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Thread: urethane and polyurethane base

  1. #1
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    Default urethane and polyurethane base

    What is the difference in urethane paint and polyurethane paint? What is each best suited for?

  2. #2
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    This what I came up with and what I was told by a couple different people in the paint manufacturing business.


    "Polyurethane and urethane are terms which are used interchangeably. The term polyurethane came about in the past because the predominant chemical group present in the polymer was the urethane group. Today the term polyurethane may be somewhat misleading because it covers a wide variety of materials which may have similar general characteristics, but can differ in specific properties. These properties are explained by different chemical structures existing in polyurethanes." (end quote).


    Imron (Dupont - polyurethane paint) has for the last close to 40 years been used on over the road semi-trucks, air planes etc. Mainly commercial uses because of it durability (that is and was some tough paint). But in all honesty its about the same as the current urethane paints we put on cars today.

  3. #3
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    Maybe your thinking of polyester paint vs urethane ???

  4. #4
    dusty-ole-spraygun Guest

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    Quote Originally Posted by tommyb
    What is the difference in urethane paint and polyurethane paint? What is each best suited for?

    I also was puzzled by these terms myself, and did some research, this is what I found.

    It's not really a question of polyurethane vs. urethane, those 2 terms mean the same thing. Urethane is one molecule of the paint, polyurethane is many molecules of the paint linked together. Those 2 terms basically mean the same thing, like comparing the words "gas" and "gasoline"- same stuff. If you took one molecule of Imron polyurethane paint, you'd have a urethane molecule. Urethane is the singular term for polyurethane, and vice versa- "Poly" means "many", or more than one, so polyurethane is the plural term for urethane.

    The subject really is, polyurethane vs. acrylic urethane. A true polyurethane and an acrylic urethane are 2 different paint systems. The acrylic urethane is not as pliable and will crack easier, the polyurethane won't crack as easily. The acrylic urethane will not have as strong UV protection as the polyurethane- and UV protectors are often added to acrylic urethane.

    Painters maintain- and I've seen this with my own eyes- the acrylic urethane is easier to spray, and will give a higher/deeper degree of gloss- it's also easier to wet sand/buff, and is the standard now for restorations, street machines, hot rods, and many commuter repaints, etc.

    People that want to go that extra degree of durability and want the utmost bulletproof paint job or restoration, use Imron, which is a true polyurethane.

    Here's an example of someone using Imron Polyurethane to restore a Stanley steamer car, he had a choice of the 2 paints you ask about in your post, this clears it up to a great degree. It's not urethane vs. polyurethane, those 2 terms mean the same thing- the issue is really acrylic urethane vs. polyurethane- this also keys in on the high solids/HVLP topic as a sidepoint

    http://stanleymotorcarriage.com/735r...aintSystem.htm

    "Urethane based paints are called high solid compounds and urethanes will last longer and are tougher providing a high gloss finish. Urethane is also the most expensive of the three paint systems. For urethane systems a proper preparation of the body metal and proper body fillers and materials must be used. Urethane systems have a chemical nature whereby the molecules in the paint form cross-linked chains. If the surface preparation is not properly done urethane systems will literally pull the substrate apart and the urethane paint will peel from the surface it has been applied to.

    There are two urethane “systems” of paints ~ acrylic urethane and polyurethane. Acrylic urethane systems are somewhat easier to apply but have the disadvantage that they are not as flexible once applied to the finished surface. Paint a sheet of aluminum foil with both acrylic urethane and polyurethane, allow it to properly cure, then wrinkle the aluminum and fold it back out and, except for the crease marks, the polyurethane painted portion will look far superior to the acrylic painted portion. Additionally polyurethane paint systems have a high degree of resistance to the damaging effects of the ultraviolet rays from the sun. When applying acrylic urethanes a high level of ultraviolet inhibitor needs to be added to achieve the natural ultraviolet resistance of polyurethane automotive paints. With a slight amount of ultraviolet inhibitor added polyurethane paints can be made nearly immune to ultraviolet ray damage. With respect to the sun, elements, and general toughness of the paint, acrylic urethanes are not as durable over time as are polyurethane systems. Polyurethane paints have the highest degree of chip, nick, and scratch resistance of all automotive paint systems when properly applied.

