What is the difference between urethane and polyurethane? My wife's uncle paints for a living and I have looked at a couple of his custom jobs and they look good. He said he mixes urethane single stage and urethane clear 50/50 and sprays. They have good depth and shine and I wonder if he is giving me good advise or blowing smoke up my butt. Thanks, David
07-05-2005 08:01 PM
BarryK can give you the N'th degree explanation but simply put, Poly means "Many" so polyurethan's have more solids. Such as Polyurethane build primers like FeatherFill 2 by Evercoat. Like sprayable plastic filler.
Clear over/mixed with a single stage paint is as old as clear coat. It gives a nicer finish and more depth as the clear is a magnifier.
The downside is,Those jobs are a royal pain to repair.
07-05-2005 09:04 PM
Adding a compatable clear to a singlestage solid color adds depth and makes it easier to buff IMO, you wouldn't want to do this with a metalic color though. I've done a few black singlestage jobs with 50/50 clear mix on the last two coats and they did look nice and deep, most lighter colors will look brighter, dark colors look darker.
07-05-2005 09:44 PM
I don't know what the exact chemical differences are, not a chemist, but polyurethanes are slightly tougher then urethanes. Polyurethanes cure so hard that if they aren't buffed within a number of days, it will be very hard to buff out the wetsanding scratches. A popular polyurethane paint was imron by dupont, and is often used on fleet equiptment that may see rough use. Pierce mfg here in Wisconsin use to use imron on there fire trucks back 15 years ago when I went on a tour of their plant in tech school. I am not sure if they are still using imron or not. Many people will add clear to the last coat or two of single stage, but I haven't personally done it. Almost everything I spray is basecoat with a urethane clear, but will spray single stage acrylic enamel with hardener if I am painting something to do on the cheap. Both urethanes and polyurethanes single stage paints are available, and also available as clearcoat to spray over a base color.
07-05-2005 10:34 PM
Need advice on a paint job
Hello I am a trouble lady trying to understand paint jobs.....I have a 95 Camry in need of a good paint job....I have two guys that have agreed to paint my car both have agreed to paint the car for the the same price ($500)...I am interested in a good paint job that will possible last another 3-5 years....nothing spectacular but a quality job and I want a high gloss shine and both of them come highly recommened by other clients....My dilemna is the type of paint they use...one claims to use a polyurethane paint and says that it will shine and that I will not need a clear coat on top, he claims that it will peel in the end anyway......While the other claims to use Omni 2000 paint with a clear coat on top of and he guarantees to match the paint...He says he will use a clear coat to make it shine......My question is what is the best kind of paint to ask this person to purchase for a quality paint job for the money.....He states he would probably like to spend about $150-$200 on yhr paint and $300 on the labor.....What type of paint would be suffiecient for what I would want.....I want the car to shine the best it can and also how many coats of clear should I ask him to paint on top? What is the best paint for my money if I am paying him $500?
07-05-2005 11:15 PM
Hey tish, you may want to start a new topic instead of jumping in on this one and you will get better replys. I don't know what prices are like where you are, but the prices you quoted to spend on materials won't get you far around here. I would stay away from the guy telling you the paint will peel in a few years anyways. Good paint does not peel, and if it does it is usually do to the prep and sanding, or not using the product properly. So far I would say go with the base clear paint job. Anything else I will wait till a new post. But even one of the cheapest automotive paints, acrylic enamel without a clearcoat on top should be able to last 3-5 years with good gloss, but a hardener should be used.
07-05-2005 11:53 PM
i agree. i dont know what the prices are around your area but i cant see you getting much of a quality job for $500. i dont know of any bodyshop around here that will paint a whole car for under $2000. if you are forced to go with one of the 2 then use the guy that will put omni on the car. just by what the other guy told you tells me he knows nothing and is out to decieve you. as a customer you should not have to tell the painter how many coats of clear to put on. he is the professional and should know how to do his job properly. most manufacturers recommend 2-3 coats. i really dont think 150-200 will cover the materials on a basecoat/clearcoat job. it will be enough for the guy using the polyurethane because its generally cheaper and doesn't use a clearcoat. your car was originally painted with basecoat/clearcoat.
