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Thread: The advantages and disadvantages of catalyzing basecoat

  1. #1

    Default The advantages and disadvantages of catalyzing basecoat

    Since you folks here seem to be a great source of information backed by long experience, I hope you don't mind if I keep picking your brains on this stuff...

    I've heard differing opinions on whether or not to catalyze basecoat, as the theory is that catalyzing the clear is sufficient to do the job. However, having read here in a few posts the recommendation to catalyze it when using it underhood or near potential fuel spills, that makes me believe that not catalyzing the base may result in a less resilient paint job long term.

    My local paint supplier tells me not to catalyze base, and that they have never had issues with anyone saying they had issues, so long as they are following proper procedures otherwise.

    So what say you all? I am of the opinion that I want to do every step of the process the RIGHT way, do not want to take any shortcuts at all that may affect the final product. Is not catalyzing the base a shortcut, or well accepted industry standard with no disadvantages?

    Thanks again.

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    Default Well...

    Quote Originally Posted by PaintEmIfYouGotEm View Post
    Since you folks here seem to be a great source of information backed by long experience, I hope you don't mind if I keep picking your brains on this stuff...

    I've heard differing opinions on whether or not to catalyze basecoat, as the theory is that catalyzing the clear is sufficient to do the job. However, having read here in a few posts the recommendation to catalyze it when using it underhood or near potential fuel spills, that makes me believe that not catalyzing the base may result in a less resilient paint job long term.

    My local paint supplier tells me not to catalyze base, and that they have never had issues with anyone saying they had issues, so long as they are following proper procedures otherwise.

    So what say you all? I am of the opinion that I want to do every step of the process the RIGHT way, do not want to take any shortcuts at all that may affect the final product. Is not catalyzing the base a shortcut, or well accepted industry standard with no disadvantages?

    Thanks again.
    There are but a handful of paint manufacturers that catalyze base but think about it. I think your concerns of the base are needless because the hardened clear is your protection. I mean, figure it this way. Are all primers & sealers catalyzed, do they need to be? Then, look at how good catalyzed clearcoat looks and holds up over many years compared with enamels or lacquers.
    Listen, know that I'm NOT criticizing what your point is. I just think you might be overthinking the base coat thing. Auto manufacturers don't do it and they have the most to lose. By all means, if you think you need or want it, you would have to seek out a brand that requires it.

    The other thing is, if cheap no name lower quality products were used, you might get some adverse effects down the road. If you have any products you consider that produce problems later on, please share them. Share ANYTHING you think of because you're on a forum where your concerns are taken very seriously by all the other members here. Enjoy your weekend.

    Henry

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    I don't catalyze base and the only advantage that I'm aware of is that if you have to repair the paint after the clear is applied and you sand through the clear and need to apply more base and clear then the uncatalyzed base can tend to absorb solvent from the new base causing the clear to lift at the edge of the sand through.

    If you're using a "good" base coat paint and you sand through the clear you can apply some clear to seal the repair, allow the clear to harden then sand it lightly and apply your base and clear to top off the repair. This takes a little longer but eliminates the need to catalyze the base.

    The trick is to use good quality materials to start with, don't go for the cheap stuff if possible.

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    Quote Originally Posted by Len View Post
    I don't catalyze base and the only advantage that I'm aware of is that if you have to repair the paint after the clear is applied and you sand through the clear and need to apply more base and clear then the uncatalyzed base can tend to absorb solvent from the new base causing the clear to lift at the edge of the sand through.

    If you're using a "good" base coat paint and you sand through the clear you can apply some clear to seal the repair, allow the clear to harden then sand it lightly and apply your base and clear to top off the repair. This takes a little longer but eliminates the need to catalyze the base.

    The trick is to use good quality materials to start with, don't go for the cheap stuff if possible.
    Len,

    This has me curious. Do you never catalyze the base for engine compartments? It's not unusual for me too do a build with a 600-700+ hp motor, esp. when building an old school engine with a 671 blower and large tube headers which produce a lot of heat. Well over a decade ago my jobber advise me to start using a base hardner due to the amount of heat produced in these engine compartments. I do remember him stating other advantages but my memory sure isn't what it used to be. Your thoughts?

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    Quote Originally Posted by Ronf View Post
    Len,

    This has me curious. Do you never catalyze the base for engine compartments? It's not unusual for me too do a build with a 600-700+ hp motor, esp. when building an old school engine with a 671 blower and large tube headers which produce a lot of heat. Well over a decade ago my jobber advise me to start using a base hardner due to the amount of heat produced in these engine compartments. I do remember him stating other advantages but my memory sure isn't what it used to be. Your thoughts?
    In the many years I've been spraying base/clear finishes I've never used hardener in base for engine compartments. I've done some experiments with it a few years ago but nothing in engine compartments. However my high-end spraying is done using Glasurit and even my daily spraying is done using Diamont both are BASF products. I've done several engine compartments and have not had any problems. We've done several show cars that are driven occasionally and the engine compartments haven't shown any ill effects.

