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Thread: Hood advice

  1. #16
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    Dec 2015
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    Quote Originally Posted by S-C View Post
    Curious of this mottling you speak of.

    Do you find it is the metallic settling in and magnifying the left behind scratches, or random splotchy patches throughout the entire panel?

    Generally speaking, spraying your base to wet and not allowing enough flash time in between can cause this.
    S-C

    I took it as metallic settling in the scratches when he skip from 120 to 600, good question for clarification

  2. #17
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    I've always described mottling as dark and light spots in a metallic paint that was applied unevenly. When the paint is applied wet the metallic particles tend to sink in the color causing it to be darker then if applied more dry. After the application of the metallic color you may want to apply a light mist coat (drop coat) to even out the color and eliminate the mottling.

  3. #18
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    Dec 2015
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    Quote Originally Posted by bmarler View Post
    i don't have personal experience with that primer, but i have used similar. i don't like to use an over-reduced primer for sealer, it doesn't seem to give that super thin-glass like surface that dedicated sealers do. but if you like and use it with good results, then ok.
    the mottling is usually a result of the base being too wet/heavy so when the drop coat is applied it sinks in instead of laying on top and evening out the flake. the timing is everything, it needs to be just right so it doesn't sink in too far and add to the problem. if i'm going to do three coats of base i'll let the second one flash for quite a while, then do the last coat medium wet and follow right away with the drop coat. let that firm up pretty well before clear.
    Marler is right on the money as usual and gives you the advice you need. Silver metallics are just tough to apply, period. This same surface problem comes up often, especially with the lighter silvers. Look through the threads and you will see it numerous times. I use a dedicated sealer on most of my paint jobs but there are times I will use PPG DPLF primer (over reduced) for a sealer, the P sheet even allows for this. It just depends on the color and product I am applying. However, on silver metallics I always use a dedicated sealer PPG DASXX, as silvers are prone to what you are experiencing. When applying metallic silvers I slow way down on surface prep to make sure everything is dead on and no steps skipped. I especially pay close attention to my base application with every stroke of the gun. When drop coating, that is fast and furious, you still have to maintain that DTP and an even coverage, all the while making sure your metallic stays stirred in your guns reservoir. I start bc on silvers with a light to medium coat (adjust hand speed) followed by a solid medium coat after 15-20 minute flash time, check panel for coverage and extend my flash off time for up to 20-30 minutes prior to drop coat (booth at 70-72 F) too make sure metallic does not sink.
    To be honest Jim I don't think your going to be happy leaving the hood in that condition when the rest of your car meets your approval and I can almost guarantee you will experience die back in those scratch marks down the road as going from 120 to 600 is just too much. As bmarler stated "slow down and enjoy the process"

  4. #19
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    Jan 2019
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    Ontario Canada
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    Default Rushing

    Yes, rushing was the root problem, I have neglected getting equipment ready (excavating business) because I wanted to get this hood painted (last big piece) before the Mosquito's invaded the shop, This week we had a cold front move through so I took advantage of the weather window. Otherwise I would have to wait until November to paint it.
    On a positive note, I got it fairly strait and clear is smooth. will update on the shrink back later this summer.
    Jim

  5. #20
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    Dec 2015
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    Quote Originally Posted by JMTC View Post
    Yes, rushing was the root problem, I have neglected getting equipment ready (excavating business) because I wanted to get this hood painted (last big piece) before the Mosquito's invaded the shop, This week we had a cold front move through so I took advantage of the weather window. Otherwise I would have to wait until November to paint it.
    On a positive note, I got it fairly strait and clear is smooth. will update on the shrink back later this summer.
    Jim
    Jim,

    Just remember you can adjust your reducer to your temps when the time comes. I have painted in all kinds of environments long before I had a controlled booth. It might take some out of the box thinking but it is always possible. Good luck with your project.

  6. #21
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    Sep 2020
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    Quote Originally Posted by JMTC View Post
    On a positive note, I got it fairly strait and clear is smooth.
    Glad to hear your ok with the results.

    Quote Originally Posted by Ronf View Post
    I start bc on silvers with a light to medium coat (adjust hand speed) followed by a solid medium coat after 15-20 minute flash time, check panel for coverage and extend my flash off time for up to 20-30 minutes prior to drop coat (booth at 70-72 F) too make sure metallic does not sink.
    I think this is great advice, not only for silver, but all metallic.

