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I thought the auto industry had mostly already switched to waterborne paints in the past decade or so. (Maybe the changeover is still not complete?)

csours 9y ago
I worked on a changeover in about 2013. I can't speak to much besides that. I've been let to believe there are still some plants running solvent, but those might not be in the US.
dazc 9y ago
Waterborne paints can still contain high levels of VOCs
- csours 9y ago
  High compared to water, but not compared to solvent based paint.
  - DannyBee 9y ago
    Err, 100% false. If you helped with the changeover, you should know this. VOC is not the same as HAPS. (Nor is VOC in any way related to how harmful the compounds are to people) Trivial example: Acetone is VOC exempt in the US. It's pretty trivial to make a 0 VOC solvent based coating using acetone. They tend not to because it's not horribly friendly to use, due to, among other things, how quickly acetone flashes off. In truth, water based or solvent based doesn't really change the VOC level that much these days, nor would it really matter to people. A lot of the auto paints are 2k urethanes. a 2k water based polyurethane is still gonna be isocyanate + something else. It doesn't really matter whether it's 0 VOC or not. You are going to use a supplied air respirator (minimum) because breathing isocyanate is a really bad idea. So the idea, often floated, that lowering the VOC helped people's occupational exposure, is usually unsupported by evidence, at least in the auto industry (i'm only familiar with wood and auto :P). The auto industry did not used to spray water based 2k urethanes. Now they do. Spraying and breathing a post-cat lacquer with n-butyl acetate in it + some acid, is infinitely better for you than spraying + breathing a water based 2k urethane with isocyanate in it. Are there cases it ended up better for people? Sure, of course. But most of that is completely and totally independent of VOC content. Because of course, most coatings manufacturers, surprise, optimized for legal VOC content, often at a cost to harmfulness to humans. Note that, of my professional wood coatings, my water based and solvent based still have exactly the same amount of VOC (2.75lbs). Are there some that don't? Sure. They are mostly crap, because nobody has come up with magic ways to dissolve or emulsify various polymers and catalysts :) So i can't get a water based post-cat conversion varnish that is anywhere near as good as a solvent based one. The chemistry to do it simply doesn't exist. I can get a water based 2k urethane that has as nice (or nicer) properties than that conversion varnish, but at a high possible cost to my health. I'll pass.
    - csours 9y ago
      I was involved on the IT side, not the materials side. I was probably thinking of hydrocarbons, not VOC. Also as far as I know, the clear coat is still solvent based, but I may be mistaken about that. Thanks for the detailed comment.
      - wonderbread23 9y ago
        > I was involved on the IT side Seems to be a common occurrence among in IT/ software development that being good in this field makes you an expert in others we've never worked in. I wonder why that is.

csours 9y ago

I worked on a changeover in about 2013. I can't speak to much besides that. I've been let to believe there are still some plants running solvent, but those might not be in the US.

dazc 9y ago

Waterborne paints can still contain high levels of VOCs

csours 9y ago
High compared to water, but not compared to solvent based paint.
- DannyBee 9y ago
  Err, 100% false. If you helped with the changeover, you should know this. VOC is not the same as HAPS. (Nor is VOC in any way related to how harmful the compounds are to people) Trivial example: Acetone is VOC exempt in the US. It's pretty trivial to make a 0 VOC solvent based coating using acetone. They tend not to because it's not horribly friendly to use, due to, among other things, how quickly acetone flashes off. In truth, water based or solvent based doesn't really change the VOC level that much these days, nor would it really matter to people. A lot of the auto paints are 2k urethanes. a 2k water based polyurethane is still gonna be isocyanate + something else. It doesn't really matter whether it's 0 VOC or not. You are going to use a supplied air respirator (minimum) because breathing isocyanate is a really bad idea. So the idea, often floated, that lowering the VOC helped people's occupational exposure, is usually unsupported by evidence, at least in the auto industry (i'm only familiar with wood and auto :P). The auto industry did not used to spray water based 2k urethanes. Now they do. Spraying and breathing a post-cat lacquer with n-butyl acetate in it + some acid, is infinitely better for you than spraying + breathing a water based 2k urethane with isocyanate in it. Are there cases it ended up better for people? Sure, of course. But most of that is completely and totally independent of VOC content. Because of course, most coatings manufacturers, surprise, optimized for legal VOC content, often at a cost to harmfulness to humans. Note that, of my professional wood coatings, my water based and solvent based still have exactly the same amount of VOC (2.75lbs). Are there some that don't? Sure. They are mostly crap, because nobody has come up with magic ways to dissolve or emulsify various polymers and catalysts :) So i can't get a water based post-cat conversion varnish that is anywhere near as good as a solvent based one. The chemistry to do it simply doesn't exist. I can get a water based 2k urethane that has as nice (or nicer) properties than that conversion varnish, but at a high possible cost to my health. I'll pass.
  - csours 9y ago
    I was involved on the IT side, not the materials side. I was probably thinking of hydrocarbons, not VOC. Also as far as I know, the clear coat is still solvent based, but I may be mistaken about that. Thanks for the detailed comment.
    - wonderbread23 9y ago
      > I was involved on the IT side Seems to be a common occurrence among in IT/ software development that being good in this field makes you an expert in others we've never worked in. I wonder why that is.