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    I have never heard of using a basecoat hardener because it somehow helps in high heat areas. I personally don't think it would make any difference either way.

    The advantage of using a basecoat hardener is as previously stated -- if you cut through the new clear into a basecoat that didn't use hardener then there is a better than 50/50 chance that if you try to spot in/blend new basecoat in that cut through area the unhardened base will lift like you applied paint stripper. And not just when the paint is fresh, it could happen years later when you're repairing a collision damage panel that the basecoat had no hardener.

    Always a good idea to use basecoat hardener.

    the ONLY DISadvantage to using a basecoat hardener is the cost of the hardener.

    Also keep in mind that a lot of basecoats are not designed to be used with a basecoat hardener.

    PPG DBU was designed specifically for using a basecoat hardener.

    PPG DBC is designed to be used either way - no hardener or you can add PPG DX-57 hardener.

  7. #7

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    Yes, Catalyze your base 5%, you can use the hardener you will use in your clear if you like.

    The idea of catalyzing basecoat is like this

    Catalyzed urethane sealer
    Catalyzed basecoat = doing this enables that base to cross link with the sealer and clear
    Catalyzed Clear

    auto manufactures do not use the same stuff we use out here in the collision world, their clear does not even contain catalyst. its more like a powder coat. has to be baked around 450 degrees to dry it.

  8. #8

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    This is why I like having discussions on topics like this.. even in this thread I'm getting different answers.

    One thing I am not interested in doing is duplicating the OEMs and their compromise paint jobs. The large majority of OEM paint jobs that I have seen in the base/clear era do not last reliably beyond 10-12 years, and I don't consider that acceptable if someone is paying real money for a quality paint job.

    Now, I also understand they use compromise materials, and don't apply any more clear than they have to. So we're not comparing apples to apples when comparing a typical OEM paint job to a $15k custom job.

    What I was told by my local paint supplier (who has been in business for more than four decades under the same owner) was that I do not need to catalyze any basecoat, regardless of whether or not the manufacturer specifies, so long as I will be spraying clear on top well within the recoat window. The explanation given to me was that the hardener in the clear hardens the base as well and helps the clear bond to it better than if the base was catalyzed as well. I'm not sure I understand how it would bond *better* this way, but again they did say they have never seen it cause any issues in practice. As such, I have sprayed basically all of my base/clear jobs without catalyzing the base, and have not yet seen any issues myself.. however, none of these paint jobs are more than a few years old yet, so there hasn't been enough time passage to really know how well they will hold up in the long run.

    I know that any paint job, even a cheap one, will last much longer with proper care, but I have to assume that my customers will not be taking proper care of their paint as I would mine, so I want to make sure I provide a product that will still last as long as possible even if it is neglected.

    As such, if catalyzing the base helps extend the life of a given paint job, there is no question that I would always want to do so. The cost of the hardener is simply a non-issue in the scope of a multi-thousand dollar paint job.

    There remains one question.. catalyzing the base obviously dramatically shortens the recoat time for it.. is the reason why some of you aren't catalyzing your base due to the time constraints this imposes on your spraying process?

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    Like I previously stated we don't catalyze our base and it has nothing to do with time constraints. We apply our base wait about an hour at 70 degrees then apply our clear and if we did catalyze the base we would do exactly the same thing.

  10. #10

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    Quote Originally Posted by Len View Post
    Like I previously stated we don't catalyze our base and it has nothing to do with time constraints. We apply our base wait about an hour at 70 degrees then apply our clear and if we did catalyze the base we would do exactly the same thing.
    Ok.. so, for my clarification's sake.. is the reason that you don't catalyze your base simply because it isn't necessary? Or is there some specific disadvantage to catalyzing it?

    Edit: and a question/point I forgot to ask earlier.. given the specific mix ratios that all of these products call for, is the specified hardener ratio in the clear adequate to properly catalyze the base as well, or do you increase the amount of hardener in the clear by some amount to make up for the lack of hardener in the base?

  11. #11
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    Quote Originally Posted by PaintEmIfYouGotEm View Post
    Ok.. so, for my clarification's sake.. is the reason that you don't catalyze your base simply because it isn't necessary? Or is there some specific disadvantage to catalyzing it?

    Edit: and a question/point I forgot to ask earlier.. given the specific mix ratios that all of these products call for, is the specified hardener ratio in the clear adequate to properly catalyze the base as well, or do you increase the amount of hardener in the clear by some amount to make up for the lack of hardener in the base?
    Different paint products need different mixes, the products I use don't have to be catalyzed.

    If you think you want to use hardener in the base you need to read the technical data sheet for the paint you're using so that you know what hardener to use and how much is in the mix. For the products I use the base hardener is different than the clear hardener.

