Krylon Spray Paint Problem

Discussion in 'Low Power Rocketry (LPR)' started by Michael MacDonald, May 4, 2019.

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  1. May 4, 2019 #1

    Michael MacDonald

    Michael MacDonald

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    I just finished painting an Estes Sky Raider rocket that was started in 1977. After priming the rocket with Kilz and sanding to a smooth surface I applied several light coats of Krylon ColorMaster Gloss Black to the nose cone. The finish was flawless; smooth and shiny. After 3 days of drying I decided to add a couple of coats of Krylon ColorMaster Gloss Clear to the whole rocket to cover the decals and add a finishing touch to the build.

    I followed the directions carefully and put on 3 or 4 light coats of the clear, about 2/3 of the nose cone finish started to wrinkle. The other 1/3 looks fine.

    I'm a seasoned painter. I've never seen this happen before. The rest of the rocket has no paint flaws, just the nose cone.

    Of course I can sand the problem off and then re-prime and paint. But I'm curious why this might have happened.

    Any ideas?

    Thanks for your replies
     
  2. May 4, 2019 #2

    Michael MacDonald

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  3. May 5, 2019 #3

    Bufkin Fairchild

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    I had the same happen with krylon clear. I don't think my color coat was fully cured.
     
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  4. May 5, 2019 #4

    GlenP

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    I get the same thing occasionally with the Rusto2x, really have not been predictable enough for me to figure out why, but it does tend to repeat itself. Might be that temps or humidity do not allow the paint to fully cure, a night time lower temperature does not contribute to the curing process as much as during a warmer temp in the day. So, double the time in days if you are still having colder nights. Just one idea of what might be a contributing factor. If you can still smell the paint, it has not cured enough for an overcoat.
     
  5. May 5, 2019 #5

    Bruiser

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    Paint adhesion to plastic is problematic. First you need a paint that says it will work with plastic. You really need to pay special attention to surface prep with scuffing/sanding cleaning prior to coating. Lastly, it's always a good idea to wait, and then wait even longer before you apply anything over the paint. Even the same color once you've gone past the initial recoat window.

    Just what I've learned so far...

    -Bob
     
  6. May 5, 2019 #6

    James Harechmak

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    I think it's something in the air or a reformulation of most paints found in Walmart and auto parts stores. I've noticed that you've got about an hour to recoat colours and after that they need a full 7 day cure for more colour or top coats. I've had no crazing trouble with Tamiya rattle cans, rattle cans made by the local auto body supply house or ones made by online suppliers like automotivetouchup.
     
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  7. May 5, 2019 #7

    SammyD

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    I've used Krlyon for years to paint my rockets, but NEVER have I used Kilz for the priming. My $.02 worth:

    The nosecones of many LP rockets are plastic that emit formaldehyde. Paint doesn't like formaldehyde. Before painting my plastic nosecones, I wash them with soap and water, dry them, sand them (about 320 or 400 grit), and sometimes even put an "adhesion promoter" on the plastic (adhesion promoter is made to assist with painting plastic trim on automobiles with the adhesion promoter going on the plastic first). Then prime following the directions on the promoter can.

    My theory is that the formaldehyde in the plastic never let the primer coat fully cure. When you put a topcoat on an undercoat that isn't cured, you can get results like your photos show. I've had it happen too. Where I usually see it is when I've failed to let a product like "Spot Putty" fully cure, then have gone over it with primer (which seems to be able to handle the uncured putty), then a paint topcoat, only to find the paint isn't going to allow the putty to get away with being uncured like the primer did.

    I'd start with getting the nosecone cleaned up and properly prepped for paint, and I think you'll find you get the results you're looking for. Finally, why Kilz primer? I'm curious...
     
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  8. May 5, 2019 #8

    SammyD

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    By the way, I had that Sky Raider kit as a kid, kept it into adulthood, then about 10 years ago, my nephew ended up with some rockets to fly. Of course, I had to go blow the dust off the Sky Raider which hadn't flown in some 30 years, but she soared like she always had on a big D-12-7. Unfortunately, after a few packs of motors, she drifted into the trees way up a mountain side never to be seen again...... :-(
     
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  9. May 5, 2019 #9

    Michael MacDonald

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    I like using Kilz because it goes on evenly, covers imperfections and grain and sands to a smooth, non glare finish. It receives paint easily, making it a great primer.
     
  10. May 5, 2019 #10

    Michael MacDonald

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    The Sky Raider nose plastic nose cone was purchased in 1977 and has sat unfinished for all these years. I suspect that any residual formaldehyde had escaped or stabilized in that time.

    The black gloss coat didn't wrinkle after sitting for 48 hours. It was only when I applied the clear coat that the wrinkling occurred. And the clearcoat on the body tube and basswood fins didn't wrinkle either.

    After the above comments I suspect that the paint on the plastic should have been left to cure a week or two before the clear coat.

    I will redo the nose cone but wait a few weeks before the final clear coat application.
     
  11. May 5, 2019 #11

    SammyD

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    I'm glad to hear it works well for you. I would have never thought to use Kilz... :)
     
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  12. May 5, 2019 #12

    Michael MacDonald

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    I sense your skepticism but I suggest you give it a try. It sands to a beautiful flat finish
    base and covers up a lot of minor grain imperfections and spirals on LPRs.
     
  13. May 5, 2019 #13

    SammyD

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    I use sandable primer that's made for that very thing, filling low spots and imperfections. I'm good, but that might also be where some of your paint compatibility issues are coming from. That it's just on the nosecone tells me it's the chemicals in the plastic, but it might be incompatibility in the paints too...
     
