polyurethane not drying! - DIY (Do It Yourself)

A conversation from: http://www.hotrodders.com/forum/enamel-vs-urethane-vs-polyurethane-.html

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Barry, you responded to a post of mine on orange peel with the comment...

"Martin,

You are right to question the mils.

This is a major factor with acrylic urethanes BUT NOT a factor with Polyurethanes.

Now don't confuse what I said with "cross-linked poly's=(enamel with a polyurethane hardener) Not same ball game."

Ok, what in the heck is the difference? I understand the "poly" means "Many". My understanding is that simply means "Many" urethane resins are used. How does this make a difference in how it is "cross linked". I thought any product with a hardener is going to "cross link", even epoxy will "Cross link", creating a new compound. That is what I thought at least.

Acrylic urethane, Polyurethane, "just" Urethane. These names seem to be put on just about anything and it seems it is the marketing of the product more than the chemical make up that dictates it. They seem to be interchangable sometimes. Well, not the "Polyurethane". But for instance, S-W has a high end SS product for fleets it is called an "Acrylic Urethane". This EXACT same product is sold with a different label on the can in a "value line" and is labeled simply "Urethane". The "Polyurethanes" are mixed off the same mixing bank as the base coats (which are simply acrylic enamel) with only a change in drier (if used) and "mixing clear" or "binder" and they are magically transformed into a "polyurethane". This includes the PPG "Concept" we were talking about.

PLEASE clear this up for all of us, what makes the difference between a Polyurethane and an Acrylic Urethane? And why does it cure different?

I know there is a difference but I sware, the names are thrown around by marketing and make no sense.

The terms are misused on a regular bases.

Unfortunately there are no Urethane police.

Your ex-company is one of the very worst for playing games with the name.

In short a true polyurethane resin will have good flexibility and NEVER need a flex agent.

In short if you look at Acrylic urethane under a microscope you see the resin structure looks like a ladder (in short terms)

A polyurethane will look like an over reinforced (many times) house Gable.

Activation of Polyurethane will be 3:1, 2:1 or 1:1 as it takes more isocyanate's to lock the product down where an acrylic urethane can be activated all day long with a 4:1 mix.

Polyurethanes usually end up with a 2 pencil hardness witch is softer than an acrylic urethane, so this gives it much more stone chip resistance and a lot better adhesion.

Polyurethanes will be much more resistance to harsh chemicals and that is why on jets its a requirement.

Up until 8-9 years ago Polyurethanes were very hard to buff and to lay with out orange peel was almost impossible except where you ran it.

Link to Yourun Synthetic Material

This has all changed as there is no longer a spraying difference

between the resin systems, if the company is using newer resins.

A well made Polyurethane will also have more clarity(cleaner gloss) than an acrylic and most true with excess coats such as

custom painting.

Another benefit is is easier to make a polyurethane to buff good even 30-60 days later where a lot of clears after 3-5 days forget it on the buffing. Not all polyurethanes are easy to buff 30 days after painting but it can be done if the company wants to put the effort into it. This is very important for restoration as were painting the car in pieces off the frame and it may be 60 days before the car is put together and can be wet-sanded and buffed.

Ok, you have cleared up a lot on the linking, if I am understanding what you are saying that is. Tell me if I am wrong.

A polyurethane has "many" resins, thus many different molecules to link, right? I see a urethane as let's say black and white marbles covering the floor with strings going from one to another. Then polyurethane as black, white, red and blue marbles covering the floor with strings going from every white one to every other color and every red one to every other color and so on. Am I on the right track?

Ok, if I am on the right track that is great. But now with the confusion. You say that a urethane would have a 4:1 mixing ratio with hardener and a polyurethane would have a 2:1, 3:1 or 1:1 ratio, or do you mean the ratio with iso molecules?

Because if you mean with hardener, S-W acrylic urethanes use a 3:1 ratio. And by the way, you mentioned PPG "Concept" SS in that other thread implying it was a polyurethane. But it is advertised as a acyrlic urethane, not a poly.

If you are talking about the mixing ratio with hardener, how do you know how much Isos are in said hardener by wieght or volume or what ever? Couldn't a pint of hardener from one brand or product line have a different amount of isos than another pint from another line or brand?

Ok, next question, I mentioned this in the first post. Many of these products like IMRON and S-W Genisis and PPG Delta have dedicated mixing banks. The toners and hardeners are not used with any other system. This makes sense, as far as the name it is called actually being believable. Genisis is called a "true" acrylic urethane while IMRON as I remember is a polyurethane and Delta, I don't remember, I think it is just refered to as a "urethane". Anyway, ok, they have a dedicated system.

What about something like Chromaone, Concept, or TecONE they are mixed off a mixing bank which also provides the base coats, interior colors, (with S-W a number of different urethane SS) and even acrylic enamel on some of them. All these systems use ALL the same toners for all the "qualities". All of these systems are basically, acrylic enamel systems! Yet with a different mixing clear or "drier" or something they magically become an "Acrylic urethane"?

**** End of quoted thread ****

In short, did you use polyurathane, polyurethane, or an acrylic polyurathene? If it does not dry, remove it with acetone, sand down to wood and change brands. Minwax clear gloss fast drying polyurethane, sku is s good choice for the rattle can user. There are also cans of brush on of the same goop that with a thinning agent can be sprayed with an airgun.

EPODEX &#; Polyurethane Hardener (without Resin)

The hardener B-component must be mixed with the resin A-component before use.

Coating and Sealing with PU Resin

1. Coat the surface with the PU resin.
2. To do this, mix the PU resin (A) with the appropriate PU hardener (B) in the specified mixing ratio. PU glossy: 10:2 by weight (e.g.: 1kg A + 0.2kg B); PU matt: 10:1 by weight (e.g.: 1kg A + 0.1kg B). Optionally, you can add up to 20% water.
3. Transfer the mixture to a paint tray and mix again. This way you make sure that resin (A) and hardener (B) mix completely.
4. If a transparent coating is not desired, mix the supplied WB colour paste with the resin-hardener mixture to colour the transparent mixture. We recommend a colour proportion of approx. 10%, e.g., 100g WB colour paste to 1.1kg or 1.2kg resin+hardener. We recommend mixing smaller quantities of approx.1kg per coat, as the material, is very productive and sets quickly (pot life: 60 min. with 1kg).
5. Apply the material thinly with a foam roller in a criss-cross pattern. To achieve an even finish, use our scraper grid to scrape off excess material before application. We recommend a layer thickness of max.150µm.
6. The material can be walked on after approx. 20-24 hours and is completely chemically cured after approx.7 days.

Pro Tip: We recommend adding water to the PU resin when working at high ambient temperatures or when mixing a large quantity in order to avoid an orange peel texture.

Customer Service: If you have further questions, please contact us by , or use our support.

Note: Please note that due to different lighting conditions and monitors, the colours may not be uniformly displayed.

Ingredients, Security & Danger statements

B-Components (PU Matt) Warning: Hexamethylene diisocyanate oligomers Benzene, 1,3-diisocyanatomethyl-, polymer with 1,6-diisocyanatohexane, polyethyl hexamethylene-di-isocyanate: May produce an allergic reaction. Harmful if inhaled. Causes serious eye irritation May cause an allergic skin reaction May cause respiratory irritation. Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves/eye protection/face protection. Call a POISON CENTER/doctor if you feel unwell. If skin irritation or rash occurs: Get medical advice/attention. If eye irritation persists: Get medical advice/attention. Take off contaminated clothing and wash it before reuse. Contains isocyanates. May produce an allergic reaction.

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