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    Quote Originally Posted by PaintEmIfYouGotEm View Post
    Ok.. so, for my clarification's sake.. is the reason that you don't catalyze your base simply because it isn't necessary? Or is there some specific disadvantage to catalyzing it?

    Edit: and a question/point I forgot to ask earlier.. given the specific mix ratios that all of these products call for, is the specified hardener ratio in the clear adequate to properly catalyze the base as well, or do you increase the amount of hardener in the clear by some amount to make up for the lack of hardener in the base?
    The chemical make up of the basecoat and the clearcoat are not the same. PPG's DBU uses an "activator" as opposed to a hardener. I do not believe that adding clear coat activator to a basecoat is a good idea. I personally have never and would never do that. I have read where using a correct hardener for basecoats aid adhesion and durability. I don't believe that either.

    Basecoats are basically solvent evaporation based paints. So technically they never dry or cure. (unless you use a hardener/activator). Solvent based paints used for many years was lacquer. It dried through evaporation of the solvents (mostly lacquer thinner). What I'm getting at is lacquer never really dried or cured to the point that it would not absorb more lacquer thinning if sprayed on top of it. In other works if you painted a fender in lacquer and 10 years later you have to do a minor collision repair on that fender. The new paint WILL eat into and be partially absorbed by the 10 year old lacquer paint. Current unhardened basecoats are basically the same thing (I don't believe they are lacquer based) but they WILL lift (sometimes) if new basecoat is sprayed over it it. Especially where you cut through the basecoat leaving an open edge.

    Like I said earlier, the only advantage to using a basecoat activator/hardener is you are guaranteed that the basecoat won't lift (like you applied paint stripper) in a repair days, months or years down the road. I usually used PPG DBU with activator for any collision repair jobs I did just so that I knew if I had to work on that same car later I knew the basecoat would not lift when applying new basecoat. When you do this kind of work for a living time is money and screwing around with basecoat lifting from a previous job can be a time consuming pain in the ass that ends up costing you money with time wasted.

  13. #13

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    Quote Originally Posted by Phil V View Post
    The chemical make up of the basecoat and the clearcoat are not the same. PPG's DBU uses an "activator" as opposed to a hardener. I do not believe that adding clear coat activator to a basecoat is a good idea. I personally have never and would never do that. I have read where using a correct hardener for basecoats aid adhesion and durability. I don't believe that either.

    Basecoats are basically solvent evaporation based paints. So technically they never dry or cure. (unless you use a hardener/activator). Solvent based paints used for many years was lacquer. It dried through evaporation of the solvents (mostly lacquer thinner). What I'm getting at is lacquer never really dried or cured to the point that it would not absorb more lacquer thinning if sprayed on top of it. In other works if you painted a fender in lacquer and 10 years later you have to do a minor collision repair on that fender. The new paint WILL eat into and be partially absorbed by the 10 year old lacquer paint. Current unhardened basecoats are basically the same thing (I don't believe they are lacquer based) but they WILL lift (sometimes) if new basecoat is sprayed over it it. Especially where you cut through the basecoat leaving an open edge.

    Like I said earlier, the only advantage to using a basecoat activator/hardener is you are guaranteed that the basecoat won't lift (like you applied paint stripper) in a repair days, months or years down the road. I usually used PPG DBU with activator for any collision repair jobs I did just so that I knew if I had to work on that same car later I knew the basecoat would not lift when applying new basecoat. When you do this kind of work for a living time is money and screwing around with basecoat lifting from a previous job can be a time consuming pain in the ass that ends up costing you money with time wasted.
    I understand that activator and hardener are not the same, and I did not suggest adding clear coat hardener to base coat. I asked if adding more hardener to the clear would make up for a lack of it in the base.

    So, given what several folks have said about base coats lifting during collision repairs later, why *wouldn't* you catalyze your basecoat to make sure you don't have to worry about that later?

    And given your description, that base never fully cures without activator, would it not stand to reason than a paint job done with activated base would be tougher and more resilient than an otherwise identical paint job without activated base?

    Please understand, I'm not asking any of these to be argumentative, I'm asking so I understand the proper way to do all of this, and most importantly, why. Thus far I've seen mostly a consensus that catalyzing the base is not necessary, but doing do offers no disadvantage either. That leads me to the conclusion that I think I would prefer activating it. But if that's a bad idea, I want to know why.

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    One advantage of not putting hardener in base is you can dump excess in a mason jar and not have it go hard, then use it later if you are painting project a few pieces at a time over several months.

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    Quote Originally Posted by JMTC View Post
    One advantage of not putting hardener in base is you can dump excess in a mason jar and not have it go hard, then use it later if you are painting project a few pieces at a time over several months.
    Good point, I forgot about the fact of being able to use the paint later if it's catalyzed/activated.

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