    Considering all the conditions present including steam, steam cylinder oil, high temperature, and exposure to the sun, rain, and elements on occasion, DuPont’s Imron polyurethane enamel paint system was chosen over Valspar’s arcylic urethane paint system. The colors selected would be Black RS-99, Dark Red RS-910, and Light Red RS-593. Since Environmental Protection Agency (EPA) rulings have led to a reduction of Volatile Organic Compounds (VOCs) in paint, the paint system chosen would need to comply with EPA guidelines. Additionally the high-volume/low-pressure (HVLP) spray guns to apply these environmentally friendly coatings would also be used."



    now the shocking part- this guy is painting Imron in a spray booth, there is overspray blowing around, but he only has a half-mask on with no air supply, and his bare head is showing uncovered while mixing the paint- IMHO not too smart while using Imron. Imron is the most dangerous paint of any to spray, what he's doing is risky. The paint/catalyst will absorb into the human body through skin and eyes, and once it's in your body, it doesn't leave- it builds up in your blood, bones, liver, lungs, etc. He's mixing Imron and catalyst with his bare hands, and he has paint on his hands from the 2-part primer/sealer he used- but he does have gloves on while spraying it. Just getting a little catalyzed synthetic enamel paint on my hands one time, made the bones in my fingers feel cold and numb for a few hours. He should be using gloves and eye protection throughout- like a full face mask- or at least have his head covered with the hood, with safety goggles on to protect against splash/overspray.

    http://stanleymotorcarriage.com/735r...ntingBody2.htm

    http://stanleymotorcarriage.com/735r...ntingBody1.htm
    Last edited by dusty-ole-spraygun; 10-04-2008 at 08:10 AM.

  5. #5

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    [QUOTE=dusty-ole-spraygun]I also was puzzled by these terms and did some research, this is what I found.

    It's not really a question of polyurethane vs. urethane, those 2 terms mean the same thing. Urethane is one molecule of the paint, polyurethane is many molecules of the paint linked together. Those 2 terms basically mean the same thing, like comparing the words "gas" and "gasoline"- same stuff.

    The subject really is, polyurethane vs. acrylic urethane. A true polyurethane and an acrylic urethane are different. The acrylic urethane is not as pliable and will crack easier, the polyurethane won't crack as easily. The acrylic urethane will not have as strong UV protection as the polyurethane.

    Painters maintain, and I've seen this with my own eyes, the acrylic urethane is easier to spray, and will give a slightly higher degree of gloss, and is the standard now for restorations, street machines, hot rods, and commuter repaints, etc.

    People that want to go that extra degree of durability and want the utmost bulletproof paint job restoration, use Imron, which is a true polyurethane.

    Here's an example of what one guy did restoring a Stanley steamer car, he had a choice of the 2 paints you ask about in your post, this clears it up to a great degree. It's not urethane vs. polyurethane, those 2 terms mean the same thing- the issue is really acrylic urethane vs. polyurethane- this also keys in on the high solids/HVLP topic as a sidepoint

    http://stanleymotorcarriage.com/735r...aintSystem.htm

    "Urethane based paints are called high solid compounds and urethanes will last longer and are tougher providing a high gloss finish. Urethane is also the most expensive of the three paint systems. For urethane systems a proper preparation of the body metal and proper body fillers and materials must be used. Urethane systems have a chemical nature whereby the molecules in the paint form cross-linked chains. If the surface preparation is not properly done urethane systems will literally pull the substrate apart and the urethane paint will peel from the surface it has been applied to.

    There are two urethane “systems” of paints ~ acrylic urethane and polyurethane. Acrylic urethane systems are somewhat easier to apply but have the disadvantage that they are not as flexible once applied to the finished surface. Paint a sheet of aluminum foil with both acrylic urethane and polyurethane, allow it to properly cure, then wrinkle the aluminum and fold it back out and, except for the crease marks, the polyurethane painted portion will look far superior to the acrylic painted portion. Additionally polyurethane paint systems have a high degree of resistance to the damaging effects of the ultraviolet rays from the sun. When applying acrylic urethanes a high level of ultraviolet inhibitor needs to be added to achieve the natural ultraviolet resistance of polyurethane automotive paints. With a slight amount of ultraviolet inhibitor added polyurethane paints can be made nearly immune to ultraviolet ray damage. With respect to the sun, elements, and general toughness of the paint, acrylic urethanes are not as durable over time as are polyurethane systems. Polyurethane paints have the highest degree of chip, nick, and scratch resistance of all automotive paint systems when properly applied.

    Considering all the conditions present including steam, steam cylinder oil, high temperature, and exposure to the sun, rain, and elements on occasion, DuPont’s Imron polyurethane enamel paint system was chosen over Valspar’s arcylic urethane paint system. The colors selected would be Black RS-99, Dark Red RS-910, and Light Red RS-593. Since Environmental Protection Agency (EPA) rulings have led to a reduction of Volatile Organic Compounds (VOCs) in paint, the paint system chosen would need to comply with EPA guidelines. Additionally the high-volume/low-pressure (HVLP) spray guns to apply these environmentally friendly coatings would also be used."



    now the shocking part- this guy is painting Imron in a spray booth, there is overspray blowing around, but he only has a half-mask on with no air supply, and his bare head is showing uncovered- IMHO not too smart while using Imron. Imron is the most dangerous paint of any to spray, what he's doing is risky. He's mixing Imron and catalyst with his bare hands, and he has paint on his hands from the 2-part primer/sealer he used. Just getting that stuff on my hands one time, made the bones in my fingers feel cold and numb for a few hours. He should be using gloves, and at least have his head covered with the hood- and goggles on.