    Quote Originally Posted by Ronf View Post
    Just remember you can adjust your reducer to your temps when the time comes. I have painted in all kinds of environments long before I had a controlled booth. It might take some out of the box thinking but it is always possible. Good luck with your project.
    Keep in mind Ronf is a seasoned custom painter (and a very good one), he sticks to using the same products, (high-end products too I might add) and for a good reason. He is very knowledgeable and knows how to mix them properly according to his booths environment. When he steps into the paint booth he is confident, knows what to expect from the product he’s using and has developed a unique spraying technique for both the application at hand and also for the characteristic of the booths environment cross drafts etc.

    Quote Originally Posted by Ronf View Post
    It might take some out of the box thinking
    This is more good advice and what all of us must do each time we attempt to spray something specifically in a non controlled environment. It is very important to study the conditions in which we are attempting to spray. Remember, the TDS is simply a guide for mixing & using the product under ideal/specific conditions. Many of us DIY hobby painters will never be able to paint in such “perfect” conditions. Even after weighing all the variables and attempting to mix the paint accordingly it is imperative to watch and study how the first few passes go down. This is when the (“It might take some out of the box thinking”) tweaking begins. Readjusting gun settings, air pressure, speed, adding more or less reducer, and the list goes on and on.

    For us unfortunate, each time we attempt to spray in a non perfect environment it’s like spraying for the very first time, it is unpredictable and will most likely always need some type of tweaking.

  7. #22
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    Jan 2019
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    Ontario Canada
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    Thanks for that s-c, This is only my second paint job, I have lots of practical experience to acquire!!
    The Camaro I did last year has tiger stripes down the hood and the average person can't notice them unless I point them out, Its shiny and that's what people see. So I did improve this time with minor mottling.
    I think next time I spray metallic on a hood I will stand it on a 45 deg so I can start at the top and work down, my furnace fan exhaust system can't pull overspray away fast enough when it lays flat, I think may be part of the problem also. Obviously cutting corners and rushing is what I did wrong the most.
    Thanks for caring everyone!!
    Jim

  8. #23
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    Nov 2013
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    olympia,wa
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    Quote Originally Posted by JMTC View Post
    Yes, rushing was the root problem, I have neglected getting equipment ready (excavating business) because I wanted to get this hood painted (last big piece) before the Mosquito's invaded the shop, This week we had a cold front move through so I took advantage of the weather window. Otherwise I would have to wait until November to paint it.
    On a positive note, I got it fairly strait and clear is smooth. will update on the shrink back later this summer.
    Jim
    if insects are a problem try to figure out how to do a positive pressure spray area. filtering the incoming air and maintaining positive pressure will keep most of the flying insects out. i still keep the tweezers handy, but rarely have to remove a winged critter. i used to get them all, flies, mosquitos, MOTHS...
    b marler

  9. #24
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    Nov 2005
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    Quote Originally Posted by bmarler View Post
    if insects are a problem try to figure out how to do a positive pressure spray area. filtering the incoming air and maintaining positive pressure will keep most of the flying insects out. i still keep the tweezers handy, but rarely have to remove a winged critter. i used to get them all, flies, mosquitos, MOTHS...
    Our shop is in the woods and during warm weather insects can be quite invasive. We keep the shop closed as much as possible and we cover the car we're painting then fog the paint bay and leave it overnight and also fog all around the shop to minimize the chance of a problem.

  10. #25
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    Nov 2013
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    Quote Originally Posted by Len View Post
    Our shop is in the woods and during warm weather insects can be quite invasive. We keep the shop closed as much as possible and we cover the car we're painting then fog the paint bay and leave it overnight and also fog all around the shop to minimize the chance of a problem.
    fogging is a good idea. don't know why i never thought of that.
    b marler

  11. #26
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    Quote Originally Posted by bmarler View Post
    fogging is a good idea. don't know why i never thought of that.
    Just be sure to cover the car because the fog is usually an oil that will cause problems with the paint.

  12. #27
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    Sep 2020
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    Quote Originally Posted by JMTC View Post
    The Camaro I did last year has tiger stripes down the hood
    Just as Len stated above in post 17, “metallic paint that was applied unevenly”. This is basically it in a nutshell.

    I’m wondering if you’re having these issues (tiger stripes/mottling) due to improper gun adjustment/wrong tip size while shooting your base coat.

    Make sure your gun is clean & adjusted properly; Len has put out a great video on gun set-up, check it out here:

    Spray Gun Adjustments Video

    If your gun is not shooting properly it will definitely screw you up all over the place.

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