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  14. May 5, 2019 #14

    Michael MacDonald

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    No to belabor the point, but if your theory were correct, that would have happened with the Krylon Black Gloss. It didn't.

    It happened only when the clear Krylon was applied over the black. Someone else mentioned that they had a similar problem with the Krylon clear.

    This makes me draw a different conclusion; I should have waited much longer than 48 hours for the black to completely cure. ( like the idea that someone posted about waiting until there is NO smell of paint.)

    I'll put that theory to test when I redo the nose cone and post an epilogue.

    But in the future I will follow your advice about washing and prepping the plastic nosecone more thoroughly.
     
  15. May 5, 2019 #15

    Curtis Enlow

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    The wrinkling is odd; I think that is a formulation issue. In fact, i seem to remember something about actually using dissimilar paints to get the wrinkling as an effect on purpose...

    But, adhesion on plastics is a problem. I refinished a very old plastic case for a Honda two-stroke outboard once, taking great care to scrub, sand, primer, wet-sand, repeat endlessly and final coat with gloss enamel. It's looked awesome! And the first time it flexed...it all peeled right off.

    I went to the auto-parts store and bought some Dupli-color Adhesion Promoter for plastic bumpers, etc., for my nose cone. Their paints are pricey, but good quality and lay-down much nicer than rattle-can hardware store paints. Their primer is not 'high-build' but is smooth and flows nicely; Krylon primer feels rough and less adhered in comparison. Do a search on Dupli-Color here; lots of good info.
     
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  16. May 5, 2019 #16

    rcktnut

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    I say ditch the Krylon clear, the crap eats everything up. If you leave the color coat cure for a long time, at least a week it might be ok. I had an Estes Phoenix, painted it, applied the decals about 10 days later, and about 3 days after that used the clear coat to seal the decals. Every decal shriveled up,they looked like your nose cone, paint was fine. Had to order a set of decals, never used the crap again.
     
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  17. May 5, 2019 #17

    Michael MacDonald

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    Thanks! You echo another poster who also had problems with Krylon clear.

    I'm not going to use it again. I guess I have to find something else to hold the decals in place and give the finish a wet look.
     
  18. May 5, 2019 #18

    neil_w

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    On @hcmbanjo 's blog he has recounted that topcoats on plastic nose cones can sometimes take a loooooong time to cure. It would be consistent with your experience here: the nose cone paint didn't fully cure before the clear coat was applied.
     
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  19. May 19, 2019 #19

    yorn

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    Did you end up repainting the NC yet? I'm getting back into rocketry and I purchased a can of the Krylon Clear, so now this thread has me nervous about using it. I'm interested to know if the curing time was the culprit. I primed and then painted the base color on an Estes Patriot about two weeks ago and haven't had time to finish it up. I think after I apply the second (And last) color to it I will give it a week or two to cure before attempting to add the clear. I can certainly report back with my results if anyone is interested.
     
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  20. May 19, 2019 #20

    Curtis Enlow

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    You might want to check out a search here on using acrylic floor polish. I know fine scale modelers have been using it for years with great success, and it's easier and less toxic to use and, as an added plus, can be touched up easily when scuffed. I have an airbrush and am seriously considering it.
     
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  21. May 19, 2019 #21

    Michael MacDonald

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    Not yet. I've been letting the paint set for a month before I try to redue it. There have been some good suggestions here, like washing the NC well first. I'll repaint with the same Krylon gloss black and that sit for at least 1 month before attempting a clear coat. I have mixed feelings about using Krylon clear again. On one hand it makes sense to use a clear from the same company to minimize a chemical reaction due to different formulas. On the other hand, this combo did cause the problem in the first place. I will be sure to let the new black coat sit for at lease 1 month before applying the clear coat, no matter what brand I use. I'll report back with results either way.
     
  22. May 19, 2019 #22

    Michael MacDonald

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    Its been unclear as to which brand of floor polish to use since Futura has been renamed and/or changed so many times.
     
  23. May 19, 2019 #23

    neil_w

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    This is the current incarnation. They carry it at Ace I believe (at least, that's where I bought it a few years ago). It’s what I always use for gloss finish. For matte, I'm back to the Krylon UV-resistant spray.

    https://www.pledge.com/en-us/products/pledge-floor-gloss
    [​IMG]
     
    Last edited: May 19, 2019
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  24. May 19, 2019 #24

    BABAR

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    When in doubt, try it on a piece of similarly treated and painted scrap
     
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  25. May 19, 2019 #25

    Curtis Enlow

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    I got this at either Ace hardware or Wally World.

    [​IMG]
     
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  26. May 19, 2019 #26

    Michael MacDonald

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    Have you actually used this on a rocket?
     
  27. May 19, 2019 #27

    Banzai88

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    It's a staple of rocket painting, been proven for years. Use without fear. Note that the name and bottle changes frequently. 1 bottle, like 1 bale of barf, might be a lifetime supply.
     
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  28. May 19, 2019 #28

    Michael MacDonald

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    Thank you. The label changes are confusing but will try it after the repaint.
     
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  29. May 19, 2019 #29

    Curtis Enlow

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    I've used it on scale models and foam board R/C planes.

    Do a search here in TRF and there are threads on using it on rockets.

    Curtis
     
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  30. May 19, 2019 #30

    Curtis Enlow

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    As long as it is an acrylic-based floor polish it's good. In fact, it probably all comes out of the same factory ;)
     
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