    ...now I'm wondering if " Acrylic Lacquer " is nothing more than " Acrylic Urethane"....by the way, I read the article you posted in "urethanes are new , not "...luv it

  6. #6

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    Here's a link that covers polys/urethanes without too much mumbo jumbo. It's focused more on the foam type poly, but they have the same chemical makeup as a paint vehicle...I'm just guessin ,but I'd say today that 'urethane' is more like the glue that holds poly groups together...sorta like all that DNA strand mumbly jumbly you hear about...tomorrow, I might have a completely different take on it. heheh

    http://www.madehow.com/Volume-6/Polyurethane.html

  7. #7
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    Actually just about all of the better car manufacturers have gone over to acrylic urethane because it looks better and holds up better than other products. It started with the high-end cars but now just about all of them are using AU. Imron was/is much more dangerous than most other types of urethane paint in that contains a lot more isos so, if painting with Imron, you've got to be extra careful not to come in contact with the paint. No breathing or skin exposure. This is also highly recommended for ANY urethane spraying.

    Imron is tough stuff and it's typical use is for painting trucks, airplanes and other surfaces that are exposed to constant UV and weather and don't need to be as glamorous as automobile paint. Imron was one of the first polyurethanes on the market for commercial body shops but fell out of favor because it didn't match factory finishes and was very dangerous to spray. While the new acrylic urethane paints are also dangerous they hold up very well, are easier to match and repair and look a lot better because of their depth, gloss and color.

    We spray Imron occasionally for projects that need that extra toughness but we shy away from it for almost all of our spraying because of the aforementioned reasons. However, in recent years, they may have reduced the amount of isos but I've heard so many horror stories about this product that we don't even consider it unless the project demands it.

  8. #8
    dusty-ole-spraygun Guest

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    Len- that's great first hand info, thanks for sharing it. I often wondered why "everyone" wasn't using Imron- I mean, if it was so "good" why didn't every single painter just go to it. Not only expense, but health issues- many shops just didn't want to spend the money for supplied air respirators, downdraft booths, etc., or valued their lives and health more, rather than how long some customer's paint job held out.

    I think I know your opinion on this already, but what do you think of the guy mixing Imron with no respirator or gloves, and spraying it with his head and eyes exposed ? Risky, or no ? Can he get away with that safely in a spray booth like that ?

    There's a good post on this subject that explains how acrylic urethane uses an acrylic binder, while true polyurethanes like Imron use a polyester binder (similar to epoxy primers or polyester spray filler)- I found the post here in the archives, it quoted a Dupont tech bulletin titled "understanding paint chemisty", here's the link and post, posted by "Andy"

    http://autobodystore.com/forum/showt...e+polyurethane

    "This is from the Dupont tech sheet "Understanding Paint Chemistry". I would think the same would apply to clear coats. As I understand it, both are similar except acrylic urethane is an acrylic binder combined with an isocyanate hardener. A true polyurethane (i.e. Imron) is a polyester binder combined with an iso hardener. Of the two, polyurethane is harder and more durable.

    Polyurethane has also become a very generic term describing a very wide range of products....some good and some inferior.

    I think most modern automotive clearcoats are acrylic urethane. If you get more specific about which clears you are considering, someone on this site could give you recomendations."

  9. #9
    dusty-ole-spraygun Guest

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    truth be told, a good number of people damaged their health, and died, from Imron and similar Urethane paints- and Dupont was sued repeatedly for it. Here's one particular sad case, where the painter just would not listen to the MD and stop using ISO paints- oddly enough the writeup states even outside the paints are not safe, and use supplied air with them- I know many painters just using an exhaust fan in a home-made spray booth bay of a garage, and standard lacquer/enamel respirator, to spray urethanes- the only positive point I can see is, it took 20 years of poor safety/painting practices and workplace abuse to kill this person, but he was only 37 years old when he died from painting urethane.

    http://www.sp2.org/newsletters/sp2vo...1iss8topic.php

    Case - Spray Painting (Resulted in Death)*

    A 37-year-old male, self-employed car painter was admitted to the hospital with asthma symptoms. These symptoms had first started five years earlier and even then were thought to be related to his occupation. Apparently shop conditions were poor and he was not trained and/or decided not to adopt safe working habits or use protective personal equipment. He had been working in the same work environment for more than 20 years.

