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Automotive paint hardener compatability

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Mike W.
Posts: 27517
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Automotive paint hardener compatability

Post by Mike W. »

Yeah. Something everyone runs into, I'm sure. :facepalm:

The Datsun has evil failing clearcoat. I dressed it up a tiny bit last year for vacation, but it's failing. No way I'm going to put paint on it that costs more than it's worth, but I am willing to burn a few bucks and hours to try to make it semi presentable.

Single stage paint seems like the winner for this, even thought the rest is base/clear. I've found a quart for under a hundred, but it needs reducer and hardener. I've got some from other paint projects, but not this brand, not this model etc. I'm looking for semi presentable, not a non hardening goo, nor wrinkle coat. So, the obvious question is is there any compatibility between different manufacturers products? I'm sure they'd say no, but they 1, want to sell their stuff, and 2, don't want to be on the hook if it turns ugly. 3, they might not even know, but I bet some of their chemists do, but they're not going to go there, understandably.

And I didn't even do well in HS chemistry, let alone on this level. I've looked at the spec sheets and they have some similarity, but not the same. And this is just what I have on hand, not what is recommended!


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But anyone have any idea? (and if I didn't already wear a respirator when using this stuff I damned well would now)
Shawn D.
Beamter
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Re: Automotive paint hardener compatability

Post by Shawn D. »

Why are you considering doing this? Do you already have the hardener or is it notably less expensive?
stuartinmn
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Joined: Feb 12, 2006 12:00 PM
Location: Minneapolis

Re: Automotive paint hardener compatability

Post by stuartinmn »

Most paint companies have a tech support line you can call with questions.  They may say what you have is not compatible, but on the other hand they may say it is - it won't cost anything to ask.

You may want to mention the names of the products you're considering using, there may be people here with first hand experience who can help.  There are also automotive paint forums where you could ask as well; one is Autobody 101 but there are many others.
Mike W.
Posts: 27517
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: Automotive paint hardener compatability

Post by Mike W. »

Shawn D. wrote: Jun 06, 2025 5:21 AM Why are you considering doing this? Do you already have the hardener or is it notably less expensive?
I already have two different hardeners, I'm cheap and don't want to spend any more money on the QX4 than I have to, particularly given it's current low value, the hardener is relatively expensive, and in a quart quantity, for a quart of paint which is way more than I need. Plus I already have more paint product than I need, just one more thing with a really nasty poison in it I don't really need around the house or even want to buy to recycle.
Shawn D.
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Re: Automotive paint hardener compatability

Post by Shawn D. »

Gotcha, all valid reasons!
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