Cross linking lacquer question

Discussion in 'Finely Finished' started by Matei, Dec 11, 2019.

  1. Matei

    Matei TDPRI Member

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    Hi Guys!

    I recently finished a strat build which received several coats of sanding sealer (nitro based sealer from Bondex)

    The guitar is at the moment level sanded (completely dull, no lowspots) at P 400 grit and waiting for the clear coats.

    I am planning to use a HVLP gun to apply the clear coat, which should be high gloss nitro based.

    I went to my local paint shop and asked them for a clear, nitro based, for application on musical instruments, and I mentioned that the wood is already sealed...

    I got the recommendation to use one of their products, nitro based, designed for wood. Bought it and went home. The datasheet specifies the following:

    - It mentions that is a 1K product
    - It mentions that it is cross linking
    - It specifies that one should apply a base layer, wait 2 hours, scuff with P 320 sand paper and apply top layer. All the same product

    Now the surprising part:
    - It says that recoating should occur within 48h from the time when the basecoat was applied in order to avoid lifting up.

    My questions:
    1. I was planning to do 6 - 8 coats of clear on this instrument. Can I still use this product? Like 2 - 3 coats 2h apart day 1; 2 - 3 coats 2h apart day2; 2 - 3 coats 2 h apart day 3 or am I risking this "lifting up" mentioned in the documentation?

    2. What if I decide to leave the guitar for let's say 5 days and then add new coats? Would that be possible?

    3. Wasn't nitro based clear supposed to melt into itself? Why do they explicitly say to sand between coats?

    4. Do you think there will be incompatibility issues between the sealer and the clearcoat?

    It is relatively hard to get more info from the manufacturer's website, and the guys from the paint shop are facing a kind of blockage when they hear about "musical instruments", so any advice based on your experience would be appreciated.

    Regards,
    Matei
     
  2. Dacious

    Dacious Poster Extraordinaire

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    Nitro keeps outgassing. If you do it within two days there's no problem. The new coat melts into the previous.

    So coat <48 hours recoat <48 hours recoat etc

    You shouldn't be wet sanding unless you get a blooper.

    Once a coat has dried > 48 hours you risk the next coat lifting - you'd need to coloursand it.

    1k complicates things. It'll be harder and thicker most likely. If you get 2-3 good coats on I'd leave it at that personally.
     
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  3. eallen

    eallen Tele-Afflicted Silver Supporter

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    What they gave you isn't nitro. I shoot Sherwin Williams LOVOC nitro continuously and have shot a ton of other brands. You can recoat within 20 minutes, 60 minutes, if done right, 8 hours, 24 hours, 2 days, 2 years.

    If you pile it on you will be waiting because piling more on before adequate time will trap solvents. Do multiple 3 pass light coats and you are done in no time.

    You never need to sand nitro before applying another coat no matter how long.

    Post the actual product name and type they gave you.



    Eric
     
  4. Drak

    Drak Tele-Holic

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    The word cross-linker is all you need to know.

    Yes, it's not the lacquer you 'want' it to be.
    You're getting thrown hard simply because it has the word lacquer in it.
    In your case, act like the word lacquer isn't even in it, just forget it.
    It will apply differently.
    It will dry differently.
    It will buff out differently.
    You Need to wear a Real mask.
    And you better damn well know how to clean a gun out, for real-sies.
    That product doesn't re-melt for easy cleanup/cleanout.
    It Does Not Re-Melt.Once it's dry, it's dry, period.
    That's why they're giving you the re-apply time schedule.
    If you don't clean the gun Like A Pro, your gun is trashed.

    There's nothing wrong with the product if you're a finisher and you know what you have and how to use it.
    In your case, it ain't even close, take it back.
     
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  5. Peegoo

    Peegoo Tele-Holic

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    I agree with Drak.

    There are too many question marks to keep you in your comfort zone. It's probably an LT-70 acrylic lacquer and not nitrocellulose lacquer.

    Take it back.
     
  6. Matei

    Matei TDPRI Member

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    Hi,

    Thank you for your replies :) it is really helpful.
    After digging a bit deeper I found the English version of the datasheet. The company is not producing in English speaking countries, I think it is actually somewhere in the German speaking region.

    Just a small side note: in German the term "lack" defines any paint, including the colored ones, while the term "klarlack" defines clear coats. The English version, which has some translation hiccups, describes the product as "nitro-clear varnish"

    Here is the English datasheet: https://www.adler-coatings.com/Canto/tmb/soloplast-stq_tmb_1611_en.pdf
    Here is the German datasheet: https://www.adler-lacke.com/Canto/tmb/soloplast-stq_tmb_1611_de.pdf

    Regards,
    Matei
     
  7. Matei

    Matei TDPRI Member

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  8. Vizcaster

    Vizcaster Poster Extraordinaire

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    Generally when the instructions on a finish material provide a recoat window, it's a sign that the material has a limited ability to burn into the last coat. If you wait too long you'd need to scuff sand to get mechanical adhesion. What surprises me is the warning that waiting too long can 'lift' the earlier coats, which sounds like there must be some pretty strong solvents in there. Either that, or after the product cures past the recoat window, it no longer allows the new coat to burn in and instead the solvent from the next coat starts to act like a paint stripper.

    Does the retailer have any guidance for you? In other words, some of the instructions might be very conservative and in actual experience with the product it might be okay to stretch the re-coat window by a bit??
     
  9. Matei

    Matei TDPRI Member

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    Hi, I am currently spraying the 3rd coat... let's see. The employee from there, which never let me down until now, ensured me that the product will do what I want it to do (spray multiple layers on multiple days) but emphasized the fact that I have to scuff between layers.

    We'll see how it goes. I'll keep you posted :)

    L.E.

    I think that the warning should be interpreted like this:
    - If applied over cross linked coat (more than 48 h) it needs mechanical adhesion to make sure that the new coat will not lift from the previous one.

    Anyways, on Monday, if wife is in good mood, we put it under IR microscope to see what's in there, if it really cross links and so on...
     
  10. Matei

    Matei TDPRI Member

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    It took 4 layers, all in all 3 and 1 with overnight break.
    I cleaned the gun "Like A Pro" as per @Drak 's advice, to avoid trashing.
    Also left my favorite Darth Vader mask at home and bought a Real mask, as instructed.

    Long story short, between the 3rd coat and the last one I scuffed sand with P 400 just to have my conscience clean.
    24 hours later almost does not smell like solvents anymore. Did a preliminary level sand and polish at the heel in a hidden place and results are promising but the whole thing is still a tad too soft for committing to the polish.

    I am going to give it another 48h and the finish the baby.

    The product is amazing, it lays super nicely in thick-ish layers, with amazing coverage. Though it REALLY runs hell if you push it too far.

    Final clear thickness ~0.32 mm measured on something that got peeled out from the painter's tape from the neck pocket.

    It is indeed nitro based, and that is what I needed to be able to bond with the sanding sealer.
    And indeed, it is missing the cellulose part. There is another polymer there, that one that cross links, probably by reacting with the humidity in the air.

    After 24 h, on my test piece it completely melted when rubbed with fresh nitro.

    Regards,
    Matei
     
  11. Vizcaster

    Vizcaster Poster Extraordinaire

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    I wonder how that peeled-off sample will shrink in thickness as it hardens. Let us know how things turn out.
     
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