    The man was diagnosed by a doctor with occupational asthma “induced by Isocyanates”. Medical experts advised him to change his job or avoid the use of two part or catalyzed polyurethane paints. In spite of the advice, he continued to work. He used medications such as bronchodilators, cromolyn, and steroids to self medicate and treat his condition.

    Six years later, and in spite of doctors’ recommendations, the painter was still working. While spraying a car with an isocyanate paint, he developed a more severe, prolonged asthma condition. Despite medication, he remained symptomatic, especially at night. When he returned to work and sprayed the polyurethane paint yet again, he suffered a severe asthma attack. He died in the ambulance enroute to the hospital.

  10. #10
    dusty-ole-spraygun Guest

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    [QUOTE=rigidude
    ...now I'm wondering if " Acrylic Lacquer " is nothing more than " Acrylic Urethane"....by the way, I read the article you posted in "urethanes are new , not "...luv it[/QUOTE]


    glad to hear you appreciated that thread- leave it to the Germans to invent the stuff- we won the war, and the USA seized German missiles, rocket engines, paints, jets, submarines, assault rifles, etc. as part of the spoils. Our first jets and nuclear subs were based on German hull designs from WWII. Today's cruise missiles and nuclear ICBM's, are modern versions of German V-1 and V-2 weapons. The M-16 rifle is an improved American version of the German Sturmgevehr assault rifle- the Russian AK47 is practically a direct copy of the German gun, made 2 years after the war ended. Germans had the most advanced technology, hands down- they were a decade ahead of everyone else during that era.

  11. #11
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    All spray painting is dangerous and breathing ANYTHING needs to be controlled. When spraying lacquer or any non-hardened materials you can usually get away with a decent carbon canister cartridge mask. Even spraying hardened product minimally you can use this type of protection but, because canister masks have limited life and are "negative pressure", it's highly recommended that a supplied air system be used.

    When using a cartridge mask the prefilters begin to get coated with overspray as soon as you start spraying and the longer you paint the more the filters get coated. This causes the negative pressure in the mask to drop further in order to pull in the same amount of air and the possibility of leakage (where the mask contacts the skin) to increase substantially. The good think about positive pressure is that a leak will leak OUT and not in.

    Most canister masks need to have the canister changed after 6 to 10 hours of exposure but most supplied air systems can go for extremely long periods without the need for service. The Hobbyair system below only needs a heppa inlet filter that is changed when it gets dirty but if it's used properly the inlet filter lasts a long time.

  12. #12
    dusty-ole-spraygun Guest

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    that is a good deal on a supplied air mask, thanks for sharing it

  13. #13
    dusty-ole-spraygun Guest

    Default check the MSDS sheets

    Quote Originally Posted by jimmo4life
    Maybe your thinking of polyester paint vs urethane ???

    The lines between polyester and acrylic urethane/polyurethane have become somewhat blurred lately.

    In the case of Dupont Imron Polyurethane, if you read the MSDS sheets on the ingredients, it has both polyester and acrylic polymers in it- hence it's a "blend" of the 2 technologies. It's like mixing acrylic enamel with epoxy paint.

    Even Centari acrylic enamel, has one polyester in it, with many acrylic polymers

    As Dupont goes up the durability scale with their paints, they added more and more polyesters to the paint, first one, then 2, and the most durable paints from Dupont have 3 polyester ingredients- there are more than one type of Imron now, there's at least 3 different grades of Imron- yet all of them have many acrylic polymers in them as well

    the polyester is what makes an industrial paint really hard and tough- think of JB Weld epoxy after it dries for a few days, it's like a rock-the polyester is what makes a paint really deadly to spray too- if breathed in, it hardens in your lungs just like JB Weld- the acrylic polymers are "slightly" softer and give a deeper gloss, and are also dangerous to spray- Dupont has obviously blended the technologies- a combination of polyester and acrylic polymer obviously has the hazards of both combined, but also the good qualities of both- hard finish, but somewhat pliable too so it can be sanded/buffed easier

    if you go to the Dupont site and check the MSDS sheets, the ingredients are listed- one nice thing about the old Dulux, and other true synthetic enamels like Valspar, etc.- synthetic enamel has no polyesters or acrylic polymers in them, and are a lot safer to spray

    a true 100% polyester paint would be very difficult to wetsand and buff, and would even resist sandblasting, paint remover, and thinners to a high degree- I've run into a few epoxy primers on cars, that would not come off easily and were very stubborn to remove, even with a huge sandblasting rig

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