07-06-2005 05:35 AM
Hey you all, i have seen factory clear coats peel on new cars. This is what you pay high dollors for on a new car. I still like a clear coat on my cars, but beware of what you pay for.
07-06-2005 06:08 AM
the factory can have paint problems juat like anyone else. if the clear peels on a new car than something is wrong. it doesn't mean there are inherent problems with bc/cc systems. urethanes, polyurethanes and acrylic enamel can do the same thing if not prepped right. if done right bc/cc will last the same if not longer than the other systems.
07-06-2005 07:25 AM
Yeah most likely due to the manufacturer of the vehicle trying to cut costs, but ends up costing them much more in the end. Repainted quite a few in the early 90's. ford, gm, and chrysler all had peelers then. Also most factory cars have a lot of orange peel in thier paint jobs too, and that is not the fault of the paint either.
07-06-2005 06:08 PM
Originally Posted by Bee4Me
Such as Polyurethane build primers like FeatherFill 2 by Evercoat. Like sprayable plastic filler.
High build primers like FeatherFill and plastic filler are polyester not polyurethane.
07-06-2005 08:14 PM
Thanks for the clarification roger. My fault,thinking one and typing another. :rolleyes: Multitasking is not my thing. Heck,singletasking is tough enough. Poly this and poly that,
Polly want a cracker?
07-06-2005 09:23 PM
Just for the record, in the context of 2 component automotive finishes, the two terms urethane and polyurethane are synonomous and can be used interchangeably.
For those interested in learning more: A urethane linkage (-NHCO0-) is the reaction product between a hydroxyl group (-OH) and an isocyanate group (-NCO). The prefix poly- simply means that the product is a polymer containing the said linkages.
In most automotive topcoats nowadays, the hydroxyl component is an acrylic resin with pendant hydroxyl groups, and the isocyanate is a biuret or trimer of hexamethylene diisocyanate. However, other types of urethane finishes also exist in primarily non-automotive applications, such as polyester-urethanes, vinyl-urethanes, or alkyd-urethanes. One also can encounter the so-called oil-modified urethane varnishes in architectural applications, which are single component products which cure by oxidation (with the urethane linkage being present in the backbone of the polymer). Finally, there are moisture-cured products, which are multifunctional isocyanates that react with atmospheric moisture to crosslink and cure (eg POR-15).
I hope people don't find this boring or rambling.
07-06-2005 09:34 PM
Not boring at all, tell us more. I've done some ingredient comparisons from can to can and see a lot of component similarities, there are some ingredients in the higher end clears that start with the poly prefix which I always thought interesting. Are there any key ingredients to look for which would identify a quality product? Interesting stuff. Bob
07-06-2005 10:18 PM
woah, don't think I understand most of that, but interesting. The ingrediant that catches my attention is the hardener with most of the ingredients being some kind of isocyanate in the name. Bad stuff menard. Now stuff like resin and mek and acetate I can understand, but all the complex chemical names I don't but they are probably a combination of chemicals. It was always my understanding that the most durable were polyurethanes, but don't know now that I read what powderbill wrote. But the clears labeled polyurethane say to buff within a certain time period in some tech sheets. The urethane clears I haven't seen say this. Seen powder bills occupation was a chemist. Who woulda thunk it. :thumbup:
I often see a lot of similar chemicals in the hardeners for urethane primers as the clear. One time I had a small part I had to clear and was out of hardener for the clear. Used some primer hardener so I didn't have to go spring for the hardener for the clear. I mixed a little up and let it sit overnight and the next day it was hardened up, so I used the primer hardener. Didn't see if there were any long term effects though.