again and then clear. My window is about 20 hours now.

    I read the data sheet already and it just says dry in 15 min and tape free in 60 min. It seemed to sand fine by wet sanding.

    It's Deltron DBC
    I don't know Deltron so just follow the tech sheet and you will be fine. If it says "light sanding" or something like that take it seriously, do as they say. If it's a catalyzed base you can do about anything to it.

    Brian

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    Quote Originally Posted by Len View Post
    Ok, let me get this straight.... You sanded the base while it was still within the recoat window, applied more base then cleared it and allowed it to harden. Then you applied tape to the clear and pulled it off and you also pulled off the clear and base with it. Is that correct?
    Yep

    Brian

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    Quote Originally Posted by MARTINSR View Post
    Yep

    Brian
    I've got to try that with Glasurit to see what happens. I'm not a fan of DuPont paint so I don't use it if I have a choice and I don't think I've ever sanded Glasurit base but now you got me curious.

    What do you do if you screw up the base? Clear it, sand it and reshoot the base and clear?

  12. #12
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    Quote Originally Posted by Len View Post
    I've got to try that with Glasurit to see what happens. I'm not a fan of DuPont paint so I don't use it if I have a choice and I don't think I've ever sanded Glasurit base but now you got me curious.

    What do you do if you screw up the base? Clear it, sand it and reshoot the base and clear?
    You probably have nothing to think about with the Glasurit because they don't tell you in the tech sheets in bolt print as it is here DON'T SAND THE BASECOAT like it did in the Chromabase tech sheet.

    With the ones that have the warning, if you had a run or something and only sanded that one area, you were taking a chance. But if you were to do it you have to keep it to a as small an area as you possibly can. Sorry about that link, it was a serious battle over that subject, it looks like a discussion in the "fight club". LOL But like I said it sure was nice that Bob who disagreed with me did the test and posted the results, he is a gentleman.

    Brian

  13. #13
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    I will try to do a little test myself and see what it does? If did not say "DON"T SAND" anywhere as far as I could tell?

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    What's your opinion on spraying at about 26 hours when it says to respray within 24?

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    Quote Originally Posted by kcode View Post
    What's your opinion on spraying at about 26 hours when it says to respray within 24?
    You could have adhesion problems. I usually try to spray a couple hours after the base is applied but it all depends on your paint products.

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